iLfili iilii iiiii: iiiv BOUGHT WITH THE INCOME FROM THE SAGE ENDOWMENT FUND THE GIFT OF Henrg M. Sage ENyiNEfRiNG Library Cornell University Librarv TN 22.K32 1903 The ore deposits of the United States an 3 1924 004 088 690 The date shciVs when this volume was [taken. ^>fc All books not in use for instniction or re- search are limited to all borrowers. fRiHTlP* 111' Volumes of periodi- 'iifL' "^ -^ cals and of pamphlets comprise so many sub- 10 TJl"^ '1 ^^ jects.that they are held •'' " in the library as much as possible. For spe- (r»o ij|( .„^ , cial p\irpo.ses they are '' ' "'■^'. ..T^ fjiven out for a limited time. Graduates and sen- iors are allowed five volumes for twoweeks. Other students may have two vols, from the circulating library for two weeks. Books not needed during recess periods should be returned to the library , or arrange- ments made for their return during borrow- •er's absence, il wanted. Books needed by more than one person are held on the reserve li.st. Books of special value and gift books, when the giver wishes it, are not allowed to circulate. . 77/ 2Z /9^3 .% Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924004088690 THE ORE DEPOSITS OF THE UNITED STATES AND CANADA. BY JAMES FURMAN KEMP, A.B., E.M., PROFESSOR OF GEOLOGY IN THE SCHOOL OF MINES, COLUMBIA UNIVERSITY. FIFTH EDITION. ENTIRELY REWRITTEN AND ENLARGED. THE ENGINEERING AND MINING JOURNAL, 261 BROADWAY, NEW YORK. LONDON, 30 BUCKLERSBURY. 1903. T h~m^c% COPTRIGHT, 1893 AUD 1900 BY THE SCIENTIFIC PUBLISHING COMPANY. Copyright, 1903, BY THE ENGINEERING AND MINING JOURNAL. dJJ PEEFACE. The following pages presuppose for their apprehension some acquaintance with geologj' and mineralogy. The mate- rials for them bave been collected and arranged in connection with lectures on economic geology, first at Cornell University and later at the School of Mines, Columbia College. To the descriptions of others the author has endeavored to add, as far as possible, observations made by himself in travel during the last ten years. The purpose of the book is twofold, and this fact has been conscientiously kept in view. It is, on the one hand, intended to supply a condensed account of the metallifer- ous resources of the country, which will be readable and serv- iceable as a text-book and work of reference. For this rea- son every effort has been put forth to make the bibliography complete, so that, in cases where fuller accounts of a region are desired, the original sources may be made available in any good library. But, on the other hand, it has also been the hope and ambition of the author to treat the subject in such a way as to stimulate investigation and study of these interesting phenomena. If, by giving an extended view over the field, and by making clear what our best workers have done in late years toward explaining the puzzling yet vastly important questions of origin and formation, some encouragement may be afforded those in a position to observe and ponder, the second aim will be fulfilled. In carrying out this purpose, the best work of Tecent investigators on the origin and changes of rocks, espe- cially as brought out by microscopic study, has been kept con- stantly in mind, and likewise in the artificial production of the ore and gangue minerals. So much unsound and foolish theo- rizing has been uttered and believed about ores, that too much care cannot be exercised in basing explanations on reasonable and right foundations. vi PREFACE. Acknowledgments are due to many friends for encourage- ment, suggestion, and criticism. To Prof. Henry S. Williams, now of Yale, but late of Cornell, whose interest made the book possible, these are especially to he made. On particular regiocs much advice has been obtained from Dr. W. P. Jenney, for which the author is grateful. In the same way Prof. H. A. Wheeler, of St. Louis, Prof. E. A. F. Penrose, of Chicago, and several other friends have contributed. Dr. R. W. Raymond suggested the method of enumerating the paragraphs. It has the advantages of being elastic and of showing at once in what part of the book any paragraph is situated. The geologists of the United States Geological Survey, who have been engaged in the study of our great mining regions, especially in the West, have laid the whole scientific world un- der a debt of gratitude, and in this country have probably been the most potent influences toward right geological conceptions regarding ores. Of authors abroad, Von Groddack has been a means of inspiration to all readers of German who have inter- ested themselves in this branch of geology. The writer cannot well forbear acknowledging their influence. Should errors be noted by any reader, the writer will be very appreciative of the kindness if his attention is called to them. J. F. Kemp. CoLUMBiAij College, in the City op New York, 1893. PREFACE TO THE SECOND EDITION. In the second edition many pages have been rewritten and ex- panded. The endeavor has been also made to introduce into the body of the work the new materials that have become avail- able in the last year. This is especially true of iron ores, of the geology of the Sierras, and of nickel and cobalt. In all some fifty pages of new matter have been added, and fifteen cuts. Acknowledgments are herewith made to Professors W. H. Pettee, of Ann Arbor; H. S. Mimroe, of New York; and C. H. Smyth, Jr., of Hamilton College; and to Mr. now Prof. H. L. Smyth, of Cambridge, and Prof. W. C, Knight, of Laramie, for suggestions, as requested in the preface to the first edition. 1895. J. F, K. PREFACE TO THE THIRD EDITION. In the third edition the title has been expanded so as to in- clude Canada, since the nature of the contents now justifies this change. About one hundred pages of new matter have been added, and considerable portions of the former text have been rewritten. The figures have been doubled in number, and many maps have been introduced. The writer's thanks are due for advice and assistance to Messrs. W. H. Weed, H. W, Turner and John D. Irving, of the United States Geological Survey, to Mr. H. F. Bain, of the Iowa Geological Survey, to Mr. S. S. Fowler, of Nelson, B, C, and to many of his students, now in the active practice of the profession of mining engi- neering. J. F. K. December, 1899. TABLE OF CONTENTS. Peefaoe V List of Illustrations xv List of Abbreviations xsi PART I.— INTRODUCTORY. CHAPTER I. — General Geological Facts and Principles. The two standpoints of geology, 3, 4 ; the scheme of classifica^ tion, 4, 5; classification of rocks, 6; brief topographical survey of the United States, 7, 8; brief geological outline, 8-11; forms as- sumed by rock masses, 11, 13 1-12 CHj?iPTER II.— The Formation op Cavities in Rocks. Tension joints, 13, 14; cleavage, fissility, and compression joints, 14r-lQ; by more extensive movements, 16-31; faults, 31-35; zones of possible fracture in the earth's crust, 3.5, 36 ; secondary modifications of cavities, 36-33 13-32 CHAPTER III. — The Minerals Important as Ores; the Gangite Minerals, and the Sources whence both are Derived. The minerals, 33; source of the metals, 33-38 .33^38 CHAPTER IV. — On the Filling of Mineral Veins. Resume, 39 ; methods of filling, 39, 40 ; lateral secretion, 40 ; ascension by infiltration, 40-44 ; replacement, 44-46 39-46 CHAPTER V. — On Certain Structural Features of Mineral Veins. Banded structure, 47-49; clay selvage, 49; pinches, swells, lateral enrichments, 49, 50 ; changes in character of vein filling, 50 ; secondary alteration of the minerals in veins, 50-53 : electrical activity, 53, 53 47-53 CHAPTER VI. — The Classification of Ore Deposits, a Review and a Scheme Based on Origin. Statement of principles, 54, 55 ; principal schemes, 55 ; scheme entirely based on origin, 55-59 ; remarks on the above, and dis- cussion of methods of formation, 59-73; fahlbands, 73; phrase- ology used, 73 ; character of the rocks containing the deposits, 73 ; general bibliography of ore deposits, 74-79 54-79 X TABLE OF CONTENTS. PART 11.— THE ORE DEPOSITS. PAGE CHAPTER I.— The Iron Series (in Part).— Intboduotory Remarks ON Iron Ores. — Limonite. — Sidehite. General literature, 83, 84; table of analyses, 84; general re- marks on composition and occurrence, 85-87 ; Limonite, Example 1, bog-ore, 87-92; Examples, brown hematite not Siluro-Cambrian, 92-100; Example 2a, Siluro-Cambrian brown hematites, 100-104; origin of same, 104, 105; analyses of Umonites, 106; siderite or spathic ore, introductory, 106; Example 3, clay ironstone, 106, 107; Example 3a, black-band, 107-110; Example 4, Burden Mines, 110, 111; Example 5, Roxbury, Conn., 112; genetic discussion of siderite, 112, 113 83-113 CHAPTER II.— The Iron Series, Continued— Hematites, Red and Specular. Introductory remarks, 114; Example 6, Clinton ore, 114-131; Greenbrier Co., W. Va., 121; Mansfield ores, Penn., 121, 152; Ex- ample 7, Crawford Co., Mo., 122, 123; Example 8, Jefferson Co., N. Y., 123-125; Example 9, Lake Superior hematites, 125; intro- ductory, 125-129; Marquette district, 129-136; Menominee dis- trict, 136-139; Penokee-Gogebic district, 139-143; Vermilion Lake and range, 144-150; Mesabi, 150-154; Example 10, James River, Va., 154, 155; Example 11, Pilot Knob, Mo., 155-157; Example 11a, Iron Mountain, Mo., 157, 158; analyses of hematites, 159.. 114-159 Chapter hi. — magnetite and pyritb. Example 12, Magnetite beds, 160; Adirondack region, 160- 166; New York and New Jersey Highlands, 166-169; South Moun- tain, Penn., 169; Western North Carolina and Virginia, 169, 170; Colorado, 170, 171 ; California, 171 ; Example 13, titaniferous mag- netites, 171-175; Example 14, Cornwall, Pa., 175-180; Example 14a, Iron Co., Utah, 180; Example 15, magnetite sands, 180, 181; origin of magnetite deposits, 181-183 ; analyses of magnetites, 183 ; pyrite, 184-186 ; Example 16, pyrite beds, 184-186 ; statistics, 186 ; remarks on Cuban and Mexican iron ores, 183-188. . . . 160-188 CHAPTER IV.— Copper. Table of analyses of copper ores, 189 ; Example 16, continued, pyrite beds, 189-194; Spenceville, Cal., 195, 196; Example 17, Butte, Mont., 197-203; Gilpin Co., Colo., 203, 204; Llano Co., Texas, 204; Example 18, Keweenaw Point, Mich., 204-209; origin of the copper, 209-212; Example 19, St. Genevieve, Mo., 313, 214; Example 20, Ariz.ona Copper, 314, 215; Morenci, 215, 216; classi- fication of ores by Henrich, 316, 317; Bisbee, 217, 218; Globe, 218, 219; Santa Rita, N. M., 319; Black Range, 320; Copper Basin, 220; Crismon-Mammoth, Utah, 231, 322; Wyo., Idaho, "Wash., 222 ; Example 21, copper ores in Triassic or Permian sandstone, 322-234; Eastern States, 323, 324; Western States, 324; statistics of copper, 225 189-225 TABLE OF CONTENTS. xi PAQE CHAPTER v.— Lead Alone. Introductory and analyses of lead ores, 336 ; Example 33, At- lantic border, St. Lawrence Co., N. Y., 336, 337; Mass., Conn., and Eastern N. Y., 337; Southeastern Penn., 337; Davison Co., N. C, 338; Sullivan and Ulster Counties, N. Y., 338; Example 33, Southeastern Missouri, 338-331; statistics of lead, 333 336-332 CHAPTER VI.— Lead and Zinc. Example 34, Upper Miss. Valley, 333-337; Washington Co., Mo., 338, 339; Livingston Co., Ky., 339; Example 25, Southwest Missouri, 240-345; Example 36, Wythe Co., Va., 347-349 333-349 CHAPTER VII. — Zinc Alone, or with Metals other than Lead. Introduction : Tables of analyses of zinc ores, 350 ; Example 27, Saucon Valley, Penn., 350, 251; Example 28, Franklin Fur- nace and Sterling, N. J., 251-257; Zinc in the Rooky Mountains, 258, 259 ; in New Mexico, 359 350-359 QHAPTER VIIL— Lead and Silver. Introduction, 860; Rocky Mountain region and the Black Hais; 360, 374; New Mexico, 260-363; Example 39, Kelley Lode, 360; Lake Valley, 260-363; Colorado, 362-373; Example 30, Lead- ville, 363-366; Example 30a, Ten Mile, Summit Co., 366, 367; Ex- ample 306, Monarch District, ChaifeeCo., 268; Example 30c, Eagle River, Eagle Co., 368; Example 30d, Aspen. Pitkin Co., 268-271; Example 30e, Rico, Dolores Co., 271, 373; Example 31, Red Moun- tain, Ouray Co., 372; South Dakota, Example 30/, 272; Montana- Idaho, Example 32, Glendale, 373; Example 33a, Wood River, 373; Example 33, Wickes, Jefferson Co., 373; Example 34, Coeur d'Aletie, 374; Region of the Great Basin, 374-379; Utah, Exam- ple 35, Bingham and Big and Little Cottonwood Canons, 274, 275 ; Example 35a, Tooele Co,, 275; Example 35&, Tintic District, 275; Example 30sr, Hornsilver Mine, 275, 276; Example 33a, Car- bonate Mine, Beaver Co., 376; Example 32&, Cave Mine, Beaver Co., 276; Nevada, Example 36, Eureka, 377, 378; Arizona; CaU- fornia, 279 260-278 CHAPTER IX. — Silver and Gold. — Introductory ; Eastern Silver Mines and the Rocky Mountain Region of New Mex- ico AND Colorado. Introduction, 280; Examples 37-42, defined, 280, 281; silver and gold ores, 281-283; Example 23a, Atlantic Border, 383; Ex- ample 43, Silver Islet, Lake Superior, 383, 284; Thunder Bay, Canada, 284 ; region of the Rocky Mountains and the Black HiUs, 284-307; New Mexico, geology, 284, 285; mines, 285, 386; Colorado, geology, 286, 287 ; San Juan region, 287-293 ; Creede region, 393 ; Gunnison region, 394; Eagle Co., 394; Summit Co., 394, 395; Park, Chaffee, Rio Grande Counties, 295; Conejos Co., 296; Cus- ter Co., 296; Example 39, Bassick Mine, 296, 297; Example 39a, xii TABLE OF CONTENTS. PAGE Bull Domingo Mine, 397-399; Humboldt-Pocahontas, 399; Silver CUfl, 399, SOO; Teller Co., 300-305; Gilpin Co., 305, 306; Clear Creek Co., 306; Boulder Co., 306, 307 380-307 CHAPTER X.— Silver and Gold, Continued.— Rocky Mountain Region, Wyoming, .the Black Hills, Montana, and Idaho. Wyoming, geology, 308; South Dakota, geology, 309; the Black Hills, 309-314; Montana, geology, 314-316; Madison Co., 316, 317; Beaverhead Co., 317; Jefferson Co., 317, 318; Silver Bow Co., 318, 319; Broadwater Co., 319; Deer Lodge Co., 319; Lewis and Clarke Counties, 330; Meagher Co., 330,331; Cascade Co., 331; Flathead, Choteau, and Fergus Counties, 333, 333; Idaho, geolog}', 333; Kootenai and Lemhi Counties, 334; Custer, Boise, Alturas, and other counties, 334-337 308-337 CHAPTER XI. — Silver and Gold, Continued. — The Region op the' Great Basin, in Utah, Arizona, and Nevada. Utah, geology, 338; Ontario and other mines, 339, 330; Ex- ample 41, Silver Reef, 333, 334; Arizona, geology, 334; Apache, Yavapai, Mohave, Yuma, Maricopa, and Pin^il Counties, 335; Silver King mine, 335, 336; Graham and Cochise Counties, 336; Tombstone, 336; Pima and Yuma Counties, 336, 337; Nevada, , geology, 337; Lincoln, Ney, and White Pine Counties, 338, 339; Lander and other counties, 339, 340; the Comstock Lode, 340- 345 838-345 CHAPTER XII. — The Pacific Slope — Washington, Oregon and California. Washington, geology, 346; mines, 347; Oregon geology, 347, 348; Example 44a, Port Orford, 348, 349; Cahfornia, geology, 349, 350; Calico District, 351-353; Example 44, auriferous gravels, 353-363; river gravels, 353, 354; high or deep gravels, 354-360; general resume of geological history of gravels, 360-363 ; Example 45, gold-quartz veins, 363-375 .................. 346-375 CHAPTER XIII.— Gold Elsewhere in the United States and Canada. Example 45a, Southern Appalachians, 376-378 ; Alabama, 378, 379; Georgia, 379; South Carolina, 380; North Carolina, 380, 381 r Virginia, Maryland and the Northern States, 381-383; Example 4Sb, Ishpeming, Mich., 383; the Rainy River District, 383-385; Alaska and the Canadian Northwest, geology, 385-389 ; Example 38, Douglass Island, 390-393; Yukon Basin, 393-397; Example 45c, Nova Scotia, 397-399; gold elsewhere in Canada, 400, 401; sta- tistics, 401, 403 376-403 CHAPTER XIV.— The Lesser Metals— Aluminum, Antimony, Ar- senic, Bismuth, Chromium, Manganese. Aluminum, 403-410; antimony, 410, 411; Example 47, includ- ing California, Nevada, Arkansas, New Brunswick, 410, 411 ; Ex- TABLE OF GONTBNTS. xiii PAOB ample 48, Iron Co., Utah, 411; arsenic, 413; bismuth, 413- chro- ■ mium, 415, 416; Example 49, chromite in serpentine, 414, 415; California, 415, 416; Quebec, 416; manganese, 416-433; Exam pie 50, manganese ores in residual clay, 418-433 ; Batesville, Ark. 430-433; Panama, 433 403-433 CHAPTER XV.— The Lesser Metals, Continued.— Mercury, Nickel and Cobalt, Platinum, Tin. Mercury, ores, 434, 435 ; Example 50, New Almaden, 435, 436 ; Example 50a, Sulphur Bank, 437; Example 505, Steami oat Springs, Nev., 437; resume regarding mercury, 4.^8; nickel and cobalt, 438^41; introductory, 438-430; Example 16c, pyrrhotite beds or veins, 430, 431; Example 13a, Gap mine, Penn., Sudbury, Ont., 431-438; Example 49a, Riddle's, Oregon, 438-440; Example 33a, Mine la Motte, Mo., 440; other occurrences of nickel ores, 440, 441; platinima, 441; tin, 441, 443; Example 51, Black Hills, 443, 443; other occurrences of tin, 443, 444; Mexico, 444 434-444 CHAPTER XVI.— Concluding Remarks. Summation of such general geological relations among North American ore deposits as can be detected 445-447 APPENDIX I. — A Review op the Schemes for the Classification OF Ore Deposits. General remarks, 447, 448 ; schemes involving only the classification of veins, 448-451 ; general schemes based on forms, 451-453 ; schemes, partly based on form, partly on origin, 453-455; schemes largely based on origin, 455-457 ; schemes entirely based on origin, 457-459 ; remarks on schemes and classification of ore deposits, 459-463. . .447-468 LIST OF ILLUSTEATIONS FiaS. PAGE 1. Illustration of rifting in granite at Cape Ann, Mass. After R. S. Tarr 13 2. Open fissure in the Aubrey limestone (Upper Carboniferous), 35 miles north of Canon Diablo Station, on the A. & f. R.R. , Arizona. Photographed by G. K. Gilbert, 1893 0pp. 30 3. Normal fault at Leadville, Colo. After A. A. Blow 30 4. Reversed fault at Holly Creek, near Dalton, Ga. After C. W. Hayes 33 5. Illustration of an older vein, the Jumbo faulted by a later one (cross vein) at Newman Hill, Rico, Colo. After T. A. Rickard. 34 6. Banded vein at Newman Hill, near Rico, Colo. After J. B. Farish 36 7. Map showing the distribution of iron ores in North America 88 8. Cross-section of the Prosser iron mine near Portland, Ore., show- ing the bed of limonite between two flows of basalt. After B. T. Putnam 91 9. Section of the Hurst limonite bank, Wythe Co., Va., illustrating the replacement of shattered limestone with limonite and the formation of geodes of ore. After E. R. Benton 93 10. View of the Low Moor limonite mines, Virginia. After a photo- graph by J. F. Kemp Opp. 95 11. Geological section of the Low Moor, Va., iron ore bed. After B. S. Lyman 96 13. Ideal cross-section of Iron Hill near Waukon, Allamakee Co., Iowa 99 13. Geological section of the Amenia mine, Dutchess Co., N. Y. After B. T. Putnam 100 14. View of the Siluro-Cambrian, brown hematite bank at Baker Hill. Ala. From the Engineering and Mining Journal , . . Opp. 103 15. Map and sections of the Burden spathic ore mines. After J. P. Kimball 110 16. Clinton ore, Ontario, Wayne Co., N. Y. After C. H. Smyth, Jr. 115 17. Clinton ore, Chnton, N. Y. After C. H. Smyth, Jr 116 18. Clinton ore, Eureka mine, Oxmoor, Ala. After C. H. Smyth, Jr. 117 xvi LIST OF ILLUSTRATIONS. FIG. PAGE 19. Cross-section of the Sloss mine. Red Mountain, Ala. From the Engineering and Mining Journal H'*' 20. Map of the vicinity of Birmingham, Ala. From the Transac- tions of the American Institute of Mining Engineers 119 31. View of Cherry Valley mine, showing sandstone with underly- ing cherty clay. After F. L. Nason 0pp. 133 33. Section of the northern end of the Cherry Valley mine. After F. L. Nason 0pp. 133 33. Cross-section of the Cherry Valley mine. After F. L. Nason. 0pp. 133 34. Map of the Lake Superior region, showing the location of the iron-ore districts. From U. S. Geological Survey 136 25. Generalized section across Marquette iron range, to illustrate the type of folds. After C. R. Van Hise 139 36. Geological map of the western portion of the Marquette iron range. After Van Hise and Bayley 130 5^7. Geological map of the eastern portion of the Marquette iron range. After Van Hise and Bayley 131 28. Cross-section to illustrate the occurrence and associations of iron ore in the Marquette district, Michigan. After C. R. Van Hise 133 29. Open cut in the Republic mine, Mai-quette range, showing a horse of jasper. After H. A. Wheeler 0pp. 138 30. Plan of the Ludington ore body, Menominee district, Michigan. After P. Larsson 137 31. Geological map of the Penokee-Gogebic iron range. After Irving and Van Hise 140 32. Longitudinal and cross-section of the Ashland mine, Ironwood, Mich. , re-drawn from mine maps 143 33. Cross-section of the Colby mine, Penokee-Gogebic district, Michi- gan, to illustrate occurrence and origin of the ore. Aftet C. R. Van Hise 143 34. Map of the Minnesota iron ranges. After F. W. Denton 145 85. Geological map of the vicinity of Tower and Soudan, Minn. After Smyth and Finlay 147 36. Cross-sections of the ore bodies at Soudan, Vermilion Range, Minn. After Smyth and Finlay 149 37. Open cut at Minnesota Iron Co.'s mine, Soudan, near Tower, in south vein, looking west. After J. F. Kemp Opp. 148 38. Horizontal and vertical cross-section of the Chandler ore body at Ely, Minn. After Smyth and Finlay 150 89. View of Chandler mine, showing sinking of ground. After J. F. Kemp Opp. 149 40 General cross-section of ore body at Biwabik, Mesabi Range, Minn. After H, V, Winchell l,Hl 41. View of the Mesabi Mountain or Oliver mine, Virginia, Minn., looking southeast. After J. F. Kemp Opp. 153 42. Cross-section of Pilot Knob, Mo. From drawing by W. B. Potter 156 LIST OP ILLUSTRATIONS. xvii Pia. PAGE 43. View of open out at Pilot Knob, Mo. , showing the bedded char- acter of the iron ore. After J. F. Kemp Opp. 157 44. View of Iron Mountain, Mo., from the east. After H. A. Wheeler Opp. 158 45. Cross-section of Iron Mountain, Mo. By W. B. Potter 156 46. View of open cut and underground work in mine 31, Mineville, near Port Henry, N. Y. After J. F. Kemp Opp. 163 47. Cross-section of the Cheever iron mine, near Port • Henry, N. Y. After J. F. Kemp 163 48. Geological map of the iron mines at Mineville, near Port Henry, N. Y. After J. F. Kemp 163 49. Cross-section of ore-bodies at Mineville, near Port Henry, N. Y. , to accompany map, Fig. 48. After J. F. Kemp 164 50 and 51. Model of the Tilly Foster ore body. After F. S. Rutt- mann and J. F. Kemp 166 52. Sketch map illustrating the geological structure of the Hibernia magnetite beds, Hibernia, N. J. After J. E. Wolff 168 53. Section along Cornwall Railroad from Lebanon to Miner's Vil- lage. After E. V. dlnvilUers 176 54. Map of Cornwall mines. After E. V. d'InviUiers 177 55. Map of Ducktown, Tenn., copper mines, showing the relations and extent of the veins. After Carl Henrich 191 56. Cross-section, shaft 3, Old Tennessee mine, Ducktown, Tenn. After Carl Henrich 193 57. View of the Mary Mine, Ducktown, Tenn. , from the west. From a photograph by J. F. Kemp Opp. 194 58. Geological map of the western half of Butte district, Montana. reproduced from map of U. S. Geological Survey 198 59. Geological map, eastern half, Butte district, Montana. Idem .... 199 60. View of the Big Butte, Butte City, Mont., looking northwest across Missoula Gulch. From photograph by J. F. Kemp.. Opp. 200 61. View of the Anaconda mine, Butte, Mont. From photograph by Alexander Brown OpP- 200 62. View of the larger copper mines, Butte, Mont., looking nearly due east from the roof of the Hotel Butte. From photograph by J. F. Kemp Opp. 301 63. Contact of the older Butte granite and the later intruded Blue- bird granite as exposed in a cut on the Butte, Anaconda, Pacific R. R. Photographed by J. F. Kemp Opp. 203 64. Cross-section of the Bob-tail mines. Central City, Colo. After F. M. Endlich 304 65. Geological section of Keweenaw Point, Mich. , near Portage Lake and through Calumet. After R. D. Irving 206 66. Map of the Portage Lake district, Keweenaw Point, Mich 207 67. Cross-section in the St. Genevieve copper mine, illustrating the relations of the ore. After F. Nicholson 213 68. Section at the St. Genevieve mine, illustrating the intimate re- lations of ore and chert. After F. Nicholson 313 LIST OF ILLUSTRATIONS. xix FIG. PAGE 94. Section through the No. 2 ore chute of the Robinson mine, Ten- mile district, Colo. After S. F. Emmons 367 95. Cross-section, Queen of the West mine, Ten-mile district, Colo. After S. F. Emmons 267 96. Geological section at the Eagle River mines, Colo. After E. E. Olcott 269 97. A — Cross-section of the Delia S. mine, Smuggler Mt. , Aspen, Colo. After J. E. Spurr 370 B — Section through the Durant and Aspen mines. By D. Rohlfing 270 98. View of the Bunker Hill and Sullivan mines, Wardner, Idaho. Photographed by E. E. Olcott 0pp. 274 99. View of town of Mammoth, Tintio district, Utah. Photographed by L. E. Riter, Jr 0pp. 275 100. Bullion and Beck mine and mill. Eureka, Tintic district, Utah. Photographed by L. E. Riter, Jr 0pp. 275 101. Section at Eureka, Nev. After a plate by J. S. Curtis 378 102. Geological sketch-map of the Telluride district, Colo. After Arthur Winslow 389 103. Geological cross-sections of strata and veins at Newman Hill, near Rico, Colo. After J. B. Farish 391 104. Geological cross-sections of strata and veins at Newman Hill, near Rico, Colo. After J. B. Farish 392 105. Cross-section of the Bassick mine, near Rosita. After S. F. Emmons 298 106. Cross-section of the Bull-Domingo mine, near Silver Cliff, Colo. After S. F. Emmons 298 107. Cross-section of the Humboldt-Pocahontas vein, near Rosita, Colo. After S. F. Emmons 399 108. Geological map of Cripple Creek, Colo. TJ. 8. Geological Survey. Geology by Cross and Matthews 301 109. View of Cripple Creek, Colo., from Mineral Hill; Gold Hill in background. Photographed by J. F. Kemp Opp- 303 110. View of Battle Mt., Victor, Colo., Portland group of mines and Independence mine. Photographed hy J. F. Kemp Opp. 302 111. Map of the Independence and Washington claims. Cripple Creek, Colo. After R. A. F. Penrose 303 113. Stereogram of the Annie Lee ore-chute, Victor, Colo. After R. A. F. Penrose 304 113. Geological section of the Black Hills. After Henry Newton 309 114. Geological section of the strata in the Northern Black Hills, 8. D. After John D. Irving 310 115. Plan and erosssection of the Cambrian, siUoeous gold-ore de- posits in the Black Hills, S. D. After John D. Irving 311 116. Plan and section. Mail and Express mine, to illustrate the sili- ceous gold ores of the Black Hills, S. D. After John D. Irving. 313 117. View of Green Mt., Black Hills, S. D., a laccolite of phonolite. LIST OF ILLUSTRATIONS. xxi FIG. PAGE 140. Generalized section of a deep gravel bed, with technical terms. After R. E. Browne 355 141. Section of Forest Hill Divide, Placer Co., CaUf., to illustrate the relations of old and modern lines of drainage. After R. E. Browne 359 143. North Star vein, Grass Valley, Calif., showing quartz vein in brecciated and altered diabase. After W. Lindgren 0pp. 363 143 and 144. Ore shoots of Nevada City and Grass Valley mines, Calif. After W. Lindgren -. 364 145. Section of the Pittsburg vein, ninth level, Nevada City district, Calix. From U. S. Geological Survey. 365 146. Geological section at Merrifield vein. Providence claim, Nevada City district, CaUf. After W. Lindgren 366 147. Cross-section of vein in St. John mine, fifth level, Nevada City district, Calif. After W. Lindgren. . , ^ 366 148. Cross-section of the Maryland vein, in slope abofe 1500-foot level. Grass Valley district, Calif. After W. Lindgren 367 149. Cross-section of the Brunswick vein, on the 700-foot level. Grass Valley district, Calif. After W. Lindgren 868 150. Western half of Geological map of the Yukon Gold Belt, and ad- jacent regions. (See Fig. 151) 386 151. Eastern half of Geological map of the Yukon Gold Belt, and ad- jacent regions. After J. E. Spurr . ; 387 152. Map of the Juneau mining district, Southeast Alaska. After G. F. Becker 392 153. Sketch map of Nova Scotia Gold Fieldc. After E. Gilpip 398 154. Cross-section of a Bauxite deposit in Georgia. After G. Willard Hayes 405 155. Sections of the Crimora manganese mine, Virginia. After C. E. Hall '. 418 156. Geological sections illustrating the formation 01 manganese ores in Arkansas. After R. A. F. Penrose 419 157. The Turner mine, Batesville region, Arkansas. After E. A. F Penrose . . , 420 158. Section of the Great Western cinnabar mine. After G. F Becker 436 159. Map and section of Gap Nickel mine, Lancaster Co., Penn. After J. F. Kemp 433 160. Geological section-map of the Sudbury district, Ontario. After by T. L. Walker. , 435 161 and 163. View of Copper Cliff mine, Sudbury, Ontario. Photo- graphs by T. G. White 0pp. 436 163. Horizontal section of the Etta granite knob, Black Hills, S. D. After W. P. Blake 442 ABBREVIATIONS. Amer. Assoc. Adv. Sci., or A. A. A. iST^Proceedings of the American As- sociation for the Advancement of Science. Amer. Geol. — American Geologist. Minneapohs, Minn. Amer. Jour. Sci. — American Journal of Science, also known as Silliman's Journal. Fifty half- yearly volumes make a series. The Journal is now (1893) in the third series. In the references the series is given first, then the volume, then the page. Ann. des Mines — Annales des Mines. Paris, France. Bost. Soe. Nat. Hist. — See Proceedings of same. Bull. Geol. Soc. Amer. — Bulletin of the Geological Society of America. Bull. Mus. Comp. Zool. — Bulletin of the Museum of Comparative Zoology, Harvard University. Cambridge, Mass. B. und H. Zeitung. — Berg- und Huettenmannische Zeitung. Leipzig, Germany. Neues Jahrb. — Neues Jahrbuch filr Mineralogie, Geologie und Paleeon- tologie, often called Leonhard's Jahrbuch. Stuttgart, Germany. Oest. Zeit. f. Berg. u. Huett. — Oesterreichische Zeitschrift fur Berg- und Huettenwesen. Vienna, Austria. Philos. Mag. — Philosophical Magazine. Edinburgh, Scotland. Proc. Amer. Acad. — Proceedings of the American Academy of Arts and Sciences. Boston, Mass. Proc. and Trans. N. S. Inst. Nat. Sci. — Proceedings and Transactions of the Nova Scotia Institute of Natural Science. Halifax, Nova Scotia. Proc. Bost. Soc. Nat. Hist. — Proceedings of the Boston Society of Natural History. Boston, Mass. Proc. Colo. Sci. Soc. — Proceedings of the Colorado Scientific Society. Denver, Colo. Raymond's Reports. — Mineral Resources West of the Eocky Mountains, Washington, 1867-1876. The first two volumes were edited by J. Ross Browne, the others by R. W. Raymond, Trans. Amer. Inst. Min. Eng, — Transactions of the American Institute of Mining Engineers. Trans. Min. As.ioe. and Inst., Cornwall. — Transactions of the Mining As- sociation and Institute of Cornwall. Tuckingmill, Camborn, England. xxiv ABBREVIATIONS. Trans. N. Y. Acad, of Sci. — Transactions of the New York Academy of Sciences, formerly the Lyceum of Natural History. Zeit. d. d. g. Ges. — Zeitschrift der deuischen geologischen Gesellschaft. Berlin, Germany. Zeitsch. f. B., H. und S. I'm, P. St.— Zeitschrift fur Berg-, Huetten-, und Salinenwesen im Preussischen Sta.at. Berlin, Germany. Zeitsehr. f. Krys. — Zeitschrift fur Krystallographie. Munich, Germany. Zeitsch f. prakt. Geol. — Zeitschrift filr praktische Geologie. Berlin, Ger- many. The remaining abbreviations are deemed self-explanatory. The num- bering of the paragraphs is on the following principle: The first digit refers invariably to the part of the book, the second digits to the chapter, and the last two to the paragraph of the chapter. PART I. INTRODUCTORY. CHAPTER I. GENERAL GEOLOGICAL FACTS AND PRINCIPLES. 1.01.01/ In the advance of geological scignce the stand- points from which the strata forming the earth's crust are re- garded necessarily change, and new points of view are estab- lished. In the last few years two have become especially prominent, and there are now tw o sharply contrasted positions from which to obtain a conception of the structure and develop- ment of the globe. The first is the physical, the second the biological. For example, we consider the surface of the earth as formed by rocks, differing in one part and another, and these different rocks or groups of rocks are known by different names. The names have no special reference to the animal remains found in them, but merely indicate that series of re- lated strata form the surface in particular regions. On the other hand, the rocks are also regarded as having been formed in historical sequence, and as containing the remains of organ- isms characteristic of the period of their formation. They illus- trate the development of animal and vegetable life, and in this way afford materials for historical-biological study. In the original classification, the biological and historical considera- tions are all-important. But when once the rocks are placed in their true position in the scale, and are named, these considera- tions, for many purposes, no longer concern us. The forma- tions are regarded simply as members in the physical constitu- tion of the outer crust. The International Geological Congress held in Berlin in 1885 expressed these different points of view in two parallel and equivalent series of geological terms, which ' The numbers at the beginning of the paragraphs are so arranged that the first figure denotes the part of the book, the next two figures the chap- ter, and the last two the paragraph. Thus 1.06.21 means Part I., Chapter VI., Paragraph 21 under Chapter VI. KEMP'S ORE DEPOSITS. are tabulated on p. 4. They are now very generally adopted. For clearness in illustration, the equivalent terms employed by Dana are -appended. Biological Terms. Physical Terms. Dana's Terms. Illustrations. Era. Group. Time. Paleozoic. Period. System. Age. Devonian. Epoch. Series. Period. Hamilton. Age. Stage. Epoch. Marcellus. The United States Geological Survey divides as follows : Era and System, Period and Group, Epoch and Formation. In considering the ore deposits of the country, we employ only the physical terms. We understand, of course, the chronological position of the systems in historical sequence, but it is of small moment in this connection what may be the forms of life in- closed in them. The purely physical character of the rocks — whether crystalline or fragmental; whether limestone, sand- stone, granite or schists; whether folded, faulted, or undis- turbed — ^are the features on which we lay especial stress. In all the periods the same sedimentary rocks are repeated, and in the hand specimen it is almost always impossible to distin- guish those of different ages from one another. The classifi- cation, briefly summarized, is as follows : 1.01.02. Archean Group. — I. Laurentian System. II. Huronian System. Additional subdivisions have been intro- duced by Canadian and Minnesota geologists (Animikie, Mont- alban, etc.), and it is a growing custom to call all those which are sediments or later than sediments, especially in the region of the Great Lakes, by the name of Algonkian. (See discus- sion under Example 9.) Paleozoic Group. — III. Keweenawan System. (This may belong with the Archean.) IV. Cambrian System: (a) Georgian Stage; ip) Acadian Stage; (c) Potsdam Stage. V. Lower Silurian System. {A) Canadian Series: (a) Calcifer- ous Stage; (&) Chazy Stage. (This. will probably experience revision.) {B) Trenton Series: (a) Trenton Stage; (h) Utica Stage; (c) Cincinnati or Hudson River Stage. VI. Upper Silurian System. (J.) Niagara Series : (a) Medina Stage; (6) Clinton Stage; (c) Niagara Stage. {B) Salina Series. (C) Lower Helderberg Series. VII. Devonian System. (J.) Oris- kany Series. {B) Corniferous Series ; (a) Cauda-Galli Stage: QENEHAL GEOLOGICAL FACTS AND PRINCIPLES. 5 (fo) Schoharie Stage; (c) Corniferous Stage. (C) Hamilton Series: (a) Marcellus Stage; (&) Hamilton Stage; (c) Genesee Stage. (Z)) Chemung Series: (a) Portage Stage; (fe) Chemung Stage. VIII. Carboniferous System. {A) Sub-carboniferous or Mississippian Series. {B) Carboniferous Series. (C) Permian Series. Mesozoic Group.— IX. Triasaic Sj-stem. X. Jurassic Sys- tem. IX. and X. are not sharply divided in the United States, and we often speak of Jura- Trias. A stratum of gravel and sand, along the Atlantic coast, that contains Jurassic fossils has been called the Potomac formation by McGee. XL Cre- taceous System. ' Subdivisions differ in different parts of the country. Atlantic Border: (a) Raritan Stage; ih) New Jer- sey Greensand Stage. Gulf States: (a) Tuscaloosa Stage; (6) Eutaw Stage ; (c) Rotten Limestone Stage ; (d) Ripley Stage. Rocky Mountains: (a) Comanche Stage; (6) Dakota Stage; (c) Benton Stage; (d) Niobrara Stage; (e) Pierre Stage; (/) Fox Hills Stage; {g) Laramie Stage. Stages (c) and {d) are sometimes collectively called the Colorado Stage; while (e) and (/)are grouped as the Montana Stage. Pacific Coast: (a) Shasta Stage; (&) Chico Stage. Cenozoic Group. — XII. Tertiary System. Gulf States. {A) Eocene Series: Midway, Lignitic, Lower Claiborne, Clai- borne. Jackson and Vicksburg Stages. {B) Oligocene, want- ing. (C) Miocene Series, Chattahoochee, Chipola and Chesa- peake Stages. (-D) Pliocene Series: Floridian Stage. Interior Region. {A) Eocene Series : Puerco, Torrejon, Wasatch, Wind River, Bridger and Uinta Stages. {B) Oligocene Series : White River Stage. (C) Miocene Series* John Day, Deep River, and Loup Fork Stages. {D) Pliocene Series: Good-night (Palo Duro) and Blanco Stages. Pacific Coast. The Eocene is called the Tejon. Miocene and Pliocene are used for the others. XIII. Quaternary System. {A) Glacial Series. {B) Champlam Series. (C) Terrace Series. {D) Recent Series. Pleistocene is sometimes employed as a name for the early Quaternary, especially south of the Glacial Drift. In accord with the practice of the U. S. Geological Survey, the Tertiary is now generally divided into the Eocene and the Neocehe (in- cluding Oligocene, Miocene and Pliocene) series. 6 KEMP'S ORE DEPOSITS. Other terms are also often used, especially when we do not wish to speak too definitely. "Formation" is a word loosely employed for any of the above divisions. "Terrane" is used much in the same way, but is rather more restricted to the lesser divisions. A stratum is one of the larger sheet-like masses of sedimentary rock of the same kind; a bed is a thinner subdivision of a stratum. "Horizon" serves to indi- cate a particular , position in the geological column; thus, speaking of the Marcellus Stage, we say that shales of this horizon occur in central New York. 1.01.03.- The rock species themselves are classified into three great groups — the Igneous, the Sedimentary, and the Metamorphic. The Igneous (synonymous terms, in whole or in part : massive, eruptive, volcanic, plutonic) include all those which have solidified from a state of fusion. They are marked by three types of structure — the granitoid, the porphyritic, and the glassy, depending on the circumstances under which they have cooled. Under the first type of structure come the granites, syenites, diorites, gabbros, diabases, and peri- dotites; under the second, quartz-porphyries, rhyolites, por- phyries, trachytes, porphyrites, andesites, and basalt; under the third, pitchstone, obsidian, and other glasses. The Sedimentary rocks are those which have been deposited in water. They consist chiefly of the fragments of pre-existing rocks and the remains of organisms. They include gravel, conglomerate, breccia, sandstone^ — ^both argillaceous and cal- careous—shales, clay, limestone, and coal. In volcanic dis- tricts, and especially where the eruptions have been subma- rine, extensive deposits of volcanic lapilli and fine ejectments have been formed, called tuffs. With the sedimentary rocks we place a few tbat have originated by the evaporation of solu- ■ tions, such as rock salt, gypsum, etc. The Metamorphic rocks are usually altered and crystallized members of the sedimentary series, but igneous rocks are known to be subject to like change, especially when in the form of tuffs. They are all more or less crystalline, more or less distinctly bedded or laminated, of ancient geological age. or in disturbed districts. They include gneiss, crystalline schists, quartzite, slate, marble, and serpentine. GENERAL GEOLOGICAL FACTS AND PRINCIPLES. ". After £. brief topographical survey, we shall employ the above terms to summarize the geological structure of the United States. The several purely artificial territorial divi- sions are made simply for convenience. Nothing but intelli- gent travel M^ill perfectly acquaint one with the topographical and geological structure of the country, and in this connection Macfarlane's "Geological Eailway Guide" and a geological map are indispensable. 1.01.04. On the east we note the great chain of the Appa- lachians, with a more or less strongly marked plain between it and the sea. This is especially developed in the south, and is now generally called the Coastal Plain. It is of late geologi- cal age, and contains the pine barrens and seacoast swamps. The Appalachians themselves consist of many ridges, running on the north into the White Mountains, the Green Mountains, and the Adirondacks. Farther south the Highlands of New York and New Jersey, the South Mountain of Pennsylvania, the Alleghenies,the Blue Ridge, and the other southern ranges make up the great eastern continental mountain system. In western New York and Ohio we find a rolling, hilly country; in Kentucky and Tennessee, elevated tableland, with deeply worn river valleys. Indiana, Illinois, Iowa, and Missouri con- tain prairie and rolling country, more broken in southern Mis- souri by the Ozark, uplift. la Michigan, Wisconsin, and Minne- sota, the surface is rolling and hilly with numerous lakes. In Arkansas, Louisiana, and Mississippi there are bottom lands along the Mississippi and Gulf with low hills back in the interior. Across Arkansas and Indian Territory runs the east and west Ouachita uplift. West of these States comes the region of the great plains, and then the chain of the Rocky Mountains, consisting of high, dome-shaped peaks and ridges, with ex- tended elevated valleys (the parks) between the ranges. Some distance east of the main chain are the Black Hills, made up of later concentric formations around a central, older nucleus. To the east lies also the extinct volcanic district of the Yellowstone National Park. In western Colorado, Utah, and New Mexico, between the Rocky Mountains and the Wasatch, is the Colorado plateau, an elevated tableland. This is terminated by the north and south Wasatch range,' and is traversed east and west by the Uintah range. To the 8 KEMP'S ORE DEPOSITS. west lies the region called the Great Basin, characterized by alkaline deserts, and subordinate north and south ranges of mountains. Next comes the chain of the Sierra Nevada, and lying between it and the Coast range is the great north and south valley of California. This rises in the comparatively low Coast range, which slopes down to the Pacific Ocean. To the north, these mountains extend into eastern Oregon and Washington, with forests and fertile river valleys. These topographical features are important in connection with what follows, for the reason that the ore deposits especially favor mountainousj regions. Mountains them- selves are due to geological disturbances — upheaval, folding, faulting, etc. — and are often accompanied by great igneous outbreaks. They therefore form the topographical surround- ings most favorable to the development of cavities, waterways, and those subterranean, mineral-bearing circulations which would fill the cavities or replace the rock with useful min- erals. 1.01.05. Geological Outline. I. New England, New York, New Jersey, and Eastern Pennsylvania District. — In New England and northern New York the Archean is espe- cially developed, forming the White Mountains, the Adiron- dacks, and the Highlands of New York and New Jersey. These all consist of granite and other igneous rock, of gneiss, and of crystalline schists. There are also great areas of meta- morphic rocks whose true age may be later. The Green Moun- tains are formed of such, and were elevated at the close of the Lower Silurian. In New England there are small, scattered exposures of the undoubted Paleozoic (Devonian, Carbonif- erous). In eastern New York, and to some extent in New Jer- sey and eastern Pennsylvania, the entire Paleozoic, except the Carboniferous, is strongly developed. Up and down the coast there are narrow north and south estuary deposits of red Jura- Trias sandstone, which are pierced by diabase eruptions. The Cretaceous clays are strong, and the Tertiary strata occur at Martha's Vineyard, in Massachusetts, while over all, as far south as Trenton, is found the glacial drift. Between the Archean ridges of the Highlands, and the first foldings of the Paleozoic on the west is found the so-called Great Valley, which also runs to the south and is a very important topo- GENERAL GEOLOGICAL FACTS AND PRINCIPLES. 9 graphic and geologic feature. It follows the outcrop of the Siluro-Cambrian limestones, to whose erosion it is due. II. Eastern- Middle and Southeastern Coast District. — The low plains of the coast are formed by Quaternary, Terti- ary, and Cretaceous, consisting of gravel, sand, shell beds, and claj'. Inland there are exposures of Jura- Trias, as ia the north. The Archean crystalline rocks are also seen at numer- ous points not far from the ocean. Florida is largely made up of limestones, with a mantle of calcareous sand. III. Allegheny Region and the Central Plateau. — The Appalachian mountain system, from New York to Alabama, consists principally of folded Paleozoic (largely Carboniferous), with Archean ridges on its eastern flank. There is an enor- mous development of folds, with northeast and southwest axes. On the west they are succeeded by the plateau region of Ken- tucky and Tennessee, chiefly Paleozoic. Along central latitudes the Archean does not appear again east of the Mississippi. IV. Region of the Great Lakes. — In Michigan, Wiscon- sin, and Minnesota the Archean rocks are extensively devel- oped, both Laurentian and Huronian. Around Lake Superior are found the igneous and sedimentary rocks of the Keweena- wan, followed by the lower Paleozoic. Lake Michigan and Lake Huron are surrounded by Silurian, Devonian, and Car- boniferous; Lake Erie by Devonian; Lake Ontario, by Silu- rian. Eunning south through Ohio, we find an important fold known as the Cincinnati uplift, with a north and south axis. It was elevated at the close of the Lower Silurian. In the lower peninsula of Michigan and in eastern Ohio and western Pennsylvania the Carboniferous is extensively developed. V. Mississippi Valley. — The headwaters of the Mississippi are in the Archean. It then passes over Cambrian and Silu- rian strata in Minnesota, Wisconsin, northern Iowa, and Illi- nois, which in these States lie on the flanks of the Archean "Wisconsin Island" of central Wisconsin. These are suc- ceeded by subordinate Devonian, and in Southern Iowa, Illi- nois, and Missouri by Carboniferous. In southern Missouri the Lower Silurian forms the west bank. Thence to the Gulf the river flows on estuary deposits of Quaternary age, with Tertiary and Cretaceous farther inland. VI. The Gulf Region. — The Gulf States along the water 10 KEMP'S ORE DEPOSITS. front are formed by the Quaternary. This is soon succeeded inland by very extensive Tertiary beds, vyhich are the princi- pal formation represented. VII. The Great Plains. — West of the Paleozoic rocks of the States bordering on the Mississippi is found a broad strip of Cretaceous running from the Gulf of Mexico to and across British America, and bounded on the west by the foothills of the Rocky Mountains. A few Tertiary lake deposits are found in it. Quite extensive Triassic rocks are developed on the south. The surface is a gradually rising plateau to the Rocky Mountains. VIII. Region of the^ Rocky Mountains, the Black Hills, and the Yellowstone National Park. The Rocky Mountains rise from the prairies in long north and south ranges, consist- ing of Archean or Algonkian axes with the Paleozoic in relatively small amount in Colorado, but present in a large cross- section in Montana. There is abundant Mesozoic on the east and west flanks. ' In the parks are found lake deposits of Ter- tiary age. ' There a're also great bodies of igneous rocks, which attended the various upheavals. The principal upheavals began at the close of the Cretaceous. The outlying Black Hills consist of au elliptical Archean core, with concentric Paleozoic and Mesozoic strata laid up around it. The National Park consists chiefly of igneous (volcanic) rocks in enormous development. IX. Colorado Plateau. — ^Tfae Rocky Mountains shade out on the west into a great elevated plateau, extending to central Utah, where it is cut off by the north and south chain of the Wasatch. The Uintah Mountains are an east and west chain in its northern portion. The rocks on the north are chiefly Terti- ary, with Mesozoic and Paleozoic in the mountains. To the south are found Cretaceous and Triassic strata, with igneous rocks of great extent. The principal upheaval of the Wasatch began at the close of the Carboniferous, and seems still to be in progress. X. Region of the Or eat Basin. — Between the Wasatch and the Sierra Nevada ranges is found the Great Basin region, once lake bottoms, now very largely alkaline plains of Qua- ternary age. The surface is diversified by subordinate north and south ranges, formed by great outflows of eruptive rocks. GENERAL GEOLOGICAL FACTS AND PRINCIPLES. H and by tilted Paleozoic, The ranges are extensively broken and the stratified rocks often lie in' confused and irregular positions. There is no drainage to the ocean. XI. Region of the Pacific Slope. — The depression of the Great Basin is succeeded by the heights of the Sierra Nevada. On the west the Sierras slope down into the Central Valley of California. The flanks are largely metamorphosed Jurassic and Cretaceous rocks .with great developments of igneous out- flows. The surface rises again in the Coast ranges, which slope away farther west to the ocean. In addition to the Jurassic and Cretaceous, the Tertiary and Quaternary are also devel- oped, and in the Coast ranges are many outflows of igneous rock. The principal upheaval of the Sierra Nevada began at the close of the Jurassic, that of the Coast range at the close of the Miocene Tertiary. XII. Region of the Northwest. — Wa,&hm^on and Oregon, along the coast, arei formed by Cretaceous and Tertiary strata similar to California. But inland, immense outpourings of igneous rocks cover the greater portion of both States and ex- tend into Idaho. On the north the Carboniferous is extensive, running eastward into Montana. Quaternary and Tertiary lake deposits are also not lacking. 1.01.06. On the Forms Assumed by Rock Masses. — All sedimentary rocks have been orginally deposited in beds, ap- proximately horizontal. They are not of necessity absolutely horizontal, because they may have been formed on a sloping bot- tom, or in a delta, in both of which cases an apparent dip ensues. We find them nOw, however, in almost all cases changed from a horizontal position by movements caused primarily by the compressive strain in the earth's crust. Beds thus assume folds known as monoclines, anticlines, and synclines. A monocline is a terrace-like dropping of a bed without changing the direction of the dip. There is usually a zone, more or less shattered, along the folded portion, and such a zone may become a storage receptacle. Monoclines of a gentle character in Ohio, which have been detected by Orton in stud- ies of natural gas, have been called "arrested anticlines." An anticline is a convex fold with opposing dips on its sides, while a syncline is a concave fold with the dips on its sides coming together. We speak of the axis of a fold, and this 12 KEMP'S ORE DEPOSITS. marks the general direction of the crest or trough. The axis is seldom straight for any great distance. Folds are often broken and faulted across the strike of their axes, and this causes what is called a "pitch" of the axes and makes the original dips run diagonally down on the final one. Folds are the primary cause of the phenomena of dip and strike. Hori- zontal beds have neither. A dome-like elevation of the beds, with dips radiating in every direction from its summit, is called a quaquaversal, but it is a rare thing. An anticline or syncline with equal dips on opposite sides of its axis is called , a normal fold. If the dip is steeper on one side than on the other, it is an overthrown fold ; if the sides are crushed to- gether, it is a collapsed, or sigmoid fold. Igneous rocks are in the form of sheets (the term "bed" should be restricted to sedimentary rocks), knobs or bosses, necks, laccolites, and dikes. A sheet is the form naturally as- sumed by surface flows, and by an igneous mass which has been intruded between beds. It has relatively great length and breadth as compared with its thickness, and coincides with its Avails in dip and strike. A knob, or boss, is an irregu- lar mass, of approximately equal length and breadth, which may be related in any way to the position of its walls. Such masses are often left projecting by erosion. A neck is the filled conduit of a volcano, which sometimes remains after the over- lying material has been denuded. A laccolite is a lenticular sheet which has spread between beds laterally from its conduit, and thus has never reached the surface, unless revealed by sub- sequent erosion. A dike is a relatively long and narrow body of igneous rock which has been intruded in a fissure. It is analogous to a vein, but the term "vein" ought not to be ap- plied to an undoubtedly igneous rock. Some granitic mixtures, however, of quartz, feldspar, and mica, leave us yet in uncer- tainty as to whether they are dikes or veins. (See Example 51. ) From the above it will be seen at once that bosses, knobs, and necks may be practically indistinguishable. CHAPTEE II. THE FORMATION OF CAVITIES IN ROCKS AND THEIR SECOND- ARY MODIFICATION — SUBTERRANEAN WATERS. 1.02.01. Tension Joints. — In the contraction caused by cool- ing, drying, or hardening, both igneous and sedimentary rocks break into more or less regular masses along division planes, called joints, or diaclases. Numerous cracks and small cavities result. Basaltic columns, or the prismatic masses, formed by the separation, in cooling and consolidating, of the heavier basic rocks, along planes normal to the cooling surface, are good illustrations of the first. Larger manifestations of them often become filled with zeolites, calcite, and other secondary B Fig. 1. — Illustration of rifting in granite at Cape Ann, Mass. After R. S. Tarr. Amer. Jour, of Sci., April, 1891. minerals. Granitic rocks and porphyries break up less regu- larly from the same cause, but still exhibit prismoids and polygonal blocks and benches.' Large cracks have been re- ferred to this cause, which have afterward formed important receptacles for ores. (See Example 11a.) The nature of the strain which produces the Assuring makes ' J. P. Iddings' paper on "The Columnar Structure in the IgneoTis Rocks on Orange Mountain, N. J.," Amer. Jour. Sci., III., xxxi, 320, is an cKce' lent discussion. 14 KEMP'S ORE DEPOSITS. the term "tension joint" an excellent name for them/ There are, however, other varieties of tension joints. .Sedimentary rocks, that contain a large quantity of water when first formed, may lose it in whole or in part, and may shrink and crack for this reason, precisely as does the mud on the bottom of a dried puddle. Ledges in many parts of thp world are exposed during the day to a hot sun, and during the night cool down to a com- paratively low temperatvire, The alternate expansion and con- traction may produce tensional stresses leading to the produc- tion of joints. The concentric surfaces of parting which are so often displayed in granite quarries, and which resemble the coats of an onion, have heen referred to this' cause. When stratified rocks become folded into anticlines and synclines, tensional strains are developed in the upper layers of the anti- cline, and the lower layers of the syncline, respectively above •and below the surface of no strain. Eupture almost always results, and cracks or joints are produced, which run parallel with the axis of the fold. Cross-folding may then develop an- other series at an angle with the first. 1.02.02. Cleavage, Fissility and Compression Joints. — In speaking of the effects of pressure upon rocks, it is in many respects convenient to follow again the nomenclature of Van Hise, as established in the paper last cited, ^ and to distinguish at the outset between cleavage and fissility. Cleavage is the "capacity present in some rocks to break in some directions more easily than in others;" whereas fissility is "a structure in rocks by virtue of which they are already separated into paral- lel laminsB in a state of nature." Fissility is therefore practi- cally a development of joints on a very extensive and closely set scale, and chiefly in one direction. Cleavage, on the other hand, does not necessarily imply cavities and has not a very important bearipg on the present discussion. A case has been met in the granites of Cape Ann, however, that deserves men- tion. The granites are known to possess a tendency to split along certain planes that greatly facilitates the operations of the workmen. R. R. Tarr discovered by microscopic study, ' C. R. "Van Hise, "Principles of North American Pre-Cambrian Geol- ogy," XVI Annual Report Director U. S. Geological Survey, Part I., p. 668. 2 Op. cit, p. 633. ON THE FORMATION OF CAVITIES IN BOOKS. 15 that coincident with this "rifting" there was a minute breccia- tion that had no connection with the cleavage of the component minerals or their bounding surfaces. The brecciation has manifestly resulted from compression, and it is obvious that its presence made the granite much more permeable to water. A rock of this character, if in a region of ore deposition, would quite readily become impregnated. Both the joints produced by cooling and those foi'med by drying and consolidation may be afterward modified or increased by rock movements, and still different ones may be brought about independently of either. Indeed, it is a growing belief among observers, that even the joints in sedi- mentary strata, which have been usually referred to contrac- tional strains during consolidation, are the products of pressure or of other dynamical causes, external to the rock mass itself. It may be a very difiicult matter to differentiate the effect of one from that of the other, but pressure and torsion would naturally occasion displacement, if only on a microscopic scale. W. 0. Crosby has suggested the undulatory tremor of an earthquake as of possible importance. The experiments of Daubree indicated that pressure would produce joints, and that in a homogeneous medium two sets would result at right an- gles with each other, and each at 45° with the direction of the pressure. This theoretical regularity is not met in nature, alike from the heterogeneous character of rocks and from the complexity of the strains to which they are subject. G. F. Becker has sought in the several recent papers cited below to analyze in a mathematical way the theoretical application and effects of such strains. Torsional stresses referred to above have been suggested as having important bearings on natural phenomena, and especially since the experimental work of Daubree along these lines, but Becker is led to question their extended application to rocks. As regards the, finer textural characteristics of certain joint surfaces, J. B. Woodworth has contributed some very interesting observations, which, it is to be hoped, will be ex- tended to a wide series of rocks. In certain slaty rocks near Boston, the joint surfaces for a limited area exhibited small undulations, which diverge from a central axis, like the branches of a feather, but which then bend in curved surfaces 16 KEMP'S ORE DEPOSITS. of much larger development, so as to form somewhat extended corrugations. The author remarks the resemblance which the distribution of certain great fractures in the earth's crust bears to these hand specimens, a suggestion that might be tested in fractured areas containing veins. It is manifest that the passage from joints, properly speaking, and as outlined above, to slaty cleavage, schistosity and dy- namic effects, that are the results of many small fractures and shearing surfaces, is a gradual one, and that tbe two are inti- mately connected. Tbe references below, therefore, embrace both, although schistosity is but briefly referred to here, as its connection is not particularly close with the origin of ore bodies, however much it may afterward affect them.' 1.03.03. Cavities Formed by More Extensive Movements in the Earth's Crust. — The strains produced by compression in the outer portion of the earth are by far the most important causes of fractures. The compression develops a tangential stress which is resisted by the archlike disposition of the crust. (By the term "crust" is simply meant the outer portion of the 1 G. F. Becker on the production of fissures. See paper on "The Struc- ture of a Portion of the Sierra Nevada of California," Bulletin Geological Society of America, II. 49, 1891; also "Finite Homogenous Strain, Flow andi^upture of Rocks," Idem., IV. 13, 1893; "The Finite Elastic Stress- strain Function," Amer. Jour. Sci., Nov., 1893, p. 337. The above are rather mathematical for the general reader and the following are less so. " The Torsional Theory of Joints," Trans. Amer. Inst. Min. Eng., XXIV. 130, 1894; "Schistosity and Slaty Cleavage," Journal of Geology, XV. 429, 1896; " Eeconnoissance of the Gold Fields of the Southern Appalachians," XVI Ann. Rep. Dir. U. 8. Geol. Survey, Part III., 365-372; W. C. Crosby, "Absence of the Joint Structure at Great Depths,'' Geol. Maga- zine, Sept., 1881, p. 416; "Classification and Origin of Joint Structures," Proc. Boston Soc. Nat. Hist., XXII. 73, 1883; "On the Joint Stmcture of Rocks," Technology Quarterly, 1890; "The Origin of Parallel and Inter- secting Joints, Idem., VI. 330, 1893; also in Amer. Geologist, Dec, 1893, 368; G. K. Gilbert, "On the Origin of Jointed Structure," Amer. Jour. Sci., July, 1883, 50; J. Le Conte, "Origin of Jointed Structure in Undis- turbed Claj' and Marl Deposits," Amer. Jour. Sci., III., xxiii. 233; W. J. McGee, "On Jointed Structure," Amer. Jour. Sci., III. xxv. 1.52, 476. An excellent bibliography on slaty cleavage up to 1885 will be found in a paper by Alfred Harker, in Rep. British Assoc, for the Advancement of Science, 1885, 813, and upon this and other kindred subjects, Daubree's Etudes Synthetiques de Geologie Experimentale, 1879, Part I. ; Sub Part II., Chaps. I. -IV. ON THE FORMATION OF CAVITIES IN ROOKS. 17 globe without reference to the character of the interior. ) Where there is insufficient support, gravity causes a sagging of the material into synclinals, which leave salient anticlinals be- tween them. Where the tangential strain is also greater than the ability of the rocks to resist, they are upset and crumpled into folds from the thrust. Both kinds of folds are fruitful causes of fissures, cracks, and general shattering, and every slip from yielding sends its oscillations abroad, which cause breaks along all lines of weakness. The simplest result, either from sagging or from thrust, is a fissure, on one of whose sides the wall has dropped, or on the other of which it has risen, or both, aa will be more fully described under "Faults." If the rocks are firm and qiiite thicklj' bedded, as is the case Avith lime- stones and quartzites, the separation is cleanly cut ; but if they are softer and more yielding, they are sheared downward on the stationary or lifting side, and upward on the one which relatively sinks. Such fissures may pass into folds along their strike, as at Leadville, Colo. 1.02.04. A phenomenon which is especially well recognized in metamorphic regions, and which is analogous to those last cited, is furnished by the so-called "shear zones." A faulting movement, or a crush, may be made apparent in rocks of this character by changes in mineralogical composition and structure, as well as by clearly fractured rocks. Massive diabases, for in- stance, pass into hornblende schists or amphibolites for limited stretches. Garnets and other characteristically metamorphic minerals appear, and pyroxenes alter to amphiboles. Strains are manifested in the optical behavior of the minerals in thin sections of specimens taken from such localities. These crushed strips, or shear zones, may be formed with very slight displacement, but they afford favorable surroundings for the formation of ore bodies. This conception of the original condi- tion of a line of ore deposition is a growing favorite with recent writers, and combined with the idea • of replacement is often applicable. Fahlbands, which are very puzzling prob- lems, may have originated as shear zones. 1.03.05. A more extended effect is produced by the mono- cline, which has a double line of shattered rock marking both the crest and foot of its terrace. Anticlines and synclines occasion the greatest disturbances. Comparatively brittle 18 KEMP'S ORE DEPOSITS. materials like rocks cannot endure bending without suffering extended fractures. When strained beyond their limit of resist- ance, along the crest of an anticline, and in the trough of a syn- cline, cracks and fractures are formed which radiate from the axis of each fold. As these open upward and outward in anti- clines, they become the easiest points of attack for erosion, so that it is a very common thing to find a stream flowing in a gorge, which marks the crest of an anticline, while synclinal basins are frequently left to form the summits of ridges, as is so markedly the case in the semi-bituminous coal basins of Pennsylvania. It is quite probable, however, that the anti- cline may have been leveled off at this fissured crest because it was upheaved under water and became exposed at its vulner- able summit to wave action. Ore deposits may collect in these fissured strips, of which tfafe lead and zinc mines of the upper Mississippi Valley (Example 24) are illustrations. Such fissures are peculiar in that they exhibit no displacement. The accompanying figure is from a photograph of a gaping crack in the Aubrey (Upper Carbonif- erous) limestone, twenty-five miles north of Canon Diablo sta- tion, Ariz., on the Atlantic and Pacific Railroad. It was caused by a low anticlinal roll and contained water about one hundred feet below the top. Its reproductions of the condi- tions of a vein, with horse, pinches and swells, devious course, and all, is striking. The photograph was made by Mr. G. K. Gilbert, of the United States Geological Survey, and to his courtesy its use is due. While it is true that in many regions the folds and fractures have resulted in this simple way, and exhibit tbe unmistaka- ble course through which they have passed, yet geological structure is by no means always so clear. Extended disturb- ances, great faults and displacements, combined with folds and the intrusion of igneous rocks, have often so broken up a dis- trict that it is a matter of much difficulty to trace out the coTirse through which it has passed. Subsequent erosion, or the superposition of heavy beds of gravel or forest growths, etc., may so obstruct observation even of the facts as to add to the obscurity. The expense of making and the consequent scarcity of accurate contour maps to assist in such work are other obstacles. The profound dynamic effects wrought by ON THE FORMATION OF CAVITIES IN BOOKS. 19 mountain-making processes, although in individual cases pro- ducing only the simpler phenomena already cited, yet in gen- eral are much more extensive, and must be considered in the study of many large districts. When folds are the result of compression or thrust, the dynamic effects are more marked than in those formed by sagging. Faults are larger and more abundant. When sedimentary beds have been laid down along an older axis of granite or some gqually resistant rock and the thrust crowds the beds against this/axis, the conditions are eminently favorable to great fracturing and disturbance. The flanks of the Rocky Mountains furnish such examples. 1.02.06. There are also great lines of weakness in the outer portion of the earth, which seem to have been the scene of faulting movements from a very early period. Thus, on the western front of the Wasatch Mountains, in Utah, is a great line of weakness, that was first faulted, as nearly as we can dis- cover, in Archean times, and has suffered disturbances even down to the present. A few instances of actual movements within recent years have been recorded. In 1889 a sudden small fold and fissure developed under a paper mill near Ap- pleton, Wis., and heaved the building four and a half inches. (See F. Cramer, "Recent Rock Flexure," Amer. Jour. Sci., III., xxxix. 220.) This occurred in what was regarded a set- tled region, and one not liable to disturbance. 1.02.07. Wherever igneous rocks form relatively large por- tions of the globe they necessarily share extensively in ter- restrial disturbances. Not being often in sufficiently thin sheets, they rarely furnish the phenomena of dip and strike. Folds are largely wanting. Thej' are replaced by faults and shattering. The fissures thus formed are at times of great size and indicate important movements. The Comstock Lode fis- sure is four miles long and in the central part exhibits A vertical displacement of three thousand feet. (See 2.11.21.) Such fissures seldom occur alone, but minor ones are found on each side and parallel with the main one. 1.02.08. The intrusion of igneous dikes may start earth- quake vibrations which fracture the firm rock masses. Fis- sures caused in this way radiate from the center of disturbance or else appear in concentric rings. The violent shakings which so often attend great volcanic eruptions, and the sinking of 30 KEMP'S ORE DEPOSITS. the surface from the removal of underlying molten material, all tend to form cracks and cavities. They are possible causes which may well be borne in mind in the study of an igneous district. 1.02.09. Faults. — When fractures have been formed by any of the means referred to above, and the opposite walls slip past each other, so as not to correspond exactly at all horizons, they are called "faults," a term which indicates this lack of correspondence. The separation is chiefly due to the relative slipping down or sinking of one side. The distance through which this has taken place is called the amount of displacement, or throw. Fig. 3. — Normal fault, Leadville, Colo. After A. A. Blow. Trans. Amer. Inst. Min. Eng., XVIII. , 180. Plate TV. Faults are most commonly inclined to the horizon, so that there is bolh a vertical and a horizontal displacement. The in- clination of a fault plane to the horizontal is called the dip, just as in the case of stratified rocks. Its inclination to the vertical is the hade. Faults most commonly run parallel with the strike of inclined rocks, and are then called "strike- faults." When they cut across the strike and are ih the direction of the dip they are called "dip- faults." Experience has shown that FiQ. 3. — Open fissure in the Aubrey limestone {Upper Carboniferous) miles north of Canon Diablo Station, Ariz., on the A. & P. R. R. Reproduced from a photograph by O. K. Gilbert, 1893. (Science, Augusts, 1895, 118.) ON THE FORMATION OF CAVITIES IN BOGKB. 21 where beds or veins encounter faults and operations aro brought to a standstill, the continuation is usually found as follows, according to Schmidt's law. If the fault dips or hades away from the workings, the continuation is down the hade; if it dips toward tbe workings, it should be followed upward. Such a fault is called a normal, or gravity fault, and is illustrated in the figure on p. 20, after A. A Blow. This is a natural result of thp drawing apart of the tAvo sides. The least supported mass would slip down ou the one which has the larger base. Less commonly the opposite movement results. Thus, when the fault is due to compression, the beds pass each other in the reverse direction, and what is called a reverse fault results. The accompanying cut illustrates a very extended one in the Cohattw Conijlomevati Ocoee Slate Knox Dolomite ?^-^»s^ Connasauga Shales FlQt. 4. Reversed Fault at Holly Creek, near Dalton, Oa. Hayes, Bull. G. S. A., Vol. II., PI. 3, p. 163 After C. W. southern Appalachians. While we would naturally think of a reversed fault as resulting from a compressive strain, in that in this case the lower wedge-shaped portion would be forced under the upper one, yet normal faults can likewise, in in- stances, be explained by compression. If we consider the fault to be caused by the vertical thrust or component, that would al- ways be present in the compression of a completely supported arch, this would tend to heave upward the portion next the fissure that had the larger base. Along an inclined fracture such portion is manifestly the under oue. Again, if the com- pressive strain is applied in a direction parallel with the fissure, and not at right angles to it, the hanging wall might be forced to bulge downward and the footwall upward, thus 22 KEMP'S ORE DEPOSITS. yielding a normal fault by compression. It is important to note whether the fault plane, both in normal and in reversed faults, cuts inclined beds in the direction of the dip or across it, because the relative amount of vertical and lateral displace- ment is much affected by these considerations. (See Margerie and Heim, Dislokation der Erdrinde, Zurich, 1888.) 1.02.10. The movement of the walls on each other produces grooves and polished surfaces called slickensides, or slips. They are usually covered with a layer of serpentine, talc, or some such secondary product. The strain caused by the move- ment may in rare instances leave the slips in such a state of tension that when, from any cause, such as excavation, the pressure is relieved, they will scale off with a small explosion.' Observations on the directions of slips may, in cases of doubt, throw some additional light on the direction of the movement which occasioned the fault. Some particular and recognizable bed or vein may be crushed and dragged down by the faulting movement, and afford the so-called "trail of the fault," which will indicate the direction of movement and direct the miner. But the best guide in stratified rocks is a knowledge of the suc- cession of the beds as revealed by drill cores or excavations. Attempts have been made to deduce mathematical formulas for the calculation of the amount of downthrow or upthrow, and when sufficient data are available, as is often the case in coal seams, this may be done. The methods depend on the projection of the planes in a. drawing, on the principles of ana- lytical geometry, and on the calculation of the displacements by means of spherical trigonometry.^ Prof. Hans Hoefer has called attention to the fact that in faulting there is frequently a greater displacement in one por):ion of the fissure than in a neighboring part, and even a difference of hade. This causes a twisting, or circular movement of one wall on the other, and 1 See A. Strahan, "On Explosive Slickensides," Geological Magazine, IV. 401, 533. 2 See G. Koehler, Die Stdningen der Crunge, Flotze und Lager, Leipzig, 1886 ; William Englemann. A translation by W; B. Phillips, entitled, "Ir- regularities of Lodes, Veins and Beds," appeared in the Engineering and Mining Journal, June 35, 1887, p. 454, and July 3, 1887, p. 4. A very ex- cellent paper, having a quite complete bibliography, is F. T. Freeland's "Fault Rules," Trans. Amer. Inst. Min. Eng., XXI. 491, 1893. UN THE FORMATION OP CAriTIES IN ROCKS. 23 needs to be allowed for in some calculations/ In the Engineer- ing and Mining Journal for April and May, 1892, a quite extended discussion of faults by several prominent American mining engineers and geologists is given, apropros of the ques- tion raised by Mr. J. A. Church as to whether fissure veins are more regular on the dip or on the strike. In a relatively uniform massive rock the regularity should be greater on the dip, but in inclined and diversified stratified rocks too many variables enter to warrant any sweeping assertions. In soft rocks like shales the fissure may become so split into small stringers as to be valueless. Again, in very firm rock, where there is little drawing apart, the fissure may be very tight. Fia. 5. Illustration of an older vein, the Jumbo, faulted by a later one, (cross-vein) at Newman Hill, near Rico, Colo. After T. A. Rickurd, Trans. Amer. Inst. Min. Eng., XXVI., 951. In the veins of Newman Hill, near Rico, Colo, (see 2.09.11), the fissure is so narrow above a certain statum as practically to fail. Quartzite is a favorable rock for such efiiect. Despite all rules, faults are often causes of great uncertainty, annoy- ance, and expensive exploration. 1.02.11. -If a number of faults succeed one another in a short distance, they are called "step faults." An older and completed vein may also be faulted by one formed and filled later. In such a case the continuous one is the younger. Figure 5 above will illustrate each case. At the intersection of the two, the later vein is often richer than in other parts. 1.03.13. If a faulted series of rocks is afterward tilted and eroded, so as to expose a horizontal section across the strike of the faulting plane, an apparent horizontal fault may result; or ' Oesterreiohes Zeitsehrift fiXr Berg- und HiXttenwesen. Vol. XXIX. An abstract in English is given by E. W. Raymond, Trans. Amer. Inst. Min. Eng., X. 456, 1883. 24 KEMP'S ORE DEPOSITS. if the erosion succeeds normal faulting and lays bare two un- conformable beds each side of the fissure, a lack of correspond- ence in plan as well as in section may be seen. Faulting frac- tures are seldom straight; on the contrary, thej' bend and cor- rugate. When the walls slip past each other, they often stop with projection opposite projection, and depression opposite depression. These irregularities cause pinches and swells in the resulting cavity, and constitute one of the commonest phe- nomena of veins. Fissures also gradually pinch out at their extremities, or break up into various ramifications that finally entirely cease. They may pass into folds, as stated above. It is not surprising, therefore, that in stratified rocks, the largest faults; as a matter of observation, are usually parallel with the general strike. They cross the strike or run in the sense of the dip much less frequently. 1.02.13. Zones of Possible Fracture in the Earth's Crust. — In a discussion of the deformation of rocks C. R. Van Hise^ has recently established the conception of three zones in the earth's crust, which are intimately connected in a large way with the subjects just discussed. They are (1) an upper zone of fracture; (2) a middle zone of combined fracture and plas- ticity; (3) a lower zone of plasticity. (IX Rocks under less weight than their ultimate strength, when rapidly deformed, are in the zone of fracture. This is manifestly incontroverti- ble and the conception adds to the points touched on in preced- ing paragraphs the important further one of the load under which the rocks stand at the time of experiencing the strain. As alreadj' pointed out, the character of the wall rock will influence the resulting fissure, firm rocks giving clean-cut fissures, while soft rocks, such as shales, will more readily break along multitudes of small cracks. The amount of load is also important, for with its increase even the firmest rock could not fracture, as is shown in describing the next two zones. It is also manifest that the depths of the zones are vari- able in different regions, on account of local differences of rocks, and that they are not to be too sharply viewed in a quan- titative way. ' Principles of North American Pre-Cambrian Geology, XVI. Annual Rep Dir U. S Geol. Survey, Part I , 589, 1896. See also Journal of Geology. IV. 195, 312, 449, 593. ON THE FORMATION OF GAriTIES IN ROOKS. 25 In round numbers the maxirmim depths at which cavities can exist varies from 600 meters (1,625 ft.) for soft shales to 10,000 meters (32,500 ft.) for firm granites. These maximum depths introduce zone (3), or the zone of fiowage, wherein the load is so excessive that the yielding to deformation comes in the way of a viscous flow, or plastic yielding, evidences of which are visible in many gneisses. That such a zone exists will appear to any one who reflects upon the necessary behavior and yield- ing of rocks, which are confined on all sides and yet are com- pressed beyond their limits of resistance. The second or inter- mediate zone embraces the border region between (1) and (3), or the region of combined fracture and flowage. These considerations have an important bearing on the forma- tion of veins, because they indicate that veins must be limited to the outer portions of the globe and must have always formed in such surroundings. The considerations as regards their practical bearing are largely theoretical, it must be admitted, because even moderate estimates of the depth of zone (1) soon reach below the limit of possible mining,' but in their broad scientific bearings they are a valuable aid to the formation of correct views on the necessary place of origin of veins. The "ewige Teufe" of the earlier miners is therefore quite limited. 1. 02. 14. Secondary Modifications of Cavities. — Fractures and cavities of all sorts speedily become lines of subterranean drainage. The dissolving power of water, and to a much smaller degree its eroding power, serve to modify the walls very greatly. An enlargement may result, and what was per- haps a small joint or fissure may become a waterway of con- siderable size. This is especially true in limestones, in which great caverns (like the Mammoth Cave and Luray's Cave) are excavated. Caves are, however, almost always due to surface water, and do not extend below the permanent water level un- less they have been depressed after their formation.^ 1.02.15. The subterranean movements of water are of prime importance in connection with so many aspects of the subject of ore deposits that it is necessary to have a fairly definite con- ' See in this connection A. C. Lane, "How Deep Can we Mine?" The Mineral Industry, IV. 767. 10,000 ft. is placed as a general limit, with possibilities as far as 15,000, but probably not much beyond, '' See J. S. Curtis, Monograph VII. , U. S. Oeol. Survey, Chap, VIII, 26 KEMP'S ORE DEPOSITS. ception of their nature and causes. Water falling on the sur- face as rain in part runs off at once, in part evaporates, at least before it has gone far, and in part sinks into the ground. With the last named we are especially concerned. World-wide experience long ago demonstrated that under all portions of the land, unless possibly in excessively arid and exceptional districts, there is a body of almost stationary water, that main- tains a very constant level and that will fill a well if one is sunk sufficiently deep. Where the rainfall is heavy this "per- manent water level" or "ground water" stands only a short distance below the surface, it may be only a few feet ; but in regions of slight rainfall, it is correspondingly depressed. It varies also, more or less, with the nature of the local rocks, with the nearness or remoteness of low-lying valleys and with the geological structure.^ The "ground water" that stands at this level is to be distinguished from the actively circulating water above it— the "vadose" circulation of Posepny,^ whose recent treatise has served to focus attention upon this phase of the subject — and is not itself without motion, because where it is situated above some more or less remote and lower lying outlet it passes toward it by a slow, gradual flow, or sinks downward, moves laterally and rises again by a siphonic ac- tion. Cracks and clefts are the chief lines of movement in both these circulations, and instances are known of communi- cations across wide intervals. Capillary circulations are also not lacking but are of less quantitative moment. As solvents of rocks the ground-water circulations are not comparable with the vadose, for, as already remarked, caves, the chief results of such solution and removal, are essentially products of the latter. 1.02. 16. The ground-water stands between the motive power of the overlying hydrostatic column and the further motive power of the underlying heated zones of the earth, to which some of the surface water attains, more or less by capillary movements. Daubree has shown that capillary attraction is ' See, in this connection, T. C. Chamberlin, ' ' The Requisite and QuaUf y- ing Conditions of Artesian Wells," Fifth Annual Rep. Dir. U. S. Geol. Survey, 131, 1885. ^Transactions Amer. Inst. Min. Eng., XXIII. 313, 1893. Reissued as " Genesis of Ore Deposits," in which see p. 17. ON THE FORMATION OF CAVITIES IN ROCKS. 37 effective even against steam pressure.' Cooling but still heated intrusions of igneous rocks, vyhich may not necessarily reach the surface, are doubtless the most serious of all these internal stimulators, and furnish us with the most reasonable cause for those active circulations, that have led to ore-deposi- tion in regions of extended mineral veins. They are at once localized, of relatively abrupt development, and they bring great stores of heat within the conceivable zones of the ground- water's existence. It is also quite probable that waters and other fluid or vaporous substances are emitted and driven out- ward, which are not derived from infiltrations from the surface, but which have been involved in the substance of igneous mag- mas since their derivation from the original nebula. All these circulations from deep-seated sources are more likely to be fillers than enlargers of cavities in the upper portions of the zone of fracture. It is conceivable that the heat necessarily developed in the crushing and fracture of rocks on a large scale may also be an important local stimulus and in this way contribute in no small degree to the final results. 1.02.17. The solvent action of water is vastly augmented by the carbonic acid which it gathers from the atmosphere, and this is the chief cause of the excavations wrought by it in lime- stones. Pure cold water has comparatively small dissolving and almost no eroding power. It has also been advocated that various acids which result from the deca}'' of vegetable matter aid in such results.^ This may be true, but in general carbonic acid is the chief agent. Iron in minerals falls an easj^ prey, as does calcium, and both are dissolved out in large amount. (See Example 1.) When charged with alkaline carbonates, water has the power to attack other less soluble minerals, such as quartz and silicates, and by such action the walls of a cavity in the crystalline rocks may be much affected. ' The most important works bearing on this entire question of under- ground waters are those of Daubree, viz. : "Etudes Synthetiques de Geologie Experimental e," 1879. "Les Eaux Souterraines aux Epoques anciennes," 1887, "Les Eaux Souterraines a I'Epoque actuelle," 1887, 2 vols. Suggestive reading will also be found in C. E. Van Hise, ' ' Metamorph- ism of Rocks and Rock-flowage, Bull. Qeol. Soc. Amer. , IX. 269. ' A. A. Julien, Amer. Asso. Adv. Sci, 1879, p. 311. 28 KEMP'8 ORE DEPOSITS. 1.02.18. As has been set forth in a previous paragraph, waters percolating to great depths in the earth, or circulating in re- gions of igneous disturbances, become highly heated, and this too at great pressure. Under such circumstances the solvent action is verj' strongly increased, and all the elements present in the rock-making minerals are taken into solution. Alka- line carbonates are formed in quantity; silica is easily dis- solved; alkaline sulphides result in less amount; and even the heaviest and least tractable metals enter into solution, either in the heated waters themselves, or in the alkaline liquors formed by them. The action on the walls of cavities and courses of drainage is thus profound, and accounts for the fre- quent decomposed character of the walls and the general lack of sharpness in their definition. The vast amount of siliceous material deposited by hot springs and gej'sers is additional evi- dence of its importance. When the uprising solutions reach the regions of diminished temperature and pressure they con- __ tribute their burden of dissolved minerals to veins and surface accumulations. 1.02.19. The composition of mineral springs is of the great- est interest in this connection, and is a subject that has received much attention in recent years.^ The vast majority of those recorded contain chiefly silica and salts of alkalies and alkaline earths, of which a few represent the gangue minerals. Here and there, however, examples with metallic contents have been detected, and in several instances springs have been met in deep mines and the waters have been analj'zed. Often the ore deposition, as indicated by these, seems to have ceased, but again either in the waters themselves or in crusts formed by them, metallic minerals have been detected. In the table be- low the first seven relate to American cases, the last three to ' R. N. Brackett, " Mineral Waters of Arkansas," Oeological Survey of Arkansas, 1891, I. Gooch and Whitfield, "Analyses of Waters of the Yellowstone National Park,'' Bulletin 47, U. S. Geol. Survey. A. C. Peale, ' ' Lists and Analyses of the Mineral Springs of the United States, Bulletin 32, Idem. F. Posepny, "Genesis of Ore Deposits," pp. 36-48. J. Roth, " Allgemeine und Chemische Geologie," I. Chap, x., 407. P. Schweitzer, "The Mineral Springs of Missouri," Mo. Geol. Survey, m. 1892. ON THE FORMATION OF CA VITIES IN BOOKS. 29 European. All the amounts are expressed in parts per mil- lion, i. e., grams per 1,000 liters. 1.02.20. In analyses I. and II. metallic salts were not them- selves detected, but ammonium carbonate was, and on its presence, as well as the results of experiment, Becker bases his explanation of the introduction of the cinnabar. Cinnabar is found to be soluble in ammoniacal liquors under pressure and heat, but to precipitate again as the pressure and temperature fall. The water from Steamboat Springs did yield traces of quicksilver, but the crusts which had been precipitated at the surface of the ground in past time afforded in this order : sul- phides of arsenic and antimony, ferric hydrate, lead sulphide, copper sulphide, mercuric sulphide, gold and silver, and traces of zinc, manganese, nickel and cobalt.^ The waters from the Geyser mine were of exceptional interest. When compared with each other it is noticeable that the vadose waters (IV.) have much less metallic matter than the deep-water (V.), and that in the latter the metals appear in much the same relative abundance as in the ore (VI. and VII.). In the "Genesis of Ore Deposits," from which analyses VIII., IX. and X. have been taken, Posepny has collected many more, and cites some in- stances abroad in which the metals have also been noted. An- timony, arsenic, bismuth, iron, manganese, copper, tin, cobalt, nickel, lead, zinc and uranium are to be numbered among them. So far as the metals are concerned all the analyses in- dicate extremely dilute solutions, and the waters must, have required a ver}' long period of time to yield the ore bodies. The dissolved content of alkaline salts must have flowed away on the surface and have disappeared. I. Water from the Hermann shaft at Sulphur Bank, Califor- nia, from a quicksilver mine. Monograph XIII., U. 8. Geol. Survey, p. 259. W. H. Melville, Analyst. II. Parrott shaft, same locality. Idem. III. Steamboat Springs, Nev. Idem. p. 349. IV. Calculated composition of the vadose water at the 500- ft. level of the Geyser silvermine, Silver Cliff, Colo., in rhyo- lite tuff. The analysis is made up from analyses of the water and of the sediment that settled from it, chiefly by precipita- 1 Monograph XIIL, U. 8. Geol. Survey, 343. 30 KEMP'S ORE DEPOSITS. I. II. m. IV. V. SiOj 37.15 41.85 25.90 24.42 A1»0. 0.25 1.06 ALOo P»0..... 0.80 1.60 1.70 93.50 Feed;. . ?....; . ....... ..... . . . . . 0.98 0.29 7.25 MnCOs 1.19 CaCOq 36.20 23.40 50.65 15.77 366.03 CaS04 CaoPnOo 1.37 Trace. Trace. SrCO. 3.29 MgCOa 18.90 5.55 0.99 42.85 4.20 16.60 621.84 KjSOa ... 19.18 KCl... ■ 47.05 74.70 197.35 361.34 KBr, KI Trace. NajCOj 1,946.75 322.60 689.05 1,039.75 43.14 111.47 1,41 1.75 38.70 60.50 1,489.67 Na„SOi 223.53 1,102.70 NaNOa 2.19 1,8/8.40 2,404.35 818.68 390.90 290.23 8.58 8.66 1.00 56.50 Trace. Mcos^^* ■.'■".'.'.■.*.' ■'*■*.'.■ '.::::. NaHS NAftA<5S LioSOd LiCl 17.30 (NH.lnOOo 6.64 4.55 262.41 6.00 2.82 0.74 1,751.81 7.6 COa 37.80 1,418.61 HgS, nNajS Trace. Trace. Trace. 0.40 1.74 0.04 0.66 Gold Silver Lead Zinc Copper Iron Manganese Lime Sulphur.... Silica Total VI. vn. Trace. Trace. 1.05 1.27 23.80 17.60 14.00 11.10 1.50 2.30 2.30 2.00 1.20 0.80, 1.70 12.60 9.60 33.60 46.90 91.75 91.47 Alk. Carbonates Earthy Carbonates Alk. Sulphates Earthy Sulphates.. . Chlorides Silica Others vru. 352.00 55.00 12.00 6.00 61.00 IX. 1,160.00 610.00 82.00 2, SOT. 00 729.00 37.00 6.00 .58.00 72.00 6.00 tion inthecarboj'. XVII. Ann. Rep. Dir. U. S. Geol. Surv., Part II., p. 463. W. F. Hillebrand, Analyst. V. Calculated composition of deep waters, 3,000-ft. level, same place and conditions. Idem. VI., VII. Analyses of two carload lots of ore from same mine, made at Arkansas Valley smelter, Leadville. Idem, p. 457. The gangue was chiefly barite, calcite and chalcedony. VIII. Water from the Einigkeit's shaft, Joachimsthal, Bo- hemia, presumably at a depth of 533 meters (1,774 ft.), as stated on p. 27 of citation. Analysis on p. 38, " Geflesis of Ore Deposits. " ■ON THE FORMATION OF CAVITIES IN ROCKS. 31 Analyst, J. Seifert. The table of equivalent temperatures on p. 37 of original is incorrect. IX. Gottesgeschick naine, Schwarzenberg, Saxony. Idem. Analyst, R. Richter. X. "Sprudel" spring in a colliery at Brux, Bohemia. Idem. Analyst, J. Gintl. 1.02. -JO. Magnesia is one of the alkaline earths readily taken into solution by carbonated waters, and when such wa- ters again meet' limestone the effect is often very great, and constitutes one of the most important methods of the formation of cavities. Solutions of magnesium carbonate, on meeting calcium carbonate, effect a partial exchange of the former for the latter. This leaves the rock a double carbonate of calcium and magnesium, which is the composition of the mineral and rock dolomite. The process is therefore called dolomitization. (See Example 25. ) It may bring about a general shrinkage of eleven or twelve per cent. In any extended thickness of strata this would cause vast shattering and porosity. As an illus- tration of its results, the following analysis of normal, un- changed Trenton limestone of Ohio, and of well drillings from the porous, gas-bearing, dolomitized portions of the same, are given. They are taken from a paper by Edward Orton. {Ame7\ Manuf. and Iron World, Pittsburg, Dec. 3, 1887.) CaCOs. MgCOs. Fe,03,AU03. SiO^. Unchanged Trenton limestone. .79.30 0.92 7.00 12.00 ..82.36 1.67 0.58 12.34 Dolomitized " " ..53.50 43.50 1.25 1.70 " ..51.78 36.80 1.02.21. Recent studies in ore deposits by Posepny, Curtis and Emmons indicate also that solutions of metallic ores may affect an interchange of their contents with the carbonate of calcium or magnesium in limestones and dolomities, leaving an ore body in place of the rocks. This change is effected molecule by molecule, and is spoken of as a metasomatic inter- change or replacement. (See Example 30.) By "metasoma- tic" is meant an interchange of substance without, as in pseu- domorphs, an imitation of form. Alteration of the metallic ores may follow and occasion cavities from shrinkage. (See Example 36, and Curtis, on Eureka, Nev., Monograph VIII. U. S. Geol. Survey, Chap. VIII.) CHAPTER III. THE MINERALS IMPORTANT AS ORES; THE GANGUE MINER- ALS, AND THE SOURCES WHENCE BOTH ARE DERIVED. 1.03.01. The minerals which form the sources of the metals are almost without exception included in the following com- pounds: the sulphides and tellurides, the arsenides and antimo- nides, the oxides and oxidized compounds such as hydrous oxides, carbonates, sulphates, phosphates, and silicates, and one or two compounds of chlorine. A few metals occur in the native state. All the other mineral compounds such as a chromateor two, a bromide or iodide, etc., are rarities. It may- be said that nine-tenths of the productive ores are sulphides, oxides, hydroxides, carbonates, and ■ native metals. The ores of each metal are subsequently outlined before its particular deposits are described. 1.03.02. The most common gangue mineral is quartz, while in less amount are found calcite, siderite, barite, fluorite, and in places feldspar, pyroxene, hornblende, rhodonite, etc. The silicates are chiefly present where the gangue is a rock and the ore is disseminated through it. All the common rocks serve in this capacity in one place or another. 1.03.03. Source of the Metals. — The metallic contents of the minerals which constitute ores must logically be referred to a source, either in the igneous rocks, or in the ocean. If the nebular hypothesis expresses the truth — and it is the best formulation that we have — all rocks, igneous, sedimentary, and metamorphic, must be traced back to the original nebula. This, in cooling, afforded a fused magma, which chilled and assumed a structure analogous to the igneous rocks with which we are familiar. Igneous rocks must thus necessarily be con- sidered to have furnished by their erosion and degradation the materials of the sedimentary rocks; while igneous and sedi- THE MINERALS IMPORTANT AS ORES, ETC. 33 raentary alike have afforded the substances whose alterations have produced the metamorphic rocks. It may also be true that eruptive rocks, especially when basic, have Ipeen formed, by the oxidation and combination with silica, of inner metallic portions of the earth, for this is one of our most reasonable explanations of volcanic phenomena, suggested alike by the composition of basalts, by the high average specific gravity of the globe, and by analogy with meteorites. 1.03.04. As opposed to this conception, there are those who would derive the metallic elements of ores from the ocean, in which they have been dissolved from its earliest condensation. Thus it is said that substantially all the metals are in solution in sea water. From the sea they are separated by organic creatures, it may be, through sulphurous precipitation, attend- ant on the decay of dead bodies. The accumulations of the remains of organisms bring the metals into the sedimen- tary strata. Once thus entombed, circulation may concentrate them in cavities. When present in igneous rocks, the latter are regarded as derived from fused sediments. If the metallic contents of sedimentary rocks do not come from' the ocean in this way, the igneous rocks as outlined above are the only pos- sible source. No special mention is here made of the meta- morphic rocks, because in their original state they are rtifera- ble to one or the other of the two remaining classes. But it is not justifiable in the absence of special proof to consider them altered sediments, any more than altered igneous rocks, and it is doubtless true that the too generally and easily admitted sedimentary origin for our gneisses and schists has materially hindered the advance of our knowledge of them in the last forty years. 1.03.05. Microscopic study of the igneous rocks has shown that, with few exceptions, the rock-making minerals separate from a fused magma on cooling and crystallizing, in a quite definite order.^ Thus the first to form are certain oxides, mag- netite, specular hematite, ilmenite, rarely chromite and pico- tite, a few silicates, unimportant in this connection (zircon, titanite), and the sulphides pyrite and pyrrhotite. Next after these metallic oxides, etc., the heavy, dark-colored, basic sili- ' H. Rosenbusch, "Ueber das Wesen der koernigen und porphyrischen Structur bei Massengesteine, " Neues Jahrhuch, 1883, ii,, 1, 34 KEMP'S ORE DEPOSITS. cates, olivine, biotite, augite, and hornblende are formed. All these minerals are characterized by high percentages of iron, magnesium, calcium, and aluminum. They are very gener- ally provided with inclusions of the first set. Following the bisilicates in the order of crystallization, come the feldspars, and after these the residual silica, which remains uncombined, separates as quartz. 1.03.06. If we regard the igneous rocks as the source, the metallic elements are thus to be ascribed to the first and sec- ond series of crystallizations, while the elements of the gangue minerals are derived from the last three. It is a doubtful point whether the less common metals, such as copper, silver and nickel, enter into the composition of the dark silicates as bases, replacing the iron, alumina, lime, etc., or whether they are present in them purely as inclusions of the first series. F. Sandberger^ argues in support of the first view, but his critics, notably A. W. Stelzner, cast doubt upon his conclusions on the ground that his chemical methods were indecisive. The case is briefly this: Sandberger, as an advocate of views which will be subsequently outlined, separated the dark silicates of a great many rocks. By operating on' quantities of thirty grams he proved the presence in them of lead, copper, tin, antimony, arsenic, nickel, cobalt, bismuth, and silver, and considered these metals to act as bases. The weak point of the demonstra- tion consists in dissolving out from the powdered silicate, any possible inclusions. There seems to be no available solvent which will take the inclusions and be without effect on the silicates. This is the point attacked by the critics, and appa- rently with reason. It is, however, important to have shown the presence of these metals, even though their exact relations be thus doubtful. Quite recently in a series of "Notes on Chil- ean Ore Deposits." Dr. Moricke^ mentions native gold in pearlstone (obsidian) from Guanaco, in skeleton crystals in the ' The principal paper of Professor Sandberger is his "XJntersuchungen fiber Erzgange," 1882, abstracted in the Engineering mid Mining Journal, March 15, 22, and 29, 1884; but a long series of others might be cited in which the investigations, notably at Pribram, Bohemia, are in- terpreted as indicated above A. W. Stelzner, B. and H. Zeit., xxxix., No. 3, Zeitsch. d. d. g. Gesell.xxxi. 644. "Die Lateral-secretions-Theorie, etc." Reprint Freiberg, 1889. ° Tsonermaks Min. and Petrog. Mitth., XII., p. 195. THE MINERALS IMPORTANT AS ORES, ETC. 35 glass, as inclusions in perfectly fresh plagioclase and sanidine crystals, and in spberulites. G. P. Merrill has recorded gold as an original mineral in biotite-granite from Sonora, Mexico.' A. Simundi reported years ago the existence of gold in the gran- ites of Owyhee Co., Idaho, far from any vein, to an amount equal to 25 cents per ton.^ The existence of silver in quartz- porphyry has been demonstrated in this country by J. S. Curtis, at Eureka, Nev. f both the precious metals have been shown by G. F. Becker to be in the diabase near the Comstock Lode f and, by the same mvestigator, antimony, arsenic, lead and copper, were proved to be contained in the granite rear Steam- boat Springs, Nev.* S. F. Emmons has also shown that the porphyries at Leadville contain appreciable, though small, amounts of silver.* Of forty-two specimens tested, thirty-two afforded it; of seventeen tested for lead, fourteen yielded results. Emmons has also recorded determinations of silver by L. G. Eakins in the eruptive rocks of Custer Co., Colo., in connection with investigations upon the interesting ore-bodies of the dis- trict. Nine rocks were assayed, embracing trachytes, an ande- site-breccia, a different andesite, rhyolite, red granite, black granite, the separated bisilicates of the last-named, and diorite. Five out of the nine contained appreciable amounts, viz., one trachyte, the rhyolite. the diorite, and both granites. The amounts vary from 0.005 to 0.403 of an ounce per ton. The separated bisilicates yielded 0,045 per cent, lead and 0.04 of an ounce of silver.^ Undoubtedly the multiplication of tests will show similar metallic contents in other regions. Thus the augite of the eastern Triassic diabase will probably j'ield cop- per, for this metal is abundant in connection with the outflows. 1.03.07. Among the igneous rocks certain metals seem to be characteristically associated with some varieties, others again with a different series, while to many no generalizations apply. The basic rocks are the richest in iron, but the metal is not lacking in the most acidic. Copper in association with " G. P. Merrill, Gold in Granite, Amer. Jour. Scl, April 1896, 309, Si- mundi's results are given by G. F. Becker. — Tenth Census, XIII. 52. ■" Monograph VII. , U.S. Geol. Survey, p. 80. ^ Monograph III, U. S. Oeol. Survey. " Monograph XIII, U. S. Geol. Survey, p. 350. ^ Monograph XII., U. S. Oeol. Survey, p. 569. " XVII. AYlnual Rep. Director U. S. Oeol. Survey, Part II., 471. 36 KEMP'S ORE DEPOSITS. nickel and some cobalt is found in widely separated parts of the world in basic gabbros, but other cases are equally pro- nounced in which it seems connected with igneous rocks of medium acidity, or with sediments having no visible connec- tion with igneous rocks at all. The greatest copper district now productive, Butte, Mont., has only granites and rhyolites (quartz- porphyries) exposed for miles around. Lead and zinc are more commonly associated with limestones than with any other one rock, but the precipitating action of this rock, rather than any original content of the metals in it, is probably responsible for the association. In other respects no generalizations are possible. Gold and silver are cosmopolitan in their relations. The former has been found in the native state in igneous granite and perlite, and with pyrrhotite in basic gabbros, aside from its occurrence in veins. Silver in one locality and another is a companion of almost all types of rock ; chromium and plati- num are certainly at home in the basic peridotites and their serpentinous alteration products, and tin is seldom seen except in connection with granite. The other lesser metals that are of serious, practical importance admit of no general statements that are not largely speculative.^ The rarer elements do, however present some striking associations. The "rare earths" seldom if ever occur in notable amount except in pegmatites and gran- itic rocks. Vanadium finds its peculiar home in titaniferous mag- netite, but it is of remarkably wide distribution in basic rocks in general, as shown by over sixty analyses by Hillebrand and Stokes.^ The amounts are small, in only one case reaching a tenth of one per cent., and the vanadium favors the dark sili- cates, especially biotite. It has also been detected in surpris- ing quantities in the ashes of coals in Argentina and Peru.* ' These questions liave been discussed at length by L. De Lavmay, " Contribution a I'Etude des Gites Metalliferes," Annalesdes Mines, 'XU.., 1897, 119-328. J. H. L. Vogt, "Ueber die relative Verbreitung der Elemente, besonders der Schwermetalle und ueber die Concentration des ursprtinglich fein vertheilten Metallgehaltes zu Erzlagerstatten. Zeitsch. fur prakiiscJie Oeologie, August, 1898, to January, 1899. '' W. F. Hillebrand. "Distribution and Quantitative Occurrence of Vana- dium and Molybdenum in Rocks of the United States,'' .A)?ie)\ Jour. Sci. September, 1898, 209. ' W. P. Blake. Engineering and Mining Journal, Aug. 11, 1894, p. 128. Vanadium has been detected by R. S. McCaflEery, E. M., In coals used at Casapaloa, Peru. THE MINERALS IMPORTANT AS ORES, ETC. 37 Molybdenum is much rarer and appears to be limited to the acidic rocks. The mineral molybdenite is seldom met except in pegmatites. Tungsten has practically the same associa- tions as tin. 1.03.08. That the metals are so generally combined with sulphur in, ore deposits seems to be due to the extended distri- bution of this element, and to its vigorous precipitating action on nearly all the metals at the temperatures and pressures which prevail near the earth's surface. Sulphur is widespread in • pyrrhotite and pyrite, original minerals in many igneous rocks, and ones much subject to alteration; while sulphuretted hydrogen is common in waters from sedimentary rocks, and is a very general result of organic decomposition. Natural gas and petroleum from limestrne receptacles almost always con- tain it.' Many sulphides, too, are soluble under the pressures and temperatures prevailing at great depths, but are deposited spontaneously at the pressures and temperatures prevailing at or near the surface. 1.03.09. Where veins occur in igneous rocks the bases for gangue minerals have been obtained from the rock-making silicates. Calcium is afforded by nearly all the important ones; silicon is everywhere present ; barium has been proved in many feldspars, in small amount; and magnesia is present in many pyroxenes and amphiboles. Of the sedimentary rocks, limestone of course affords unlimited calcium, and recently Sandberger reports thathehas identified microscopic crystals of barite in the insoluble residues of one.'^ This is of interest, as barite is such a common gangue in limestone. 1.03.10. It may be remarked that the natural formation of both ore and gangue minerals has doubtless proceeded in na- ture with great slowness, and from very dilute solutions. Both classes exhibit a tendency to concentrate in cavities, even from a widely dispersed condition through great masses of compara- tively barren rock. The formation may have proceeded when the walls were far below their present position with regard to ' See, in this connection, J. F.Kemp, "Tlie Precipitation of Metallic Sulphideshy'Na.turaXQa.s," Engineering and3Iining Jovnial, Dec. 13, 1890. ^ Sitzimgsberichte rJ. Math. phys. Classe d. k. hayr, Akad. d. 'Wiss., 1891, xxi. 291. See also, W, F. Hillebrand, "The Widespread Occurrence of Barium and Strontium, in Silicate Eocks." — Jour. Amer, Chem. Soc, February, 1894, p. 81. 38 KEMP'S ORE DEPOSITS. the surface, so that to those inclined a wide latitude for specu- lation on origin is afforded. It is possible that in the earlier history of the globe circulations were more active than they are now— a line of argument on which a conservative writer would hesitate to enlarge. 1.03.11. In the above discussion of the sources of the ores and gangue, the vein-filling has been considered as primarily derived from the barren wall rock or from deep-seated sources, and as precipitated in its present position in the first concen- tration. Yet in instances it is by no means improbable that vein-fillings as found to-day are the product of several concen- trations, and that a deposit sufficiently rich to work may be the result of two, or more migrations since the first depar- ture from an originally sparsely disseminated condition in the mother rock. L. De Launay has elaborated this view in the paper cited above.' In a later paragraph of this book, 1.05.06, the secondary alterations of those portions of veins that lie in the region of the vadose circulation is taken up, but M. De Launay carries the idea much further in suggesting that in many veins the present filling may be due to the concentration of ore from much more of the vein than now appears above the rich places. It is certainly true, that, if a vein were formed several geological periods back, it would have shared in all the elevations and depressions to which its region had been subjected and consequently to considerable changes in the relations of the ground water and the vadose circulations. An explanation would also be afforded of the richness of some veins that has been marked within limited distances of the surface and that has decreased in depth. W. H. Weed has noted cases of this character in Montana that ere not as yet (1899) described in print. ' The full title of M. De Launay's paper is : I. Sur 1' importance des gites d' inclusion et de segregation dans une classification des gites metal- liferes. II. Sur le role des phenomenes d'alteration superficielle et de remise en mouvement dans la constitution de ces gisements. This may be freely translated. I. On the importance of magmatic inclusions and segregations in a classification of ore deposits. II. On the part played by phenomena of superficial alteration and of the renewal of migration in the constitution of these deposits. CHAPTEE IV. ON THE FILLING OF MINERAL VEINS. 1.04.01. Bearing in mind what precedes, the preliminaries for the discussion of mineral veins are set in order. We have traced the formation of cavities by the shrinkage of rock masses in cooling or drying, by the movements and disturbances of the earth's crust (which are far the commonest and most im- portant causes), and by dolomitization. The enlargement of such cavities by subterranean circulations followed, and the general effect of waters, cold and heated. The sources of the elements of the useful minerals were pointed out so far as known. All these general and indisputable truths assist in the drawing of right conclusions. It should be emphasized, as will appear later, that mineral veins or cavity fillings do not embrace all metalliferous deposits. On the contrary, the de- posits which either form beds by themselves, or which are dis- seminated through beds of barren rock and are of the same age with them, do not enter into the discussion. They are charac- terized by being younger than their foot walls, and older than the hanging. Their geological structure is far simpler, and, as will appear in the discussion of particular examples, the working out of their origin does not so often carry the investi- gator into the realms of speculation and hypothesis. And yet it is not to be inferred from the prominence here given to the discussion of veins that bedded deposits yield to them, in any degree, in importance. Iron ores, for instance, are often in beds. 1.04.02. Methods of Filling — Methods of filling were summed up a very long time ago by Von Herder and Von Gotta,' as follows: 1. Contemporaneous formation. 2. Lateral ' Erzlagerstdtten. 2d ed., 1839, Vol., I., p. 173. A later tabulation is given by G. F. Becker In Monograph XIII, U. 8. Geological Survey, pp. 444, 445. 40 KEMP'8 ORE DEPOSITS. secretion. 3. Descension. 4. Ascension b}' (a) infiltration, or (h) sublimation with steam, or (c) by sublimation as gas, or (d) by igneous injection. To these should be added the more recent theory of (5) replacement, which, however, is rather a method of precipitation than of derivation. No one longer be- lieves in contemporaneous formation, and descension has an extremely limited, if, indeed, any application. Ascension by sublimation as gas or with steam, or by igneous injection, has very few good applications. The discussion is practically re- duced to lateral secretion and to ascension by infiltration. 1.04.03. Lateral Secretion. — By lateral secretion is under- stood the derivation of the contents of a vein from the wall rock. The wall rock may vary in character along the strike and in depth. Three interpretations may be made, two of which approach a common middle ground with ascension by infiltration. It may first be supposed that the vein has been filled by the waters near the surface which are known to be soaking through all bodies of rock, even where no marked waterway exists, and which seep from the walls of any opening that may be'afforded. Being at or within comparatively short distances of the surface, the waters are not especially heated. As they emerge to the oxidizing and evaporating influence of the air in the cavity, their burden of minerals is deposited as layers on the walls. The second interpretation supposes the walls to be placed during the time of the filling at considera- ble depths below the surface, so that the percolating waters are brought within the regions of elevated temperature and pres- sure. Essentially the same action takes place as in the first case. The third interpretation increases the extent of the rock leached. Thus, if a mass of granite incloses a vein and ex- tends to vast depths, we may suppose the waters to come from considerable distances, and to derive their dissolved minerals from a great amount of rock of the same kind as the walls. Portions of this may even be in the regions of high tempera- ture, while the place of precipitation is nearer the surface. These last two interpretations have much in common with the theory of ascension by infiltration, and on this common middle ground lateral-secretionists and infiltration-ascensionists may be in harmony. 1.04.04. Ascension by Infiltration.— The theory of infil- ON TSE FILLING OF MINERAL VEINS. 41 tration by ascension in solution from below considers that ore- bearing solutions come from the heated zones of the earth, and that they rise through cavities, and at diminished temperatures and pressures deposit their burdens. No restriction is placed on the source from which the mineral matter has been derived. Indeed, beyond the fact that it is "below," and yet within the limits reached by waters, all of which have descended from the surface, and that the metals have been gathered up from a dis- seminated condition in rocks — igneous, sedimentary and meta- morphic— no more definite statement is possible. This theory is of necessity largely speculative, because the materials for its verification are beyond actual investigation. 1.04.05. In favor of lateral secretion the following argu- ments may be advanced. I. According to Sandberger, actual experience with the conduits, either natural or artificial, of mineral springs, shows that a deposit seldom, if ever, gathers in a moving current. It is only when sohitions come to rest on the surface and are exposed to oxidation and evaporation that precipitation ensues. Deposits in veins have therefore formed in standing waters, whose slight overflow or evapora- tion would be best compensated by the equally slight and grad- ual inflow from the walls. If in hot springs there were a strong and continuous flow from below, and discharge from above, the mineral matter would reach the surface.' Hence the deposit would be more likely to gather by the slow infiltrations from the wall rock, which would stand in cavities like the water of a well. We have, however, some striking instances of deposits in artificial conduits. Prof. H. S. Munroe has called the writer's attention to a case met by him in 1891. The fourteen-inch column pipe of a pump at the Indian Ridge Colliery, Shenandoah, Pa., which was raising ferruginous waters, became reduced in diameter to five inches within two years by the deposit of limonite. The same amount of water was forced through the five-inch hole as through the fourteen-inch. By figuring out the stroke and cylinder contents, it was found that in the clear pipe the water moved 162 feet per minute, aad in the contracted pipe 1,368 feet. And yet the deposit gathered. The conditions necessi- tated the continuous action of the pump, and it was not idle 1 Sajidberger, Untersuchungen ilber Erzgdnge, Heft I. 42 KEMP'S ORE DEPOSITS. over two hours in each two months of that period. The boiler feed-pipes of steamers plying on the Great Lakes also become coated with salts of lime. Years ago a disastrous boiler ex- plosion occurred from the virtual stoppage of the feed, by this precipitation. 1. 04.06. II. If a vein were opened up, in mining, which ran through two different kinds of rock, and if in the one rock one kind of ore and gaugue minerals were found, and in the other a different set, the wall rock would clearly have some influence. Thus in a mine at Schapbach, in the Black Forest, investigated by Sandberger, a vein ran through granite and gneiss. The mica of the granite contained arsenic, copper, co- balt, bismuth and silver, but no lead. The principal ore in this portion was tetrahedrite. The mica of the gneiss con- tained lead, copper, cobalt, and bismuth, and the vein held galena, chalcopyrite, and a rare mineral, schapbachite, contain- ing bismuth and silver, but probably a mixture of several sul- phides. No two ores were common to both parts of the vein. Another well-established foreign illustration is at Klausen, in the Austrian Tyrol. Lead, silver, and zinc occurred in the veins where they cut diorite and slates, but copper where mica schist and felsite formed the walls. In America there are' a number of similar cases. At the famous Silver Islet mine^ on Lake Superior the vein runs through unaltered flags and shales, and then crosses and faults a large diorite dike. Where the diorite forms 'the walls, the vein carries native silver and sulphides of lead, nickel, zinc, etc., but where the flags torm the walls the vein contains only barren calcite. Along the edges of the estuary Triassic sandstones of the Atlantic bordei, where they adjoin Archean gneiss, a number of veins are found which yield lead minerals, while in the sandstones near the well-known diabase sheets and dikes are others carrying copper ores. It was early remarked by J. D. Whitney that the ' W. M. Courtis, " On Silver Islet, " Engineering and Mining Journal, Dec. 31, 1878. Trans. Amer. Inst. Min. Eng., V. 474. E. D. Ingall, Oeol. Survey of Canada, 1887-88, p. 37, H. F. A. Lowe, "The Silver Islet Mine," etc., Engineering and Mining Journal, Dec. 16, 1882, p. 321. T, MacFarlane, "Silver Islet," Trans. Amer., Inst. Min. Eng., VIII, 336. Canadian Naturalist, IV, 38, McDermott, Engineering and Mining Journal, January, 1877, ON TUB FILLING OF MINERAL VEINS. 43 . lead was usually associated with the gneis=, "ihe copper with the diabase. 1.04.07. From instances like these it is inferred that the ores were derived each from its own walls, and by just such a leaching action by cold surface waters as is outlined above. As opposed to this, it has usually been claimed that each par- ticular wall exerted a peculiar selective and precipitating ac- tion on the metals found adjacent to it and none on the others, so that if a solution arose carrying both sets, each came down in its particular surroundings while the others escaped. Dr. W. P. Jenney has called the writer's attention to such a case. The Head Center mine, in the Tombstone district, Arizona, is on a vein which pierces slates, and in one place forty feet of limestone. In the slates it carried high-grade silver ores, with no lead, but in the limestone, lead-silver ores. A rock like limestone might well exercise a precipitating action, which, however, we cannot attribute to rocks composed of the more inert silicates. Again, it has been said that the solutions com- ing from below have varied in different portions of the vein or at different periods. An earlier opening would thus be filled with one ore, a later opening with another. This is hypothet- ical, but has been advanced for Klausen by Posepny.^ A fur- ther general objection to the first interpretation of lateral se- cretion is the weak dissolving power of cold surface waters, and this is a very serious one. 1.04.08. As opposed to the second interpretation, it may be advanced that precipitation in a cavity at a great depth would be retarded by the heat and the pressure, to just that extent to which solution in the neighboring walls would be aided. The temperature and pressure being practically the same, the ten- dency to remain in solution would be great until the minerals had reached the upper regions and filled the cavity by ascen- sion. Under such circumstances ores would only be deposited below, by some such action as replacement. To the third interpretation no theoretical objections can be made. 1.04.09. Infiltration by Ascension.' — On the side of infiltra- tion by ascension, if two veins or sets of veins were found in the same wall rock, but with different kinds of ores and miner- als, the conclusion would be irrefutable that the respective so- ' Archiv. f. Praktische Geologic, p. 483. 44 KEMP'S ORE DEPOSITS. lutions which formed them had come from two different sources below. Thus at Butte, Mont., there is a great development of a dark, basic granite. It contains two series of veins, of which one produces copper sulphides in a siliceous gangue, while around this series, to the south, west and north the veins yield sulphides of silver, lead, zinc, and iron, also in a siliceous gangue, but abundantlj^ associated with manganese minerals, especially rhodonite. No manganese occurs in the copper belt, nor is any copper found in the silver belt. Such results could originate only in different, deep-seated sources. Again, at Steamboat Springs, Nev., and Sulphur Bank, Cal., the hot springs are still in action and are bringing their burdens of gangue and ore to the surface. The former has afforded a long series of metals, the latter chiefly cinnabar. G. F. Becker^ has shown that the cinnabar probably comes up in solution with alkaline sulphides. 1.04.10. Replacement. — The conception of replacement is one that has been applied of late years by some of the most re- liable observers- Aboiit 1873 it appears to have been first ex- tensively developed by Franz Posepny, an Austrian geologist, in relation to certain lead-silver deposits at Raibl, in the Prov- ince of Kaernthen. At nearly the same time it was suggested by Pumpelly, then State Geologist of Missouri, to Adolph Schmidt, who was engaged in studying the iron deposits of Pilot Knob and Iron Mountain (see Examples 11 and 11a), and by Schmidt it was considered applicable to them.'^ Some ten years later J. S. Curtis, at the suggestion of S. P. Emmons, based his explanation of the formation of the Eureka, Nov., lead-silver deposits on the same idea, and according to Em- mons (1886) it holds good for Leadville. R. D. Irving, who credited Pumpelly with bringing it to his attention, published in 1886 an explanation of the hematite ores of the Penokee- Gogebic range (Example 9c), in which the idea is applied, and Van Hise has since elaborated it. In the process of replace- ment no great cavity ia supposed to exist previously. There is little, in fact, but a circulation or percolation of ore- ' G. F. Becker, "Natural Solutions of Cinnabar, Gold, and Associated Sulphides," Amer. Jour. Sci., III.,xxxiii. W9 ■ Eighth Ann. Rep. Director U. 8. Geol Survey. Monograph XIII. , U. S. Oeol. Survey, p. 343. ^ "Iron Ores and Coal Fields,'' Missouri Geol. Survey, 1873. ON THE FILLING OF MINERAL VEINS. 45 bearing solutions which exchange their metallic contents, molecule by molecule, for the substance of the rock mass. We would not ordinarily expect the ore body to be as sharply defined against the walls as when it fills a fissure, but rather to fade into barren material. Thus rock may be impregnated but not entirely replaced, and, while apparently unchanged, yet carry valuable amounts of ore. Some of the ores of Aspen, Colo. (Example 30d), are at times only to be distinguished by assaj' from the barren limestones. Yet decomposition may bring out the limits of each. 1.04.11. The chemistrj' of the replacement process is none too well understood, but it presents fewer difficulties when ap- plied to a soluble rock, like limestone or dolomite, than when rocks composed of silicates and quartz have given way to ores. Acid solutions would readily yield to calcium carbonate; but if the metals are present as sulphides, some reducing agent, such as organic matter, is necessary in order to change the me- tallic sulphate to sulphide.^ Or else, if the metallic sulphides come up in solution with alkaline sulphides, some third agent is needed to remove the calcium carbonate, pari passu just be- fore the metallic sulphide is precipitated. It must be con- fessed that for enormous bodies of ore, like those of Leadville, the small amount of organic matter present seems hardly equal to the task assigned it, and the delicate balance of the latter case— causing deposition to tread so closely on the heels of rock removal, in order to avoid assuming an extended cavity — makes it appear that the entire chemistry of the process is per- haps hardly understood. 1.04.12. When silicate rocks are replaced, leaving a sili- ceous gangue, the process may have been somewhat as sug- gested by R. C. Hills for the mines of the Summit district, Rio Grande County, Colorado.^ Alkaline solutions remove silica and have slight action on silicates, but solutions acid with sulphuric acid attack silicates, such as feldspar and biotite, change the alumina to a soluble sulphate, and cause the separation of free silica. In the alteration products abun- ' Compare S. F. Emmons, ' ' On the Replacement of Leadville Lime- stones and Dolomites by Sulphides," Monograph XII., U. S. Oeol. Survey, p. 563. ' See Proc. Colo. Sol Soc, Vol. I., p. 20. 46 KEMP'S ORE DEPOSITS. riant opportunity would be afforded for the precipitation of sulphides, which would in part at least replace the rock. Along a crack or line of drainage definite walls would thus easily fade out. Such phenomena are afforded by innumerable ore deposits^ and often come under the notice of every one familiar with mining. Yet we cannot but hope that in the future our knowledge of the chemical reactions involved will be increased. It may a,gain be stated that the formation of ore deposits has proceeded with great slowness, and that the solutions bringing the metals have been, beyond question, very dilute. The ex- tremely small amounts of the metals which have been detected in relativelj' large amounts of igneous rocks, even by the most refined analytical methods, have necessarily made the progress of solution a protracted one. Curtis records some careful observ- ations on the growth of aragonite at Eureka, Nev., where he found that in three weeks, so long as wet by a drop of water, the crystals increased in one case as a maximum five-eighths of an inch, and in another three-eighths. But this was where the whole inclosing mass of rock consisted of the compound deposited. ' See R. W. Raymond, discussion of S. F. Emmons' "Notes on the Geology of Butte, Mont.," Trans. Amer. Inst. Min. Eng., XVI., p. 59, 1887. CHAPTER V. ON CERTAIN STRUCTURAL FEATURES OF MINERAL VEINS. 1.05.01. Banded Structure. — ^Mineral veins sometimes ex- hibit a banded struciire, by which is understood the arrange- ment of the ore and gangue in parallel layers that correspond on opposite walls. They are most conspicuous where the walls are well defined. The solutions which have brought the min- erals have varied from time to time, and the precipitated coat- ings correspond to these variations. They alternate from gangue to ore, it may be, several times repeated. The ore may be in small scattered masses preserving a distinct lineal arrangement in the midst of the barren quartz, calcite, barite, fluorite, siderite, etc., or itself be so abundant as to afford continuous parallel streaks. The commonest ores so observed are pj^rite, chalcopyrite, galena, blende, and the various sul- phides of silver. The veins of the Reese River district, in Ne- vada, furnish good illustrations of alternating ruby silver ores and quartz. Those of Gilpin County, Colorado (Example 17a), afford alternations of pyrite, chalcopyrite, and gangue. (See figures in Endlich's report, Hayden's Surrey, 1873, p. 380.) The Bassick mine, in Colorado, has pebbles remarkably coated. Figure 6 shows a vein at Newman Hill, near Rico, Colo. Banded veins, however, except of a rude character, are not common in this country. They have received much more at- tention in Germany, where, especially near Freiberg, they show remarkable perfection. The famous Drei Prinzen Spat Vein, Fig. by Von Weissenbach and copied in many books, has ten corresponding alternations of six different minerals on each wall. Banded structure, whether of veins or vuggs or stalactites, etc., has bee'n called "crustification" by Posepny, who considers it an infallible symptom of deposition from solution. 48 KEMP'S ORE DEPOSITS. 1.05.02. A line of cavities, or vuggs, is often seen at the central porfcion of a vein, into which crystals of the last- formed minerals protrude, forming a comb (see Fig. 6). These may pro- ject into each other and interlock — especially in quartz — form- ing a comb in comb. The same may occur between side lay- ers. These cavities are a most prolitic source of finely crystal- lized minerals. If, after the fissure — perhaps at the time small — ^has become once filled, subsequent movements; take place, it may strip the vein from one wall and cause a new series of minerals to be deposited, with the previously formed vein on one side and the wall rock on the other. This occasions un- symmetri'cal fillings. But it may also happen that, with other- FlG. 6. — Banded Vein at Newman Hill, near Rico, Colo. After J. B- Farish, Proe., Colo. Sci. Soc.. April 4, 1892; Engineering and Mining Journal, August SO, 1892. wise symmetrical fillings, one layer may be lacking on one side cr the other. Where portions of the wall rock have been torn off by the vein matter in these secondary movements, they may be buried in the later deposited vein filling, and form great masses of barren rock called "horses." The vein then forks around them. If the ore and the gangue have partly replaced the wall in deposition, unchanged masses of wall may also become inclosed and afford horses of a different origin. An originally forked fissure gives an analogous result. It is a curious fact that veins are often most productive just at the split. If the masses are small, or if the vein fills a shat- ON STIiUGTUiiAL FEATURES OF MINERAL VEINS. 49 tered strip and not a clean fissure, or if it occupies an old vol- canic conduit, deposition and replacement may surround un- changed cores of wall rock with concentric layers of ores and minerals. Thus the Bassick, at Rosita, Colo., referred to above, consists of rounded cores of andesite, inclosed in five concentric layers of metallic sulphides. The Bull Domingo, in the same region, exhibits shells of galena and quartz mantling nodules of gneiss. Such cores strongly resemble rounded, water-worn boulders, a similarity which has suggested some rather improb- able hypotheses of deposition. 1.06.03. Clay Selvage. — An extremely common feature is a band of clay, most often between the vein matter and the wall. This is called a selvage, gouge, flucan, clay seam, or parting. It may come in also between layers of different min- erals, and may even rest as a mantle on tlie crystals which line cavities. It is at times the less soluble portion left by the de- cay and removal in solution of wall rock (residual clay), at times the comminuted material resulting from the friction of moving walls (attrition clay), and again it may be taken up by currents and redeposited from bodies of the first two sorts. Such layers of clay, being well-nigh impervious to water, may have exercised an important influence in directing the subterra- nean circulations.' 1.05.04. Pinches, Swells, and Lateral Enrichments. — The swells and pinches of veins have been referred to above and ex- plained. Aside from these thicker portions of the ore, it is often seen that the richer, or even the workable bodies follow certain more or less regular directions, forming so-called "chutes." They probably correspond to the courses taken and followed by the richer solutions. J. E. Clayton observed that they follow the directions of the slips, or strise, of the walls rather more often than not, and in the West this disposition or tendency is called Clayton's law. Chute is sometimes spelled "shoot" or"shute." Chimney and ore-course are synonyms of chute. Bonanza is used, especially on the Comstock Lode, to indicate a localized, rich body of ore. Lateral enrichments are caused by the spreading of the ore- bearing currents sidewise from the vein, and often along par- ticular beds of rock, which they may replace more or less with ' See citation from Beckei' on the Comstock Lode, 2.11.19. 50 KEMP'S ORE DEPOSITS. ore. Beds of limestone— it may be quite thin, when in a series composed of shales or sandstones — are favorite precipitants, and from such lateral enlargement the best returns may be ob- tained. The valuable ore bodies of Newman Hill, near Eico, Colo., whose interesting descriptions by J. B. Farish and T. A. Rickard have already been several times cited, are found as lateral enrichments along a bed of limestone less than three feet thick and embedded in shales. Above the limestone the veins practically cease, as the fissures become tight in a series of sandstones and shales. Lateral enrichments may closely re- semble bedded deposits if the supply fissures are relatively small, but it is generally safe to infer the presence of supply conduits, although they may be obscure. The Potsdam ores of the Black Hills are good illustrations. 1.05.05. Changes in Character of Vein Filling.— In dis- cussing the influence of wall rock the changes that occur in veins were briefly mentioned. But even where the walls re- main uniform there is always variation in contents, and of course in value, from point to point. Ore, gangue, horses, and walls alternate both longitudinally and in depth, and such changes must be allowed for and averaged by keeping explora- tion well in advance of excavation. Even a series of parallel veins may all prove flckle. In illustration of the above the Marshall tunnel of Georgetown, Colo., may be cited. It cut twelve veins below their actual workings, and every one was barren at the tunnel though productive above.' 1.05.06. Secondary Alteration of the Minerals in Veins. — It has already been stated that the chief ore minerals in vein fillings are sulphides. Where these lie above the line of per- manent subterranean water they are exposed to the oxidizing and hydrating action of atmospheric waters, which, falling on the surface, percolate downward. The ores are thus subjected to alternating soakings and dryings which encourage altera- tion. The sulphides change to sulphates, carbonates, oxides, or hydrous forms of the same, and the metallic contents are in part removed in the acid waters which are also formed. Py- rite, which is the most widespread of the sulphides, becomes limonite. staining everything with its characteristic color. Galena becomes cerussite or anglesite. Blende affords cala- ' J, J. Stevemson, Wheeler's Survey, Geology, Vol. III., p. 351. ON STRUCTURAL FEATURES OF MINERAL VEINS, 51 mine and smithsonite. Copper ores, of which the usua] one is chalcopyrite, change to malachite, azurite, chrysocoUa, cuprite, and melaconite, and to the sulphide, chalcocite. The silver sul- phides afford cerargyrite. The rarer metals alter to correspond- ing compounds of less frequency. These upper portions are also more cellular and porous, being at times even earthy. The rusty color from the presence of limonite often marks the outcrop and is of great aid to the prospector. It has been called the iron hat, or gossan. This feature has important economic bearings. The character of ores may entirely change at a defi- nite point in depth, and the later products, if not lower in grade, as is often the case, may demand different, perhaps more difficult, modes of treatment. Oxidized ores are the easiest to smelt, and the desirability of careful exploration before indulg- ing in too confident expectations may be emphasized. As exam- ples, the Ducktown copper deposits (See Example 16), the Leadville silver mines (Example 30), the southwest Virgii^ia zinc deposits (Example 26), tbs copper and silver veins at Butte, Mont. (Example 17), and others in Llano County, Texas (Example 17fo), may be cited. At Ducktown a con- siderable thickness of chalcocite, melaconite, and carbonates accumulated just at the waterline and abruptly changed to low-grade, unworkable pyrite and chalcopyrite below it. At Bonsacks, near Eoanoke, Va., very rich, easily treated, earthy limonite and smithsonite (.30 to 40 per cent, zinc) passed into a refractory, low grade (15 to 20 percent, zinc), intimate mixture of blende and pyrite. Excavations in dry districts may not reach the water line for great depths. Thus at Eureka, Nev., in the rainless region of the Great Basin, the oxidized ores con- tinue to 900 feet or more. It is worthy of remark in this connection that possibly some deposits of oxidized ores may have been formed originally as such. Wendt has argued this for the copper mines of the Bis- bee district, Arizona ; but in this case recent exploration has established the former presence of sulphides. (See Example 20/*. ) If oxidized ores are now found below the water line, it may indicate a depression of the rocks from a previous, higher position. E. C. Hills has brought out a very interesting in- stance of the concentration of gold and silver in the lower part of the oxidized zone, or at least at a considerable depth 52 KEMP'S ORE DEPOSITS. below the outcrop. The upper portion of the vein, in this case with a quartz gangue, was impoverished. The gold is thought to have been carried down in solution with ferrous and ferric sulphates, which were decomposed by feldspar, while the precious metal was thrown down. The ore bodies lie in the Summit district, ' Rio Grande County, Colorado. 1.05.07. The waters of mines which have opened up and exposed sulphides to oxidation are often charged with sul- phuric acid and even metallic salts. This is especially true of mines in copper sulphides, and the pumps are much corroded. In instances considerable metallic copper has been removed by passing the mine drainage over scrap iron, as at Ducktown, Tenn., and as has been introduce^ at Butte, Mont. Mine timbers have been preserved very long periods by the deposi- tion of copper on them, because of their reducing action on the solutions. Pumps and timbers placed by the Romans in the Rio Tinto mines, in Spain, are still in good preservation. Even gold has been detected in Australian mine waters.^ 1.05.08. Electrical Activity.- — ^ Among the writers of fifty or sixty years ago, electrical or galvanic action was a favorite theoretical precipitant of ores in veins, and careful experi- ments were made in England and Germany to detect it. By connecting the opposite ends of a vein with a wire, in which was a galvanometer, the attempt was made again and again to establish the existence of galvanic action. At times the results gave some grounds for belief, but at others they were contradictory or uncertain, so that no very definite or reliable cohclusions were established Other experiments were made in Germany about 1844, by Reich, while lately quite elaborate investigations have been carried out by Dr. Carl Barus on the Comstock Lode, and at Eureka, Nev. Great diflSculties are met in preserving the necessary insula- tion throughout the wet and devious underground workings, ' R. C. Hills, Proe. Colo. Sci. Soc, Vol. I., p. 33; S. F. Emmons, quot- ing Hills, Engineering and Mining Journal, June 9, 1883. For a very complete discussion of the alteration of ore deposits above the ground water and of the formation of gossan minerals, see E. A. F. Penrose, Jr., "The Superficial Alteration of Ore Deposits," Journal of Geology, II. 288, 1894. ' See School of Mines Quarterly, V9I. XI., 364, for review of literature bearing on this subject. ON STRUCTUBAL FEATURES OF MINERAL VEINS. 53 and amid such surroundings in detecting the currents, which would be necessarily small. With Earns the thesis was not alone to establish a galvanic action, such as might be a precipi- tating agencj', but also to observe what effect, if any, was ex- erted by the intervention of an ore bodj' on the normal terres- trial currents. Had this latter been proved of sufficient amount, the existence of such bodies might be indicated by plotting electrical observations. While in some respects of interest, the results of Dr. Barus are not very decisive, and this line of in- vestigation is hardly to be considered a promising one. The importance attached to it in former j-ears may be illustrated by these words of De la Beche, one of the ablest of English writers, in 1839. Speaking of veins in general, after discussing those of Cornwall in particular, he says: "Mineral veins result from the filling of fissures in rocks by chemical deposits, from substances in solution in the fissures, such deposits being greatly due to electro-chemical agency." The influence of ter- restrial magnetism upon the distribution of mineralized dis- tricts has been urged by T. F. Van Wagenen, vs'ho endeavors to show for the Cordilleran region of North America that the productive areas lie along mean magnetic curves and that they are separated by barren belts. The productive belts are thought to converge at the magnetic pole of the earth north of Hudson Bay.^ ' Theo. F. Van Wagenen, "System in the Location of Mining Districts," School of Mines Quarterly, January, 1898, p. 109. CHAPTEE VI. THE CLASSIFICATION OF ORB DEPOSITS — A REVIEW AND A SCHEME BASED ON ORIGIN. 1.06.01. In the classification of ore deposits the same syste- matic arrangement is not to be expected as in the grouping of plants, animals, or minerals. Ore deposits have not the under- lying affinities and relationships of living organisms nor of defi- nite chemical compounds. The series of objects is too diverse, and, in the nature of the case, the standards of appeal must be different. The subject is, however, one of great practical impor- tance as well as of great scientific interest. A vocabulary of intelligible terms is indispensable for description and compari- son, and, under our mining laws, often for valid titles, while as a vehicle for the spread of knowledge and reasonable con- ceptions regarding these phenomena, its importance cannot be overestimated. 1.06.02. All schemes of classification rest on these princi- ples: form, origin — or the genetic principle (including method, relative time of origin as contrasted with the walls, etc.) — state of aggregation, and mineral contents. Oi these, the principle ,of form is usually esteemed the weightiest, and is given the great- est prominence, partly because it has been thought to be the one most closely affecting exploitation, and partly because it involves less that is or has been, up to very recent times, more or less hypothetical. Yet form is largely fortuitous, and it has, of course, no law, while, with sufficient knowledge, the genetic principle is the one giving a far more thoroughly scientific basis. Everyone, in opening up or searching for an ore body, must be influenced by some hypothesis, either of shape or of origin. It is the conviction of the writer that, with all our de- ficiencies of knowledge, the genetic principle is also the best guide, even in practical development. GLAS8IFIGATI0N OF ORE DEPOSITS. 55 1.06.03. Very early in the development of mining litera- ture the distinction was made between those ore bodies which are parallel to the stratification and those which break uncon- forma,bly across it. This took place long before the epoch-mak- ing time of Werner, and even before the conception of the rela- tive ages of strata had been at all generally grasped. Thus among the Germans we find the terms "Lager" and "Flotze"^ on the one side, being set off in contrast to "Gang" (vein) on the other. Werner, writing in 1791, quotes Von Oppel's distinctions between Flotze (strata beds) and Gauge (veins), which Avere published in 1749; but without doubt, as mining terms, they go much further back. Beyond this simple indica- tion of the views of the older writers, no attempt will be made here to quote authorities earlier than 1850. This is justifiable, because the important works, like De la Beche'a Geology of Cornivall and Devon, and Henwood's Metalliferous Deposits of Cornivall and Devon, are rather discussions of veins than systematic attempts at classification. 1.06.04. In Appendix I. will be found the principal schemes of classification which have thus far been suggested. They are grouped according to certain relationships and similarities that run through them. The scheme here given finds its natural ' Lager and Flotze are difficult to render into English while retaining their native shades of meaning The later writers in Germany (Serlo, Gatzchmann, Von Groddeck, Kohler) define them as being interbedded bodies, each later than the foot wall in formation, and older than the hanging; and that Lager are much more limited in horizontal extent than Flotze R. VVabner shows, however, intheJSerg.- u. Hut. Zeitung, Jan. 2, 1891, p. 1, that writers in the earlier part of the century did not entirely restrict the term Lager as regards age relative to the foot and hanging, but apphed it to ore bodies, which follow the general bedding, although they may have been introduced much later than the formation of the walls. Thus the frequent occurrence of lead ores in Mmestone along certain beds (southeast Missouri for example) would be called Lager. We would apply the terms impregnation, or dissemination, or bed-vein, to such. Flotze we would call stratum, and Lager, as defined by the later authors "bed" or "seam." Werner, for instance, in his classification of the rock formations of the globe, made : I. Urgebirge (Primitive, Primary, etc., having no fossils) II. Secondary, subdivided into A. Ueber- gangggebirge (transitional, more or less metamorphosed sediments, but fossiliferous). B. Flotzgebirge (unaltered strata). From this the mean- ing of Flotz may be grasped. By contrast, a magnetite lens is a good illustration of Lager. 56 KEMP'S ORE DEPOSITS. place as No. 17, and at the time that it was first prepared it ^Yas unique in being a purely genetic one, except that one by F. D. Power, which appeared in Melbourne the same year, ran along the same lines. The literature of the next few years proved, however, that the subject was active in many minds, and other schemes were independently published in different parts of the world, which were conceived from the same point of view. In the one below, the four important methods of origin, viz., the igneous, the methods of precipitation from solution or by depo- sition from suspension or by deposition as residual concentra- tions, are made fundamental and then the ore-bodies belonging under each are referred so far as possible to well-recognized and familiar geological phenomena. The close analogy of this grouping in some of its particulars to the commonly accepted classification of rocks, will beat once apparent, and our general knowledge of rocks may be used to throw light upon the ore deposits, but the latter with the exception of a few involving iron, are never in sufficient amount to be considered particular forms of rock, in and of themselves. The scheme is also the natural result of the general exposition of the subject in the preceding pages, which have consistently led up to it. Certain obscure ore bodies, which are not well understood, receive spe- cial mention after the general discussion. 1.06.05. J. F. Kemp, 1893. Eevised from the Scliool of Mines Quarterly, November, 1892. I. Of Igneous Origin. Excessively basic develop- 'ments of fused and cooling magmas. Peridotite, forming iron ore at Cumberland, Rhode Island.' Titaniferous magnetite, Jacupiranga, Brazil f in Minnesota gabbros;^ in Adirondack gabbros;* in Swedish and Norwegian gabbros." Nickeliferous pyrrhotite.^ Chromite.' Corundum.' ' M. E. Wadsworth, Bull. Mus. Comp. Zool, 1880, VII. ^ O. A. Derby, Amer. Jour. Soi., April, 1891. ^ N. H. Winchell, Tenth Ann. Rep Minn. Oeol. Survey, pp. 80-83, Bull. VI. of same survey, p. 135. ' J. F, Kemp, Bull. Oeol. Soc. Amer., V. 332, 1894. XIX. Annual Rep. Dir. U. S. Geol. Survey. (In press, March, 1899. ) ' J. H. L.Vogt, Oeol. Foren. i. Stockholm Forhand, XIII., 476, May, 1891. English abstract and review by J. J. H. Teall, Geol. Mag., February, 1893, See also Zeitschr. fur Praktisohe Oeologie, I. , 4. " See references under paragraph 1.06.08 below. ' See references under paragraph 1.06.13. CLASSIFICATION OF ORE DEPOSITS. 57 II. Deposited from solutiou. 1. Surface precipitations, often forming beds and caused by — ■ . (a) Oxidation. Bog ores. Ferruginous oolites, as in some Clinton ores.^ (&) Sulphurous exhalations from decaying or- ganic matter, etc. (Pyrite.) (c) Reduction, chiefly by carbonaceous, organic matter. (Pyrite from ferrous sulphate.) (d) Evaporation, cooling, loss of pressure, etc. Hot spring deposits, as at Steamboat Springs, Nev.^ (e) Secretions of living organisms. (Iron ores by algsB.' Note. — These same causes of precipitation operate in sub- terranean cavities, although not again specially referred to. 2. Disseminations (impregnations) in par- ticular beds or sheets, because of— (a) Selective porosity. (Silver Chff, Colo., sil- ver ore in porous rhyolite.* Amygda- loidal fillings as in copper-bearing amyg- daloid. Keweenaw Point, Mich. ; Santa Rita, N. M.'"^ Impregnations of porous Sandstone as at Silver Reef, Utah." (&) Selective precipitation by calcareous matter. Potsdam or siliceous gold ores, Black Hills, S. D.' 3. Filling joints caused by cooling or dry- ing (Mississippi Valley gash veins in part). ' C. H. Smyth, Jr., Amer. Jour. Soi., June, 1893, p. 487. ' G. F. Becker, Monograph XIII., U. S. Geol. Survey, pp. 331, 468;Laur, Ann. des Mines, 1863, p. 421; J. Leconte, Amer. Jour. Sci., June, 1883, p. 424, July, p. 1 ; W. H. Weed, idem, August, 1891, p. 166. = Sjogrun, Berg.- und Hutt. Zeit., 1865, p. 116. ' Clark, Engineering and Mining Journal, Nov. 2, 1878, p. 314. • A. F. Wendt, Trans. Amer. Inst. Min. Eng. , XV. , 27, " C. M. Eolker, idem, IX., 21. ' J. D. Irving, Annals N. Y. Acad. Sci., XII. Part II, 1899. Other cita tions will be found under 2,01.03. 68 KEMP'S ORE DEPOSITS. 4. Occupying chambers (caves) in lime- stone. (Cave Mine, Utah.' ) 5. Occupying collapsed (brecciated) beds, caused by solution and removal of sup - port, or from dolomitization of lime stone. (Southwest Missouri zinc depos- its.^ Occupying cracks at Monoclinal bends. Anticlinal summits. Synclinal troughs, often with replacement of walls. (Gash veins in part; galena deposits at Mine la Motte, Missouri; zinc blende deposits in the Saucon Valley, Pennsylvania.') Elkhorn Mine, Mont. 6. Occupying shear-zones, or dynamically crushed strips along faults, whose dis- placement may be slight, closely related to No. 8. (Butte, Mont.)' 7. True veins filling an extended fissure, often with lateral enlargements. See also under 5. 8. Occupying volcanic necks, in agglom- erates. (Bassick Mine, near Rosita, Colo.)' 9. Replacements in troughs of some im- pervious rock or rocks. (Lake Superior hematites. )° 10. Contact deposits. Igneous rocks always form one wall. Fumaroles. (Greisen.) ' J. S. Newberry, School of Mines Quarterly, March, 1880. See also J. P. Kimball, on Santa Eulalia, Chihuahua, Amer. Jour. Sci., II., xlix. 161. " F L. Clerc, Lead and Zinc Ores in Southwest Missouri Mines, Carthage, Mo., 1887; A. Schmidt, Missouri Oeol. Survey, 1874, p. 384. See later papers cited under Example 25. = F. L. Clerc, Mineral Resources, 1883, p. 361 ; H. S. Drinker, Trans. Amer. Inst. Min. Eng., I., 367. ■* S. F. Emmons, Trans. Amer. Inst. Min. Eng., XVI., 49; W. P. Blake, Idem, XVI., 65. Butte Special Folio, U. S. Oeol. Survey. » C. W, Cross, Proc. Colo. Sci. Soc, 1890, p. 269. S. F. Emmons, XF/I. Pep. U. S. Oeol. Surv., Part II., p. 430. ' C. E. Van Hise, Amer. Jour. Sci., February, 1893, p, 116. Monograph XXVIII V. S. Oeol. Surv. CLASSIFICATION OF ORE DEPOSITS. 59 11. Segregations formed in the alteration of igneous rock. (Chromite in serpen- tine.) III. Deposited from Suspension. Residual Deposits. 1. Metalliferous Sands and Gravels, whether now on the surface (placers, magnetite beach sands), or subsequently buried. (Deep gravels, magnetite lenses?) 3. Residual Concentrations, left by the weathering of the matrix. (Iron Moun- tain, Mo., hematite in part.') 1.06.06. It is believed that under the above heads are in- cluded all the forms of ore bodies which constitute well-recog- nized and fairly well-understood geological phenomena. To these categories year by year we are enabled, by the results of extended and careful investigation, to refer many that have been obscure. A number of familiar terms for ore bodies in mining literature fail to appear, but are mentioned in the classifications quoted from others. (See Appendix I.) Many of these refer only to form, and geologically considered are only convenient admissions of ignorance as to origin. Some other ore bodies whose methods of origin are involved in the processes of regional metamorphism are placed by themselves further on. The explanations of them are as yet hypothetical. A few com- ments on the scheme may now be added, although in the main it explains itself. 1.06.07. I. The writings of Lagorio, Iddings, Rosenbusch and others, regarding the development of rocks from fused magmas, have emphasized the fact that the laws of solution do not fail to apply, because the magmas are raised to very ele- vated temperatures; and that they hold good for fused rock precisely as for heated water or any other solvent. Other laws of physical chemistry and of thermodynamics have also been recognized by many as fundamental to the true imderstanding of the reactions, but the subject is a difficult one, and our knowl- edge is as yet incomplete. The reactions are complex and occur at such elevated temperatures as to render observation difficult. The magmas known in Nature are of endless va- ' R, PumpeUy, Bull. Geol. Soc. Amer., II., p. 220. 60 KEMP'S ORE DEPOSITS. riety, and involve a number of bases. Just which portion is solvent and which is dissolved matter may not always be clear, nor do we certainly know the actual state in which the ele- ments exist at these high temperatures, nor the influence of electrical currents or still more obscure forces. Nevertheless, we do know that as the magma cools from a perfectly fluid condition the first minerals to separate are those which first, under the diminishing temperature (and perhaps pressure) reach a state of saturation and must therefore crystallize. If this is expressed in the terms of thermodynamics, we may say that those compounds will first form which liberate the most heat in crystallizing, and so on down to complete solidification. Usually the order is that described in paragraph 1.0.3.05, but mass action, brought about by the superabundance of one ele- ment or another, may affect the order, and the variability of composition shown by igneous rocks is also a serious factor. Students of rocks have very generally reached the conclusion that a great parent magma which stands molten for long pe- riods in the earth will break up into different component or fractional magmas before any mineral crystallizes. The frac- tional magmas by successive eruptions afford various different types of rocks of greatly contrasted composition. The process is called differentiation, and it is of interest in this connection as showing in a general way the tendency of fused rock masses to break up and vary. All the above theoretical considerations throw light on the formation of the igneous ore bodies. 1.06.08. The first ore bodies to which an igneous origin was attributed in the past were those portions of a basic intru- sion, such as a peridotite or a gabbro, which were so enriched with magnetite as to become an ore. The magnetite is almost always titaniferous and may indeed be ilmenite. The classic occurrence of this type is Taberg,^ in Sweden, where a great boss of basic igneous rock 1..5 kilometers (1.3 miles) long, 0.5 kilometer (0.4 mile) broad and 130 meters (400 ft.) high is ' A. Sjogren, Ueber das Eisenerzvorkommen von Taberg in Smaland, Geol. Foren. in Stockholm, Forhandl, III., 42-62, 1876, and VI., 1882; Neues Jahrbuch, 1876, 434. A E. Tornebohm, Om Taberg i Smaaland och ett par dermed analoga jernmalmforekomster. Idem, V. 610-619, 1881. Neues Jahrbuch, 1883, II., 66 CLASSIFICATION OF ORE DEPOSITS. 61 found intruded in granite-gneiss, with its long axis parallel to the foliation. In the central part of the boss is found the ore, a mixture of titaniferous magnetite and olivine, but the boss shades from ore, outwardly, by the increase of feldspar to the variety of gabbro, called hyperite in Sweden. In the basic core and acidic rim the boss differs from most intrusions, because the latter shade from acidic cores to basic rims. The Cumberland ore, Rhode Island, forms a boss of titaniferous magnetite mingled with olivine and pyroxene. It is much like that of Taberg. The ore of Brazil is strongly titaniferous, but occurs in basic rocks with nepheline, and much the same is true of Alno, Sweden,^ where nepheline syenite is the geological asso- ciate. In the Adirondacks, and in Minnesota, Quebec, Wyo- ming and Norway, huge masses of quite pure titaniferous magnetite occur in anorthosite gabbros. As a peculiar phase of the Cortlandt series of gabbros on the Hudson River, near Peekskill, there are richly aluminous, but feebly titaniferous ores which consist of spinel, corundum and titaniferous mag- netite. At Routivara, Sweden,^ practically the same aggre- gate has been found. 1.06.09. In addition to the igneous magnetites, chromite has been met by Vogt in an outcrop of unaltered peridotite within the Arctic circle, in Norway,'' and J. H. Pratt' attri- butes the same method of origin to the chromite of North Carolina, although hitherto chromite in serpentine has usually been considered a segregation produced during the weathering of rocks which possess chrome-bearing silicates. Corundum is now recognized in a few places as a result of crystallization from fusion. The special conditions of its formation will be noted below. 1.06.10. Aside from the metallic oxides just cited, certain great deposits of metallic sulphides, and especially of chalcopy- rite and nickel-bearing pyrrhotite, are likewise regarded as the products of crystallization from fusion. Many Norwegian lo- ' A. G. Hogbom, Ueber das Nephelinsyenitgebiet auf der Insel Alno. Oeol. Foren. Forhandl, XVII., 100, 214, 1895, Neites Jahrbuch, 1896, I., 252. ' W. Peterson, Geol. Foren. Forhandl, XV., 45-54, 1893. H. Sjogren, Ibid., 55, 140-143. ' J. H. L. Vogt, Zeitsch. fur prakt. Oeologie, January, 1894, p. 389. ' J. H. Pratt, Engineering and Mining Journal, Dec. 10, 1898, p. 696 Trans. Amer. Inst. Min. Eng. (issued May, 1899). 62 KEMP'S ORE DEPOSITS. calities and in America the Gap Mine, Pa. ; the Sudbury mines, Ont., are of this type. The gold-bearing pyrrhotites of Rossland, British Columbia, resemble it, but have also been esteemed replacements. All these sulphides are found in the outer portions of the intrusions. 1.06.11. In discussing the chemical and physical processes which have led to the production of the igneous types of ore bodies, it is important to emphasize their position with regard to the mass of the intrusion,'' i.e., whether in the center or at some other point well within the intrusion, or whether in the outer portions near the contacts. Somewhat different processes may be invoked in explanation according to these several relations. 1.06.12. The titaniferous magnetites are either centrally placed or else are so far within the mass as to show no relations to its borders. They are also merely exceptional and local en- richments of the magma with one of its more abundant compo- nent bases, and with a particular mineral, which is arnong the earliest to separate in the process of crystallization, and which has the highest specific gravity of any of those entering into the rock. Morozewicz' has sought by artificial experiments to determine the laws which govern its separation, but he finds them complex. The experiments indicated that mass action played a prominent part, and that with an abundance of the iron oxides the crystallization of the magnetite preceded that of the ferromagnesian silicates; with less it began after them. The iron oxides enter as bases into so many rock -forming min- erals that enough to satisfy the ferromagnesian group is obvi- ously necessary before large amounts of magnetite can be ex- pected. If, therefore, we assume a magma excessively rich in iron together with much magnesia, but low in lime, alumina and alkalies, an aggregate of magnetite, olivine and some pyroxene will necessarily result on crystallization, as at Taberg and Cumberland. To explain, however, the central position of this basic portion in an otherwise more acidic, average magma is not so simple. If again we assume a magma fairly rich in iron, soda, lime, alumina, and silica, but lacking magnesia, it is conceivable that magnetite and labradorite will result as in the anorthosites. The concentration of the magnetite seems to ' Josef Morozewicz, Experimentelle Untersuchungen iiber die Bildung der Minerale im Magma. Tschermaks Mittlwihmgen, XVIII,, 84, 1898. OLASSIPiaATION OF ORE DEPOSITS. 63 the writer best explained by its settling in the still molten mass until it has formed considerable aggregates. When once these rich aggregates have formed, they may in the process of erup- tion or intrusion take almost any place in the resulting rock/ Physico-chemical reactions may, however, be operative of which at present we are not aware. Vogt^ has suggested that when magnetite crystals have formed in the still molten magma they may become aggregated by their magnetic attrac- tions, but the mineral loses its magnetism even at a temper- ature below redness, and it is doubtful if this property could affect the result. 1.06.13. Chromite appears at times in masses well within the peridotite or serpentine which contains it, and it also is no- ticeably abundant near the contact' in other occurrences. Corundum furnishes a close parallel. It has been met in very great quantity in Ontario,' north of Lake Ontario, in nephe- line-syenite, favoring certain varieties of the rock, but dis- tributed all through it. In North Carolina^ it favors the outer portions of the peridotite (dunite) in which it is found. Sap- phires of gem quality have been found in Montana in a basic dike consisting chiefly of biotite, diopside and magnetite. Some secondary products from unrecognizable originals are also present.^ The chemical conditions under which corundum separates from igneous magmas have been very clearly shown by Moroze- wicz.' Without regard to the percentage of silica in the rock, ' J. F. Kemp, "The Titaniferous Magnetites of the Adirondacks," etc., XIX. Ann. Bep. Dir. U. S. Geol. Survey (in press). ' Dannelse af Jemmalmforekomster, Kristiania, 1893, Resume in Ger- man, p. 145. Vogt also mentions the concentration by settling which is set forth above. 'J, H. Pratt, "The Occurrence, Origin and Chemical Composition of Chromite" (abstract). Engineering and Mining Journal, Dec. 10. 1898, p. 696. Trans. Amer. Inst. Min. Eng., February, 1899, New York meeting. Refers especially to North Carolina. * W. G. Miller, Report of the Ontario Bureau of Mines, VII., 307, 1898. " J. H. Pratt, " On the Origin of the Corundum Associated with the Peridotites in North Carolina," Amer. Jour. Sci., July, 1898, p. 49. ' L. V. Pirsson, " Corundum-bearing Rock from Yogo Gulch, Montana,'' Amer. Jour. Sci., December, 1897, p. 431. ' Jozef Morozewicz, Experimentelle Untersuchungen iiber die Bildung der Minerale im Magma, Tshermaks Mittheilungen, XVIII., 30, 1898. 64 KEMP'S ORE DEPOSITS. provided that it lies withiu the limits meb in natural magmas, free alumina will separate as corundum, when the molecular ratio of the alumina to the other bases is greater than unity, i. e., -r, r\ I t:>1\ ^ -d /- > greater than 1. In this case spinel mar K2(J-rK(J-r-tC2U3 be anticipated as an associate. When, therefore, corundum is found in a natural igneous rock this condition must have been met at the time it crystallized. As to the causes which have produced the concentration at the borders, the dis- cussion is the same as that given under the next topic. 1.06.14. The deposits of nickeliferous and auriferous pyr- rhotite and of chalcopyrite, which are found in the rims of basic intrusions, present, so far as mining is concerned, much larger developments than the chroniite and corundum just re- ferred to, and the important applications of nickel in armor- plate have led to careful study of the ores. They are recognized by most observers as crystallizations from fusion, and the prob- lem arises as to the causes which have brought them into their present position. That individual intrusions vary from a more acidic (or sili- ceous) composition at the center to a more basic one at the bor- ders is well established by observation and by progressive analyses in a number of instances.^ An explanation of these relations has been sought in what is known as Soret's principle.^ It was proved by experiments in 1879 by Soret, a French chemist, that if differences of tempera- ture are induced in a solution of common salt or other sub- stance in water, the dissolved material will become relatively concentrated in those portions in which the temperature is low- est. It has also been shown that this would follow from the laws of osmosis, and that the relative degrees of concentration ' See Lawson and Shutt, on a diabase dike in the Rainy Lake Region, Proc. Avier. Assoc. Adv. Sci., 1889, 246; Alfred Harker on an English, gabbro, Quarterly Journal of the Geological Society, 1894, 326; W. S. Bayley on Minnesota gabbros, Journal of Geology, III., 824, 1895. ^ The bearing of this explanation of magmatic differentiations in igneous rocks upon these nickeliferous deposits has been especially set forth by J. H. L. Vogt of Kristiania, Norway, in the Zeitschrift fiir Prdktische Geologic, I., 13,5, 1893, under the title "Sulphidische Ausscheidungen von Nickel-sulphid-erzen," etc. . Other related papers appear in the same, I. 4 and 257; 11. 41, 134 and 173. CLASSIFICATION OF ORE DEPOSITS. 65 would be to one another inversely as the absolute temperatures {i.e., temperature Centigrade plus 273). The lower the tem- perature, therefore, the more dissolved material would collect in such chilled portion. If now we consider a fused rock magma as a complex solution of several silicates, oxides, sul- phides and one or two rarer compounds, some in others, and if we regard as the least soluble those that crystallize first in the process of cooling, we are led by Soret's principle to infer that these would tend to become concentrated in the portions first cooled, and that in such- portions they would be especially abun- dant after consolidation. The portions of an igneous intrusion that are first cooled are obviously those next the wall rock. The minerals which crystallize first are, as set forth earlier under 1.03.05, magnetite, ilmenite, apatite, pyrite, pyrrhotite, and several minor ones. In the case of nickeliferous pyrrhotite the ore bodies are especially rich along or near the contacts of gabbroic and dio- ritic intrusions with their walls, and the paper of J. H. L. Vogt, cited in the footnote, has served to bring out some ex- tremely interesting facts. The geological relations are more frilly set forth later on under nickel and in connection with several American occurrences, but it may be here added that away from the outer wall the ore bodies fade (at least at the Gap Mine, Pa.) into barren gabbro, by a fairly gradual tran- sition. In these respects they conform quite closely to condi- tions which would result from a development according to Soret's principle. We also f nd in such ore bodies much the same association of minerals, wherever they are mined. Pyrrhotite is in greatest amount and contains the nickel and cobalt replacing a portion of its iron; as the rarer mineral pentlandite/ or as secondary coatings of millerite in cracks. Chalcopyrite is invariably present, often in important quan- tity. Vogt has sought to trace out some constancy in the rela- tive amounts of these several metals, but the attempt is not specially successful. He also cites in connecti on with a dis- ' S. L. Penfleld, "Pentlandite f rom Sudbury, Ont.," etc., Amer. Jour. Soi., June, 1893, 493. Pentlandite is a sulphide of iron and nickel, isometric, non-magnetic, and with a somewhat varying percentage of nickel, which reaches at Sudbury 34.33. The general formula from Penfield's analysis Is (NiFe)S. 66 KEMP'S ORE DEPOSITS. cussion of their early formation aad combination with sulphur in the fused magma, the laws which we know apply in the metallurgical processes involving slags and mattes.' 1.06.15. Admitting that the bases iron, nickel and copper, along with others, have been concentrated, while still in the state of ions,^ at the borders by Soret's principle, or by some other process, perhaps not clearly understood, objection has still been made to the igneous origin of sulphides, because it is believed that the conditions in a fused magma are oxidizing — as witness the presence of the several metals in almost all igneous rocks as oxides — and because oxidizing conditions would be inimical to the production of sulphides. When sulphides form in a furnace, it is urged that the fuel creates a reducing action, and that, otherwise, sulphides would be impossible. The analogy of a furnace is not to be too sharply urged in objection, for the reason that no blast of oxygen is blown through a magma, so as to create of itself an intense oxidation. The abundance, moreover, of ferrous oxide in basic rocks indicates that the oxidizing conditions are not marked. Nevertheless, to meet the objections to the formation of sulphides in mag- mas, while assuming the greater basicity of the outer portions of the mass, the writer' has suggested that the escape of sulphur- ous gases through the still molten rock along the contacts would produce sulphides of metals already there, even though the general conditions in the magma were oxidizing. In the original paper the reactions involved are justified on the basis ' As is well known the common metals may be ranged in the following order ("Fournet's Series ") according to their decreasing affinity for sul- phur, Cu, Ni, Co, Fe, Sn, Zn, Pb, Ag, Sb, As, see Vogt, Zeitsch. fur prakt. Geologie, I. 263. In their bearings on geological phenomena these metal- lurgical laws were discussed many years ago by Leonhard in Hilttener zeugnisse und andere auf Kimstlichem Wege gebildete Mineralien ah Siiizpunkte geologisher Hypothesen, Stuttgart, 1858. The succession is determined by the laws of thermo-ehemistry, and necessarily the sulphides svill form in order according to the amounts of heat developed by the reaction, from the greatest to the least. " The term ion is employed in modern chemistry to describe those par- tial molecules that are held in an incomplete state by electrical force. The word is derived from the Greek for "going" or "moving," and was suggested by the partial molecules that are in ti'ansit in an electroplating bath. ■ ' J. F. Kemp, Tha Mineral Industry for 1895, Vol. IV., 761-766. CLASSIFICATION OF ORE DEPOSITS 67 of physical chemistry, and the process conceived is analogous to bessemerizing a hath of oxides with sulphur vapor, as con- trasted with the usual artificial process of oxidizing a bath of molten sulphides with a blast of air. G. F. Becker^ has presented a strong argument against the ability of Soret's principle to accomplish serious results in ef- fecting a differentiation of an originally homogeneous fluid magma into others of different compositions, and cites in sup- port of his argument the slowness and feebleness of molecular flow and diffusion as indicated by artificial experiments with soluble salts. The viscosity of fused rock gives additional force to the objection. He therefore attributes^ the changes to. convection currents, which would be inevitably set up in the mass by its differences of temperature and which, as they passed along the cold surfaces inclosing the molten fluid, would coat them with the earlier and less mobile crystallizations." This process of "fractional crystallization" is beyond question a most important suggestion, and it may obviate some of the difficulties that have hitherto been serious. 1.06.16. As opposed to the igneous view others have re- garded ores of this type as contact deposits, brought about by solutions circulating along the outer portions of the intrusions, and replacing or impregnating the gabbro, more or less, with ore. The conception is a time-honored one; it involves nothing unreasonable, and has the support of some of our ablest inves- tigators, as Emmons* and Posepny,^ but the objections to the igneous conception, it is fair to state, were not based on obser- vations of the phenomena, but on general theoretical considera- tions. ', G. F. Beoker, "Some Queries lii Rock Differentiation,'' Amer. Jour. Sci., January, 1897, 31. ' G. F. Becker, "Fractional Crystallization in Rocks," Idem, October, 1897, 257. ^ A very suggestive paper in this connection and one that has important applications to the Sudbury, Ont. ,'ores, is the following: "Segregation in Ores and Mattes," by David H. Browne,- School of Mines Quarterly, July, 1895, 297-311. * S. F. Emmons, "Geological Distribution. of the Useful Metals in the United States," Trans. Amer. Inst. Min. Eng., Chicago, 1893. Reprint pp. 18-19. ^ F. Posepny, "The Genesis of Ore Deposits," Idem. Reprint p. 194. 68 KEMP'S ORE DEPOSITS. 1.06.17. Under II. 1, the precipitating agencies are men- tioned, which are the chief causes in the chemical reactions of deposition, and these run through all the subterranean cavities as well. Their general application is esteemed self-evident. The large part played by organic matter, both when living and when dead and decaying, is notable. Its office, even in precipi- tating the gangue minerals in surface reactions, we are just be- ginning to appreciate. Siliceous sinters have been shown by W. H. Weed to be formed in the hot springs of the Yel- lowstone Park through the agency of algae, and A. Eothpletz has recently proved that the calcareous oolites around the Great Salt Lake are referable to minute organisms. Many accumulations of iron ores have, with reason, been attributed to the same agency ; but for this metal ordinary and common chemical reactions are oftenest applicable. When organic mat- ter decays, sulphurous gases are one of the commonest products, and likewise one of the most vigorous of precipitants. Thus, under Example 24, Pai'agraph 2.06.03, when speaking of the Wisconsin zinc and lead mines, it will be seen that such an agency from decaying seaweeds has been cited by both Whit- ney and Chamberlin. When the products of this decomposi- tion become imprisoned in the rocks as oils and gases, their ac- tion is unmistakably important and is especially available in limestones. Organic matter is a powerful reducing agent as well, and in' this way is capable of bringing down metallic compounds. The silver-bearing sandstones of southern Utah are cases in point, as they afford plant impressions now coated with argentite. The purely physical agencies cited under (d ) have also an important role. 1.06.18. Under 2(a) the uprising solutions may be di- verted by porous strata, so as to pass through them, and be subjected to precipitating agents of one kind or another. Porous beds furnish the simplest kind of cavities, and starting with these the scheme is developed in a crescendo to the most complicated. The purely chemical action of lindestone beds, however, seems at times to come into play and to cause precipitation along them. Of all rocks they are the most active chemical reagent. It may be questioned with reason as to whether caves or cav- erns (4), properly so called, have formed a resting-place for ores as often as some observers have supposed. So many CLASSIFICATION OF ORE DEPOSITS. 69 which have been cited as such may with greater reason be referred to shrunken replacements that each case should be clearly proven. 1.06.19. Under (5) brecciated beds, whose fragments are coated and whose interstices are filled with ore, are, with great reason, referred to the collapse from the removal of a support- ing layer. In addition to the illustration cited,the red hematite deposits of Dade and Crawford counties, Missouri, have been thought to have had a similar origin. Such phenomena are only to be expected in regions that have long been land. Cracks at the bends of folds may have occasioned, in eases, impregnations and disseminations, even when their character is obscured. The cracks need be but small and numerous to have produced far-reaching results. If a fault fissure, as a possible conduit of supply, crosses the axis of the fold, the nec- essary conditions are afforded for extended horizontal enrich- ment. Recent explorations with the diamond drill at Mine la Motte seem to corroborate such an hypothesis. Should the anticline or roll afterward sink toward the horizontal, a very puzzling deposit might originate. Shear zones have been al- ready discussed at length (1.03.03), as have true veins and volcanic necks (see also 3.09.20). As regards contact deposits, the igneous rock, which usually forms one wall, may serve two different purposes. It may act merely as an impervious bar- rier which directs solutions along its course, or serves to hold them, either because it is itself bent into a basin-like fold, or because it forms a trough with a dense bed dipping in an op- posite direction. Such relations occur in the Marquette and Gogebic ranges of the Lake Superior iron region. It is not apparent that in these cases the heat of the igneous rock has in any degree stimulated circulations. In the more characteristic "contact deposits" the igneous rock has apparently been a strong promoter of ore-bearing solutions, and has often been the source of the metals themselves. This form of deposit becomes, then, an attendant phenomenon, or even a variety, of contact meta- morphism. The classic illustration of it is furnished by the deposits of tin ore which have been especially developed along the con- tacts of granite intrusions. Granite, as is well-known, is the most' potent of all rocks in bringing about contact metamor- 70 KEMP'S ORE DEPOSITS. phism. It seems to be especially rich in mineralizers, and as its great, intruded, batholitic masses slowly crystallize, they emit boracic, hydrofluoric and other vapors in exceptional volume. Wall rocks are greatly corroded and charged with tourmaline, ■ fluorite, axinite, topaz, fluoric micas and cassiterite. Peg- matite dikes or veins are sent off as apophyses, and are charged with the same association of minerals. If the walls are them- selves granitic in composition, the feldspar becomes greatly corroded, and may be replaced by quartz and fluoric micas with more or less cassiterite. Pegmatites consisting essentially of the same minerals are also produced, and both varieties are called greisen, and are recognized as the characteristic gangue of tin ores the world over. The clue to the formation of the cassiterite in these surroundings was furnished bj' the early experiments of Daubree,' who volatilized the bichloride of tin and brought it into contact with steam in a tube, obtaining by double decomposition crystals of oxide of tin, identical in form writh the natural ones. In Nature, however, the fluoride of tin is the more probable source. The processes by which minerals and ores are emitted from igneous rocks, in the form of heated vapors, are often called pueumatolitic ; and if water also plays a part, pneumato-hj-datogenic. Under 11 chromite is the chief illustration. The mineral is practically limited to serpentinous rocks, and is distributed through them in irregular masses. It has been considered to be a product of alteration. 1.06.20. III. The debris that results from the weathering of rock masses under the action of frost, wind, rain, heat and cold, is washed along by the drainage system of a district, and the well-known sorting action transpires, which is so impor- tant in connection with the formation of the sedimentary rocks. Minerals of great specific gravity tend to concentrate by them- selves, while lighter materials are washed farther from the starting point, and settle only in still water. Stream bottoms supply the most favorable situations, and in their bars are found accumulations of the heavier minerals which are in the surrounding rocks. The commonest of these are magnetite, garnet, ilmenite, wolframite, zircon, topaz, spinel, etc., and with these, in some regions, native gold, platinum, iridosmine, etc.; ' Annales des Mines, XVI., 129. GLASSIFWATION OV ORE DEPOSITS. 71 in other places cassiterite, or stream tin, as described under tin. Even an extremely rare mineral, such as monazite, may make a sandbar of considerable size.^ The action of the surf or smaller shore waves is also a favorable agent. The throw of the breaker tends to cast the heavier material on the beach, where its greater specific gravity may hold it stationary. The heav- ier minerals may he sorted out of a great amount of beach sand. Magnetite sands, which have accumulated in this way, are of quite wide distribution, and at present are of some though not great importance. (Example 15.) With the mag- netite are found grains of garnet, hornblende, augite, etc., and often ilmenite. Gold is concentrated in the same way along the Pacific by the wash of surf against gravel cliffs. In aban- doned beaches of Lake Bonneville, near Fish Springs, Tooele County, Utah, placers of rolled bowlders of argentiferous ga- lena have been- worked. A superficial deposit of somewhat different origin is the bed of hematite fragments that mantles the flanks of Iron Moun- tain, Missouri, and runs underneath the Cambro-Silurian sand- stones and limestones. This seems to have been produced by the subaerial decay of the porphyry which formerly inclosed the ore. The heavier specular ore has thus been concentrated by its greater specific gravitj- and resistant powers.^ 1.06.21. There remain a few of great importance, but whose geological history is les6 clearly understood. They are nearl}- all involved in processes of regional metamorphism, and therefore in some of the most difficult problems of the science. Lenticular beds or veins of magnetite and pyrite that are inter- bedded with schists, slates, or gneisses are the principal group. Such magnetite bodies have been regarded as intruded dikes, as original bodies of bog ore in sediments, which have later be- come metamorphosed ; and as concentrated delta, river, or beach magnetite sands. It is possible that in instances they may be replaced bodies of limestone, afterward metamorphosed. The lenticular shape and the frequent overlapping arrangement of the feathering edges in the foot wall are striking phenomena. The overlap was referred by H. S. Munroe, in the School * See O. A. Derby, Amer. Jour. Set, III., xxxvii., p. 103. " See R. Pumpelly, "The Secular Disintegration of Rocks," Proe. Oeol. Soc. Amer., Vol II., December, 1890. 72 KEMP'S ORE DEPOSITS. of Mines Quarterly, Vol. III. , p. 34, to stream action during mechanical deposition, and a figure of some hematite lenses in the Marquette region was given in illustration. The arrange- ment in instances also suggests the shearing and buckling pro- cesses of dynamic metamorphism and disturbance. The individ- ual lenses, now in linear series," were thus all one original bed. The crumpling of the schistose rocks has pinched them by small buckling folds and shoved the ends slightly past each other in the process so familiar in the production of reversed faults from monoclines. Sheared granitic veins on a small scale are a not uncommon thing in areas of schistose rocks, such as Manhattan Island, in the city limits of New York, and suggest strongly this explanation. Should the compression not go so far as to bring rupture of the bed, but only a thickening by the formation of a sigmoid fold, it would occasion an en- larged cross section, as has been suggested by«B. T. Putnam' for the great magnetite ore body at Mine 21, Mineville, in the Lake Champlain region. 1.06.22. Quartz veins, often auriferous and of a lenticular character, furnish another puzzling ore body. They are com- monly called segregated veins, and lie interfoliated in slates or schistose rocks. If in a pre-existing cavity, the cavity must have been formed, either by the opening of beds under compres- sion, or by displacement along the bedding, so that depressions came opposite each other Replaced lenses of limestone which had been squeezed into this shape from an original, connected bed should also be instanced as a possibility. But notwithstanding the time-honored nature of the conception of these "segregated" veins, there is little doubt that they are practically all mere varieties of fissure veins, which have been pinched into the separated lenses by pressure, 1.06.23. The veins that contain cassiterite in many parts of the world, and that yet have the mineralogical composition of granite, are another product of metamorphic action, both con- tact and regional. The gangue minerals, feldspar, quartz, and mica, are quite characteristic of acid, igneous rocks, but the coarseness of the crystallization in the comparativelj' nar- row veins bars out a normal igneous form of origin. All our artificial methods of reproducing these minerals lead us to ' Tenth Census, Vol. XV., 110. GLASaiFICATION OF ORE DEPOSITS. 73 infer that the veins were filled at a high temperature and pres- sure, therefore at considerable depths, and through the aid of steam. Cassiterite has also been detected in a few rare cases, under such circumstances that it seemed to be an original min- eral in igneous granite. It is probable, therefore, that it may in instances be an original and early crystallization from an igneous magma, much as is magnetite. More observed cases would be welcome as evidence. 1.06.24. Fahlbands should be mentioned here. The term refers to belts of schists, which are impregnated with sulphides, but not in sufficient amount in the locality where the name was first applied (Kongsberg, Norway) to be available for ores. The decomposition of the sulphides gave the schists a rusty or rotten appearance that suggested the name. Whether the ores are an introduction into the schist, subsequent to metamorphism, or a deposit in and with the original sediment, is a doubtful point. The practical importance of these fahlbands lies in the enriching'influence that they exert on the small fissure veins that cross them. 1.06.25. The phraseology of the above schemes will be em- ployed in the subsequent descriptions. In addition, much em- phasis will be placed on the character of the rocks containing the deposits, whether unaltered sedimentary, igneous, or meta- morphic, and whether in the first and last cases igneous rocks are near, for these considerations enter most largely into ques- tions of origin. The ore deposits are illustrated by examples, somewhat as has been done by one of the best of modern writers abroad. Von Groddeck. The word "example" is preferred to "type," which was employed by Von Groddeck, because it im- plies less of an individual character. We may cite deposits under different metals thus which all might belong to one type. Under each metal will be given, first, a list of general treatises and papers. These will be marked "Hist." when especially valuable as history, and "Eec." when recommended for ordi- nary examination. If not marked by either, they are more adapted for special investigations. y^ KEMP'S ORE DEPOSITS. GENERAL REFERENCES ON ORE DEPOSITS. Adams, F. D. "On the Igneous Origin of Certain Ore Depos- its," General Mining Association of the Province of Quebec, January, 1894. Ansted, D. T. "On Some Eemarkable Quartz Veins," Quar. Jour. Geol. Sci., XIII., 346. Barus, Carl. "The Electrical Activity of Ore Bodies," Trans. Amer. Inst. Min. Eng., XIII., 417. (See also Becker's Monograph on the Comstock Lode, p. 310, for refer- ences to other papers. ) Becker, G. F. "The Relations of the Mineral Belts of the Pa- cific Slope to the Great Upheavals," J.mer. Jour. Sci., III., 38, 309, 1884. Belt, Th. "Mineral Veins; an Inquiry into their Origin, founded on a Study of the Auriferous Quartz Veins of Australia," London, 1861. Bischof, G. "On the Origin of Quartz and" Metalliferous Veins," Jameson's Journal, April, 1845, p. 344. Ab- stract, Amer. Jour, Sci., I., 49, 396. Advocates aque- ous deposition. Brown, A. J. "Formation of Fissures and the Origin of their Mineral Contents," Trans. Amer. Inst. Min. Eng., II., 315. Bulkley, F. G. "The Separation of Strata in Folding," Idem, XIII., 384. Campbell, A. C. "Ore Deposits," Engineering and Mining Journal, July 17, 1880, p. 39. Cotta-Prime von. "Ore Deposits." German, by Von Cotta, 1859; English translation by Prime, 1870. Rec. Crosby, W. O. "A Classification of Economic Geological De- posits based on Origin and Original Structure," Amer, Geologist, April, 1894, p. 349. Rec. Cumenge, E., et Robellaz, F. L'Or dans la Nature. Paris, 1898. (Being issued in parts, 1899.) Daubree, G. A. Etudes synthetiques de Geologic experimentale Paris, 1879. CLASSIFICATION OF ORE DEPOSITS. 75 Daubree, G. A. Lea Eaux souterraines aiix Epoques anciennes. Paris, 1887. Les Eaux souterraines a I'Epoque actuelle. 2 vols. Paris, 1887. De Launay, L. Contribution 4 1'Etude des Gites Metallifdres, Annates des Mines, August, 1897. Emmons, E. American Geology, 134, 1853. General dis- cussion. Emmons, S. F. "The Structural Eolations of Ore Deposits," Trans. Amer. Inst. Min. Eng., XVI., 304. Eec. "Notes on Some Colorado Ore Deposits," Proc. Colo. Sci. Sac, II., Part II., p. 35. "On the Origin of Fissure Veins," Proc. Colo. Sci. Soc, II., p. 189. Eec. (See also E. C. Hills, Idem, III., p. 177.) "The Genesis of Certain Ore Deposits," Trans. Amer. Inst. Min. Eng., XV., 125. Eec. "Geological Distribution of the Useful Metals in the United States," Trans. Amer. Inst. Min, Eng., XXII., 52. Eec. Endlich, F. M. Hayden's Survey, 1873, p. 276. General de-, scription of veins. Fairbanks, H. W. "The Eolation between Ore Deposits and their Enclosing Walls," Engineering and Mining Journal, March 4, 1893, p. 200. Foster, C. L. "What is a Mineral Vein?" Abstract in Oeol. Mag., Vol. I., 513. Fuchs, E., et De Launay, L. Traite des Gites Mineraux et Metalliferes. Paris, 1893. Eec. Fox, E. W. "Formation of Metallic Veins by Galvanic Agency," Amer. Jour. Sci., I., 37, 199. Abstract from London and Edinburgh Phil. Mag., January, 1839. "On the Electro-Magnetic Properties of Metalliferous Veins in the Mines of Cornwall," Amer. Jour. Sci., I., 20, 136. Abstraict of paper before the Eoyal Society. Glenn, W. "The Form of Fissure Walls, as Afifected by Sub- Fissuring and by the Flow of Eocks," Trans. Amer. Inst. Min. Eng., XXV., 499, 1895. Grimm, J. "Die Lagerstatten der Nutzbaren Mineralien," 1869. 76 KEMP'S ORE DEPOSITS. Groddeck, A. von. "The Classification of Ore Deposits," Engineering and Mining Journal, June 37, 1885, p. 437. "Die Lehre von den Lagerstatten der Erze," 1879. Rec. (See also Engineering and Mining Journal, Jan. 3, 1880, p. 3, for a review of same.) Hague, A. D. "Mining Industries, Paris Exposition, 1878." Henrich, C. "On Faults," Engineering and Mining Jour- nal, Aug. 24, 1889, p. 158. Hunt, T. S. "The Geognostical History of the Metals, Trans. Amer. Inst. Min. Eng., I., .331. "The Origin of Metalliferous Deposits," in Chemical and Geological Essays. "Contributions to the Chemistry of Natural Waters," Amer. Jour. Sic, II., 39, 176. Julien, A. A. "On the Part Played by Humus Acids in Ore Deposit, Wall Rock, Gossan," etc., Proc. Amer. Assoc. Adv. Sic, 1879, pp. 383, 385. Keck, R. "The Genesis of Ore Deposits," Engineering and Mining Journal, Jan. 6, 1883, p. 3. "Revievi^ of Ore Deposits in Various Countries." Denver, 1893. 31 pages. Kemp, J. F. "A Brief Review of the Literature on Ore De- posits," School of Mines Quarterly, X , 64, 116, 336; XL, 359 ; XIL, 219. "On the Filling of Mineral Veins," School of Mines Quarterly, October, 1891. "The Classification of Ore Deposits," School of Mines Quarterly, November, 1892. "On the Precipitation of Metallic Sulphides by Natural Gas," Engineering and Mining Journal, December, 1890. "An Outline of the Views Held To-day on the Origin of Ores," The Mineral Industry, IV., 755, 1895. Kimball, J. P. "Our Mineral Interests," Memoirs of the American Bureau of Mines. Kleinschmidt, J. L. "Gedanken ueber Erzvorkommen, " Berg- und Huet Zeit., 1887, p. 413. Koehler, G. "Die Storungen der Gange, Flotze, u. Lager," Leipzig, 1886. Translated by W. B. Phillips under CLASSIFICATION OF ORE DEPOSITS. 77 title of "Irregularities of Lodes, Veins and Beds," Engineering and Mining Journal, June 25, 1887, p. 454; also July 2, p. 4. Leconte, J. "Mineral Vein Formation in Progress at Steam- boat Springs, compared with the same at Sulphur Bank," Amer. Jour. Sci., III., 25, 424. "Genesis of Metalliferous Veins," Amer. Jour. Sci., July, 1883. See other references under "Mercury." Leconte, J., and Rising, W. B. "The Phenomena of Metalli- ferous Vein Formation now in Progress at Sulphur Bank, Cal." Amer. Jour. Sci., July, 1882, p. 23. Moreau, George. "Etude Industrielle des Gites Metalli- feres," Paris, 1894. Rec. Miiller, A. Erzgange. Basel, 1880. Munroe, H. S. "List of Books on Mining," School of Mines Quarterly, X., 176. Necker. "On the Sublimation Theory," Proc. Geol. Soc. of London, Vol. I., p. 392; also Ansted's Treatise on Ge- ology, Vol. II., p. 271. Hist. Newberry, J. S. "The Origin and Classification of Ore De- posits," School of Mines Quarterly, I., March, 1880; Engineering and Mining Journal, June It) and July 23, 1880; Proc. Amer. Assoc. Adv. Sci., \o]. XXXIL, p. 243, 1883. Rec. "The Deposition of Ores," School of Mines Quarterly, v., 329, 1884; Engineering and Mining Journal, July 19, 1884. "Genesis of Our Iron Ores," School of Mines Quarterly, II., 1, 1880; Engineering and Mining Journal, April 23, 1881. See also under "Iron." "Genesis and Distribution of Gold," School of Mines Quarterly, III., 1881; Engineering and Mining Jour nal, Dec. 24 and 31, 1881. Rec. Oohsenius, Carl. "Metalliferous Ore Deposits," Geol. Mag., L, 310. Hist. Pearce, Rich. "On Replacement of Walls," Chem. News, March 3, 1865. Penrose, R. A. F. "The Superficial Alteration of Ore Depos- its," Journal of Geology, II., 288, 1894. Rec. 78 KEMP'S ORE DEPOSITS. Phillips, J. A. "The Rocks of the Mining District of Corn- wall and their Relations to Metalliferous Deposits," Quar. Jour. (Jeol. Soc, XXXI., 319. "A Contribution to the History of Mineral Veins," Quar. Jour. Geol. Soc, XXXV., 390. "Connexion of Certain Phenomena with the Origin of Mineral Veins," Phila. Mgazine, December, 1871. "Treatise on Ore Deposits," London, 1884. Posepny, F. Archiv fiir praktische Geologie, I. and II. "The Genesis of Ore Deposits," Trans. Ainer. Inst. Min. Eng., XXIL, 63. Rec. Power, F. D. "The Classification of Valuable Mineral De- posits," Trans. Australasian Inst. Min. Eng., 1892. Pumpelly, R. Johnson's Encycl., Vol. VI., p. 32. Rec. Raymond, R. W. "What is a Pipe Vein?" Engineering and Mining Journal, Nov. 23, 1878, p. 361. Translation of Lottner, and general remarks on Classi- fication, Min. Stat. West of Rocky Mountains, 1870, p. 447. Indicative Plants, Trans. Amer. Inst. Min. Eng., XV., 645. "Geographical Distribution of Mining Districts in the United States," Idem, I., p. 33. Rickard, T. A. "Vein-Walls," Trans. Amer. Inst. Min. Eng., XXVL, 193, 1896. Sandberger, F. "Untersuchungen liber Erzgange," 1882; "Theories of the Formation of Mineral Veins," Engi- neering and Mining Journal, March 15, 22, 29, 1884, pp. 197, 212, 232. "Untersuchungen an den Erzgangen von Pribram in Boh- men," Sitzungsber. der Wurzburger Phys. Med, Ge- sellschaft, 1886. Neue Beweise fiir die Abstammung der Erze aus dem Nebengestein, Idem, 1883. Stelzner, A. W. "Die Lateralsecretions-Theorie und ihre Be- deutung fiir das Pribramer Ganggebiet," B. and H. Jahrbuch der K. K. Bergakademie zu Leoben, XXXVII. Tarr, R S. "The Economic Geology of the United States," 1894. CLASSIFICATION OF ORE DEPOSITS. 79 Vogt, J. H. L. "Bildung von Ezlagerstatten durch Differen- tiationsprocesse in basischen Eruptivmagmata, " Zeit- sclirift f. praktische Geologic, 1893, pp. 4, 143, 257. Eec. "Ueber die Kieslagerstatten vom Typus Roros," etc., Idem, 1896, pp. 41, 117, 173. Rec. "The Formation of Eruptive Ore Deposits," The Min- eral Industry, IV., 1895, pp. 743, 754. Rec. "Ueber die relative Verbreitung der Elemente, besonders der Schwermetalle, und ueber die Concentration der fein vertheilten Metallgehaltes zu Erzlagerstatten, " Zeit- schrift fUr prakt. Geologie, August, 1898, to January, 1899, and later. Rec. Wabner, R. "Ueber die Eintheilung der Minerallagerstatten nach ihrer Gestalt, sowie die Anwendung und die Be- niitzung der Worte, Lager und Flotz," Berg- und Huet. Zeit., Jan. 2, 1891, p. 1. Wadsveorth, M. E. "The Theories of Ore Deposits," Proc Boston Soc. Nat. Hist., 1884, p. 197. Rec. "The Lateral Secretion Theorj' of Ore Deposits," Engi- neering and Mining Journal, May 17, 1884, p. 364. "Classification of Ore Deposits," Rep. of Mich. State Geologist, 1891-92, p. 144. Rec. Whitney, J. D. "Remarks on the Changes vrhich take place in the Structure and Composition of Mineral Veins near the Surface," Amer. Jour. Sci., ii. XX., 53. "Metallic Wealth of the United States," 1854. Rec. Whittlesey, C. "On the Origin of Mineral Veins," Proc. Amer. Assoc. Adv. Sci., XXV., 213. Williams, Albert. "Popular Fallacies Regarding the Pre- cious Metal Ore Deposits," Fourth Ann. Rep, Director U. S. Geol. Survey, pp. 257-278. PART II. THE ORE DEPOSITS. CHAPTER I. THE IRON SERIES (iN PART)— INTRODUCTORY REMARKS ON IRON ORES — LIMONITE — SIDERITB. GENERAL LITERATURE. Birkinbiae, J. "Prominent Sources of Iron Ore Supply,'' Trans. Amer. Inst. Min. Eng., XVII., 715. Statis- tical; Rec. "The Production of Iron Ores in Various Parts of the World." Sixteenth Ann. Rep. Dir. U. S. Geol. Survey. Part III., 21. Rec. Chester, A. H. "On the Percentage of Iron in Certain Ores," Trans. Amer. Inst. Min. Eng., IV., 219. Dunnington, F. P. "Ou the Formation of the Deposits of Oxides of Manganese," Amer. Jour. Sci., iii,, XXXVL, 175. The paper treats of Iron also. Hewitt, A. S. "Iron and Labor," Trans. Amer. Inst. Min. Eng., XVIII. The paper contains valuable statistics. "A Century of Metallurgy," Idem, V., 164. Hunt, T. S. "The Iron Ores of the United States," Idem, XIX, 3. Kimball, J. P. "Genesis of Iron Ores by Isomorphous and Pseudomorphous Replacement of Limestone," Amer. Jour. Sci., September, 1891, p. 231. Continued in Ainer. Geologist, December, 1891. Julian, A. A. "The Genesis of the Crystalline Iron Ores," Trans. Phil. Acad. Nat. Sci., 1882, p. 335; Engineer- ing and Mining Journal, Feb. 2, 1884. "Origin of the Crystalline Iron Ores," Trans. N. Y. Acad. Sci., II., p. 6; Amer. Jour. Sci., iii. XXV., 476. Lesley, J. P. "The Iron Manufacturers' Guide," 1866. Hist. Rec. Newberry, J. S. International Review, November and De- cember, 1874. "Genesis of the Ores of Iron," School of Mines Quar- 84 KEMP'S ORE DEPOSITS. terly. November, 1880. Rec. Anier. Jour. Sci., iii., XXI^, 80. "Genesis of the Crystalline -Iron Ores," Trans. N. Y. Acad. Sci., II., October, 1883. Rec. Newton, H. "The Ores of Iron: Their Distribution with Ref- erence to Industrial Centers," Trans. Amer. Inst. Min. Eng., III., 360. Pumpelly, R., and Others. Tenth Census, Vol. XV., 1886, es- pecially pp. 3-17. Rec. Reyer, E. "Geologie des Eisens," Oest. Zeii. f. B. undH., 1882, Vol. XXX., pp. 89, 109. Rogers, W. B. "On the Origin and Accumulation of the Pro- tocarbonate of Iron in the Coal Measures," Proc. Bos- ton Sac. Nat. His., 1856. Smock, J. C. "On the Geological Distribution of the Ores of Iron," Trans. Amer. Inst. Min. Eng., XII., 130. "Iron Mines and Iron Ore Districts in New York," Bull. N. Y. State Mu,seum, June, 1889. Rec. Swank, J. M. Chapters on Iron in Mineral Resources, U. S. Geol. Survey, since 1883. "History of the Manufacture of Iron in All Ages." 1891. Whitney, J. D. '.'Metallic Wealth of the United States," 1864, p. 425.' Hist. "On the Occurrence of Iron in the Azoic System," Proc. Amer. Assoc. Adv. Sci., 1855, 209; Amer. Jour. Sci., ii. XXII. , 38. Winchell, N. H. and H. V. "The Iron Ores of Minnesota," Bull. No. 6, Minn. Geol. Survey, 1891. Part IV, contains an exhaustive review of methods of origin, and Part V. a very complete annotated bibliography. Table of the Iron Ores, Limonite, Siderite, Hematite, Magnetite, Pyrite. Fe. HjO. CO2. S. Limonite (brown hematite, bog ore), SFejOs 3H3O 59.89 U4 Siderite (Spathic ore, clay-ironstone, black- . band) FeCO, Hematite (red and specular), FeaOj Magnetite, FeO, FejOs, or Fe.Oi . . . 48.27 TO.O 72.4 46.7 37.92 Pyrite, FeSj 53.3 THE IRON SERIES {IN PART). 85 2.01.01. No one of the iron ores ever occurs pure in large amounts. Only a few closely approach this condition. The largest quantity of rich ore as yet mined in the United States '.vas doubtless obtained from the Lovers' Pit opening, oper- ated bj' Witherbee, Sherman & Co., on Barton Hill, near Mineville, N. Y. The pit yielded 40,000 tons of magnetite that averaged 68. 6% Fe, with many carloads at 73%'. The micaceous specular of the Republic mine, Mich., is said to have been shipped an entire season at 69%. The Min- nesota mines, near Tower, Minn., have cleared many cargoes at 68 to 68.4%. The richest are the magnetites and specular hematites, and many mines of the Lake Cham- plain district have produced the former, and Lake Superior mines the latter, at 63 to 65%, or even more. The separated ores in the Lake Champlain district run about ('>.i%. The unseparated ores have much less, and indeed all percentages from 60 to 65. Thus the lump ore (shipped as mined) from Chateaugay, N. Y., has about 50%. The Cornwall (Pa.) magnetite holds even less. The Clinton red hematites from Xew York afford about 44% in the furnace, as the result of long experience. The limonites, as usually mined, produce from 40 to 50%. The crude spathic ores are the lowest of all, and in the variety black-band may even be about 30%. They are easily calcined, however, and on losing their carbonic acid, moisture and bituminous matter the percentage of iron rises a third or more. A. H. Chester found in 1875, as the result of an endeavor to determine the average yield of certain standard ores in the furnace. Lake Superior specular, 62.5%; Lake Superior limonite, 49.5%, which is much too low to be sala- ble to-day; Rossie (N. Y.) red hematite, 54.5%; Wayne County (N. Y.) Clinton ore, 40%. 2.01.02, The common impurities in iron ores are the com- mon elements or oxides that enter most largely into rocks, and those which make up the walls of the deposit are usually the ones that appear most abundantly in the ore. Silica (Si02), alu- mina (AI2O3), lime (CaO), magnesia (MgO), titanium oxide (TiOa), carbonic acid (CO2), and water (H2O) appear in large amounts and determine to a great extent the character, fluxing properties, -etc., of the ore. With these, and of more far-reach- ing influence, are smaller amounts of sulphur and phosphorus. 86 KEMP'S OBE DEPOSITS. The last two and titanium chiefly determine the character of the iron which is yielded in the furnace, and are the first foreign ingredients sought by analysis. The sulphur is present in pyrite. the phosphorus in apatite. As is well known, 0. 1%" of phosphorus is set as the extreme limit for Bessemer pig irons, and as ores for these command the best market, they are eagerly sought. To obtain the allowable limit of phosphorus in the ore, its per- centage in iron is divided by 1000. Thus a 65.3% ore should not have over 0.065% phosphorus to be ranked as Bessemer. If at the same time, with sufficiently low phosphorus, the gangue in highly siliceous, a composition desirable for Bessemer prac- tice, ores have been of value, although of comparatively low grade, and remotely situated. For Lake Superior ores the buyers insist to-day on a still lower Bessemer limit, and do not call any ore over 0. 05% phosphorus a strictly Bessemer ore. The ore is required to be low enough to carry the phosphorus in both fuel and flux, and still yield a pig iron of not over 0.1% P. On the other hand a moderate amount of phosphorus is not only no drawback for ordinary foundrj' irons, and such as are subjected to tool treatment, but is a prime necessity. Excessive amounts are desired onlj' for weak but very fluid irons or for the basic steel process. Considerations like these, which are rather metallurgical than geological, largely determine the availability of a deposit, and to some extent the present loca- tions of the mining districts. 3.01.03. Iron itself is one of the most abundant and widely disseminated elements entering into the composition of the earth. Several writers have attempted to deduce the general composition of the outer portions of the globe,' but the most reliable computation is that of F. W. Clarke in Bulletin 78 of the U. 8. Geol. Sum., pp. 34-43. The crust to a depth of ten miles below sea-level is the subject of the estimate, and the air and ocean are included. The composition of the solid crust is reached by averaging analj'ses of igneous and crystalline rocks, 880 in all ; 331 from the United States, 75 from Europe, and 486 from all quarters. Igneous rocks, being the ultimate source of the others, furnish a good average. The final result ' Compare Alex. Winohell, Oeological Studies, pp. 19-20, and Prest- wich's Geology, I. p. 10— both of which were quoted in the first edition of this work. THE IRON SERIES {IN PART). 87 is the following, in which amounts less than 0.01% are omitted. The total is 100. .....49.98 >fa. .,..2.38 P 0.09 Si 25.30 K.. . . . .3.23 Mn..,.. 0.07 Al 7.26 H. ,....0.94 S , 0.04 Fe..... ..... 5.08 Ti. C. .....0.80 ....0.31 Ba. . . . . , N....... , . 0.03 Ca 3.51 0.02 Mg..... 2.50 CI. Br. . . . ....0.15 Cr 0.01 From this it is seen that iron is much the most abundant of the useful metals, and that its common impurities, titanium, phosphorus and sulphur are all present in appreciable amounts. S.Ol.Oi. A general comparison of tabulated analyses of igneous rocks (Roth's Gesteinsanalysen and Allgemeine Geologie) shows that granites contain 0.0-7% iron oxides, por- phyries 0.0-14%, rhyolites, 0.0-8%, diorites and diabases 4-16%, andesites 3-15%, basalts 13-20%. Limestones invariably have at least small amounts, and at times very considerable percent- ages. Sandstones are often low, but not seldom are stained through and through. The metamorphic rocks offer close analogies to the igneous. In general distribution and in quan- tity, iron leads the list of the distinctively metallic elements. Its peculiar property of possessing two oxides, of different chemical quantivalence, assists greatly in the formation of ores and the general circulation of the metal. This is set forth under the following examples : LIMONITE. 3.01.05. Example 1. Bog Ore. — Beds of limonite, super- ficially formed in marshes, swamps, and pools of standing water. The general circulation of water through the rocks enables it very frequently to take up iron in solution. Ferru- ginous minerals are among the first and easiest that fall a prey ' to alteration. Carbonic acid in the water aids in dissolving the iron, which thvis, in waters containing an excess of CO2, passes into solution as the protocarbonate FeCOs. Organic acids may also play a part. The alteration of pyrite affords sulphuric acid and ferrous sulphate, and the latter enters readily into solution. On meeting calcium carbonate, both ferric and fer- rous sulphate are decomposed, yielding in the first case calcium sulphate, ferric hydrate, and carbonic acid; in the second, if 88 KEMP'S ORE DEPOSITS. THE IRON SERIEa {IN PART). 89 air is absent, ferrous carbonate and calcium sulphate, but on the admission of air, ferric hydrate soon forms.' 2.01.06. Bodies of limonite that become exposed to a reduc- ing action from the favorable presence of decaying organic matter likewise furnish the protocarbonate. In general it may be stated that free oxygen must be absent or present only in small quantity where solution takes place. Sooner or later the ferruginous (or chalybeate) waters come to rest, especiallj^ in swamps. The protosalt is exposed to the evaporation of the excess of CO2, that held it in solution, and also to the action of oxygen. Two molecules of carbonate, together with one atom of oxygen and some water, break up into CO2, and the hy- drated oxide 3 FcaOs, 3 H2O, or some related molecule. The latter forms as a scum and then sinks to the bottom and accu- mulates in cellular masses. The sesquioxide is insolul)le, and as against ordinary waters free from reducing agents it remains intact. Deposits of mud and peat forming above may cover the beds with a protecting layer. Hardly a bog exists which does not show, when cut in cross section, the bog ore beneath. Frequent associates of the ore are diatomaceous earth and shell marl, contributed by the remains of organisms which once inhabited the waters. At times excellent impres- sions of leaves and shells are preserved in the ore. Such ore bodies are not often practicably available on account of the low percentage in iron, due to the abundance of sand and silt washed in, and to the frequent large amounts of sulphur and phosphorus which they contain. The sulphur is present in pyrite and the phosphoras in vivianite, sometimes in sufficient quan- tity to be visible as at Mullica Hill, N. J., where the variety Mullicite is found. lu certain parts of the country bog deposits have been utilized and under peculiar conditions others maj' yet be. 2.01.07. In eastern North Carolina bog-ore beds are fre- quent and are found lying just below the grass roots. Scat- tered nodules occur in the overlying soil, which are succeeded by a bed three feet or less in thickness, resting on sand.^ ' F. P. Dunnington, Amer. Jour. Set., iii., XXXVI., 176. Experiments 10 and 11. " W. C. Kerr, Oeology of North Carolina, 1875. p. 218. B. Willis, Tenth Census, Vol. XV., p. 302. H. B. C. Nitze, Bull. I. N. 0. Geol Survey, 1893. 90 KEMP'S ORE DEPOSITS. In Hall's Valley and Handcart Gulch, Park County, Colo., interesting and extensive deposits of limonite are in ac- tive process of formation. The iron comes from neighboring great beds of pyrite.' Bog ore of good quality has recently been reported from the vicinity of Great Falls, Mont.^ At Port Townsend Bay, in the vicinity of Puget Sound, and at the Patton mines, near Portland, Ore. , the ores are of such quality as to be available.' Attention has been lately directed to the great deposits of bog ore in the Three Rivers district of the Province of Quebec in Canada. Three Eivers is on the St. Lawrence about midway between Montreal and Quebec, but the district which furnishes the bog ores extends from northeast of Quebec to a point west of Ottawa, an area stated by Griffin to be 400 miles long by •±0 to 60 broad. The drainage of the old Archean height's of the Laurentides, the range that suggested the name Laurentian, crosses the belt, and being more or less laden with ferruginous solutions it deposits the ore in swamj)s, streams and lakes, wherever the water is for a time stationary or choked with vegetation. The ore beds furnish ideal illustrations of bog-ore deposits in all their forms. Beginning as a light filno, the ore gradually accumulates on the bottom, where it hardens into thick crusts. These are exposed to the sun in the dry season in the shallower reaches, and become very hard cakes. Dur- ing the succeeding wet season they are buried again under more ore, or sand and ore, until the thickness attained is very considerable. The ore is precipitated also in running ■\yater, and has been obtained from ravines in goodly amount. Even in the pipes used at the furnace at Radnor Forges for conveying the necessary water supply from the neighboring Riviere au Lard, the limonite deposits. The river flows from the swamp called Grand Pie, in the midst of which is a shallow lake called Lac a la Tortue. Ore is dug in the swamp and dredged in the lake. The ' R, Chauvenet, " The Iron Resources of Colorado," Trans. Amer. Inst. Min. Eng., XVIII., 266. "Notes on Iron Prospects in Northern Colo- rado," Ann. Rep. Colo.School of Mines, 1886. ' Mineral Resources, U. 8. Oeol. Survey, 1888, p. 34. 3 B. T. Putnam, Tenth Census, Vol. XV., p. 496. THE IRON SERIES (IW PART). 91 supply is renewed after being removed. The deposits present many analogies with those of the Swedish lakes, later men- tioned, but they supply caked ore rather than the oolitic form of the latter. The iron industry began in the region in 1730 and has continued more or less intermittently to date.^ The iron furnished has especial excellence for car-wheels and chilled castings. The lake ores seem to run somewhat richer than those of the bogs. The latter contain about 42. 5% Fe, the former 49%. Both have a little over 0.3% P and less than 0.1%" S, These ore bodies are of great scientific interest, for they illustrate (as has been recognized for many years) the formation of bodies of other kinds of iron ores when in sedimentary series, and even when metamorphosed. Ore 6-15 Fig. 8. — Cross-section of the Prosser iron mine, near Portland, Ore., shoiving the bed of limonite between two sheets of basalt. After B. T. Putnam, Tenth Census, Vol. XV., p. 49fi. 2.01.08. A somewhat different varietj' of Example 1 results when the ferruginous waters come to rest in the superficial hol- lows of the rock which has furnished the iron. Depressions in the serpentines of Staten Island, N. Y., contain such deposits, and the ore has been referred by N. L. Britton to the leaching of the underlying rock. It contains a notable percentage of chromium, which is known to be an element in the serpentine. The mines have been in former years quite large producers. Similar limonites occur at Rj'e, N. Y.^ ' See especially, P. H. Griffin, " The Manufacture of Charcoal-iron from the Bog and Lake-ores of the Three Rivers District," Trans. Amer. Inst. Min. Eng., XXI., 974, Also J. H. Bartlett, Trans. Amer. Inst. Min. Eng., XIV., 508. ^ N. L. Britton, School of Mines Quarterly, May, 1881. Compare also .4mer. Jour. ScL, iii., XX., 32, and XXII.. 488. 92 . KEMP'S ORE DEPOSITS. At the Prosser mines, cear Portland, Ore., deposits of limo- nite are found in the superficial hollows of a Tertiary basalt of the Cascade range. The ore contains roots and trunks of trees, and is coveied by a later flow of basalt. Similar bodies of limonite resulting from basalt are known in the German prov- ince of Hesse, and in Ireland.' 2.01.09. The limonite sand, or oolite, that forms in the Swedish lakes about ten meters from the banks and in water up to ten meters in depth is another variety of this type. A layer half a meter and less in thickness accumulates every fifteen to thirty years, and is periodically dredged out. The ore is precipi- tated first as a slime that breaks up afterward into small con- cretions. It has been thought that the formation of these and similar bodies of limonite has been aided by small algae and other plants or microscopic organisms.^ 2"01.10. Example 2. Bodies of limonite in cavities of fer- ruginous rocks, on the outcrop, or below the surface, which have resulted either from the alteration of the rock in situ or from its partial replacement by limonite. Residual clay, quartz and other remains of alteration usually occur with the ore. Ferruginous limestones are the commonest sources of such deposits, but other rocks may afford them. The deposits are not limited to any one geological series, but in different parts of the country occur wherever the conditions have been favorable. Some of the ore may have been brought in by sub- terranean circulations which have leached the neighboring rocks. Considerable limonite has also resulted from the weath- ering of clay- ironstone nodules and black-band beds in the ■ B. T. Putnam, Tenth Census, Vol. XV.. p. 16, and J. S. Diller, "A Geological Reconnaissance in Northwestern Oregon," Eighteenth Ann. Rep. U. S. Oeol. Survey, Part II., on the Oregon ore; Tasche, Berg.- und Hutt. Zeit, 1886, p. 209; also Wurtemberger, Neues Jahrb., 1867, p. 685, on the Hessian ores; Tate and Holden, "On the Iron Ores Associated with the Basalt of Northeastern Ireland," Quar. Jour. Geol. Soc, XXVI., 151. " F. M. Stapflf, Zeitschr. d. d. geolog. Gesellsch., 1866, Vol. XVIII., p. 8, on the geology of the ores. Sjogrun, Berg.- und Hutt. Zeit., 1865, p. 116, on the agency of algae. On the general formation of bog ores the follow- ing papers are of interest : G. J. Brush and C. S. Rodman, ' ' Observations on the Natives Hydrates of Iron," Amer. Jour. Sci., ii., XLIV., 219; J. S. Newberry, School of Mines Quarterly, November, 1880; J. Roth, Chem. und Phys. Oeologie, I., pp. 58, 97, 221; F. Senft, Humus, Marsch, Torf und Limonit-bildungen. THE IRON SERIES {IN PART). 93 Carboniferous system (to be mentioBed later), and not infre- quently from the alteration of nodular masses of pyrites. The limonite is in cellular lumps, in pipes, pots, and various imi- tative forms vs^hich often have a beautiful lustre. The hollow masses have in general resulted from the filling of reticulated cracks in shattered roOk. The ore thus deposits around the cores of country rock, vs^hich afterward are removed, leaving a hollow shell, or geode. (See Tenth Census, Vol. XV., pp. 275, 369, 370.) Fig. 9. — Section of the Hiirst limonite bank, Wythe County, Virginia, illustrating the replacement of shattered limestone mth limonite and the formation of geodes of ore. After E. R. Benton, I'enth Census, Vol. XV., p. 275. 3.01.11. Reserving the Siluro-Cambrian limonitesfor a sub- type the ore bodies are described in order from east to west, taking up first the Allegheny region, then the Mississippi Val- ley, and lastly the Rocky Mountains. The limonites of New England and New York belong to the present subtype, as do those of eastern Pennsylvania and the more important ones in Virginia, Tennessee, Georgia and Alabama. In central and western Pennsylvania, however, not a small amount is obtained from the higher lying terranes. The Hudson River slates fur- nish small amounts in Franklin County, which are thought by McCreath to have resulted from the alteration of nodules of 94 KEMP'S ORE DEPOSITS. pyrites/ The Medina sandstones contain highly ferruginous portions in Huntingdon County.^ The lower Helderberg and Oriskany are locally quite productive in Blair County, affording several great banks of ore.' The Oriskany is of greater importance in Virginia than in Pennsylvania. East of these last-mentioned exposures, and in southern Carbon County, in a bed of paint ore between the Oriskany and the Marcellus/ The Marcellus is the most productive of the Devonian stages. It affords considerable ore in Perry County,' Juniata County, Mifflin County, Huntingdon County.' Fulton County' and Franklin County.' All these are in southern Pennsylvania. Lesley states' that the ore is weathered carbonate. As shown under Example 4, beds of carbonate ore occur in Ulster County, New York, in the Marcellus. (Addi- tional details on the above Pennsylvania deposits will be found in the geological reports on the particular counties.) 2.01.13. As already remarked, the greater part of the limon- ites in Virginia belong under the Siluro-Cambrian division and are there described, but in the James Eiver Basin, on Pur- gatory and May's Mountains, there are deposits in sandstones of the Clinton.^" Other limonite beds^ occur in the Oriskany on Brushy Mountain (Longdale mines), on Rich Patch Mountain (Low Moor mines, called by Lyman, Marcellus), on Warm Spring Mountain, and on Peter Mountain. In the Shenandoah Valley, on Massanutton Mountain, the limonite is referred by Prime to the Clinton stage." On North Mountain it lies in the Oriskany, according to CampbelP'' and on the Great North Mountain in the Upper Silurian. Considerable oxide of zinc ' Second Penn. Oeol. Survey, M3, p. x. " McCreath, Second Penn. Oeol. Survey, MM, p. 198. » Report MM, 196, M3, p. 33. ■■ C. E. Hesse, ' 'The Paint-Ore Mines at Lehigh Gap, " Trans. Amer Inst. Min. Eng. XIX., 321. " Report MM, p. 193; M3, p. 39. " Report M, p. 66; MM, p. 194; M3, p. 140. ' Report M3, p. 43. » Report MS, p. 1. ° Iron Manufacturers' Guide, p. 650. "J. L. Campbell, The Virginias, July, 1880 " The Virginias, March, 1880, p. 35. '= Ibid.. January, 1880, p. 6. 13 8 00 >• g §^ is rO §< o e THE IRON SERIES {IN PART) 95 collects in the tunnel heads of the furnaces running on Low Moor ores, indicating the presence of this metal in the limonite. ' The Oriskany ores (including those referred by Lyman to the Matcellus) were formerly the chief sources of Virginia iron, and at Longdale and Low Moor afforded very large amounts, but lately the Siluro-Cambrian have taken precedence. The Oriskany ores yield from 40 to 43% Fein the furnace (Pechin), and were non-Bessemer. They have an excellent reputation for foundry and mill work. Another prominent source of brown hematite ores in Virginia has been of recent years the weathered and oxidized upper portions of the great pyrites deposits in Floyd, Grayson and Carroll counties, in the south- western part of the State. This belt extends over 20 miles, and is known as the "Great Gossan Lead." Although uniformly pyrites or pyrrhotite below the water line, it is suflSciently oxi- dized above to yield an ore of about 40 to 41% Fe, with the sulphur not much over one per cent. The greatest depth is attained where the belt crossses the hills. The ores supply a useful mixture for the neighboring Siluro-Cambrian brown hematites.'' The iron ores in Kentucky are found in three widely sepa- rated districts, one near Greenup, in the northeastern corner of the State, known as the Hanging Rock region ; the second near the central part along the Red and Kentucky rivers, known as the Kentucky and Red River region; and the third in the southwestern part near Lyon and Trigg Counties, known as the Cumberland River region. Although the first two contain much limonite, it has altered from nodules of carbonate, and the ores are therefore described under Example 5. One locality near Owingsville, in the second region, has limonites altered from the Clinton hematite. (See Example 6.) The Cumberland region affords limonites in the Subcarboniferous. They are in ' B. S. Lyman, "Geology of the Low Moor, Va., Iron Ores," Trans. Amer. Inst. Mm. Eng., XIV., 801. E. C. Means, "Flue Dust at Low Moor, Va.," Trans. Amer. Inst. Min. Eng., XVII.; 129. E. C. Pechin, "Vir- ginia Oriskany Iron Ores," Engineering and Mining Journal, August 13, 1893, p. 150; "Oriskany Iron Ores at Rich Patch Mountain," Idem, February 1, 8, and 15, 1896; "Iron Ores of Virginia," etc.. Trans. Amer. Inst. Min. Eng., XIX., p. 1016,1890. 'E. C. Moxham, "The Great Gossan Lead of Virginia," Trans. Amer. Inst. Min. Eng , XXI., 133, 1892. 96 KEMP'S ORE DEPOSITS rounded masses, either solid or hollow, and are distributed through a red clay along with angular fragments of chert. The limonite pots are themselves filled with clay or, water.' 3.01.13. In Tennessee the limonites of the eastern portion come mostly under Example %a. In the west they are a south- ern extension of the pot-ore deposits of Kentucky, and show the same associated chert and clay, Safford. has called the rocks containing them the Siliceous Group. The west Tennessee dis- trict projects into Alabama to a small extent.^ 2.01.14. The principal limonite deposits of Alabama come under Example 2 a, as do those of western North Carolina and Georgia. Some limonite is produced in Ohio, but it is all Fig. 11. — Geological Section of the Loio Moor, Va., Iron-ore Bed. After B. S. Lyiaan, Trans. Amer. Inst. Min. Eng., XIV., 801. A' — Marcellus Shale; B — Oriskany Sandstone; C — Lower Helderberg Limestone; D — Clinton Shales. weathered carbonate and is mentioned under Example 5. Hydrated ores are abundant in the Lake Superior region, but are mentioned in connection with hematite. (See also 2.01.-23.) Deposits of brown hematite are worked in a small way in the southeastern part of Missouri, where they rest upon Cambrian strata and have a marked stalactitic character.' Limonites referred to the Cretaceous by N. H. Winchell occur in western Minnesota/ 2.01.15. The Annual Report of the Geological Survey of Arkansas, Vol. I., consists of a report by E. A. F. Penrose on the "Iron Deposits of Arkansas." It at once appears that there is little prospect of Arkansas producing any notable ' W. B. Caldwell, "Report on the Limonite Ores of Trigg, Lyon, and Caldwell Counties," Kentucky Geol. Survey, New Series, Vol. V., p. 251. s W. M. Chauvenet, Tenth Census, Vol. XV., p. 357; J. H. Safford, Geol- ogy of Tennessee, p. 350. = P. N. Moore, Oeol. Survey of Missouri, Report for 1874; F. L. Nason, Mo. Geol. Survey, 1892, II., p. 158. * Bull. VI., Minn. Geol. Survey, p. 151. THE IRON SMBIES {IN PART). 97 amounts of iron ore. Such deposits as have been found are practically all limonite (brown hematite) and are generally very low in iron. The ores occur in five districts, viz. : North- eastern Arkansas, northwestern Arkansas, the valley of the Arkansas River, the Ouachita Mountains, and southern Arkan- sas. They are generally associated with sandstones or cherty limestones. The first-named district makes the best showing. In it the ores are in Lower Silurian (Calciferous or lower) sandstones, cherts and limestones. In the second district they are in Lower Silurian cherts, and Lower Carboniferous sand- stones. In the third they occur with Carboniferous and Lower Carboniferous strata, but are also in the form of recent spring deposits. In the Ouachita Mountains they are with Lower Silurian shales and novaculites. In this district the magne- tite or natural lodestone of Magnet Cove occurs, but it is onlj' an interesting mineral, and of no practical importance. The last district has the ores in sands and clay^ of the Eocene. Its continuation in Texas and Louisiana is referred to below. In eastern Texas, along the latitude of the northern boundarj' of Louisiana, extended beds of limonite are found capping the mesas or near their tops, and associated with glauconitic sands • of Tertiary age. They are described by Penrose^ as (1) brown laminated ores, (2) nodular or geode ores, (3) conglom erate ores. The first form extended beds whose firmness has prevented the erosion of the hills, and which are thought to have originated by the weathering of the pyrites in the greensands and from the iron of the glauconite itself. The second group occur just north of the last, and have probablj' resulted from the alteration of clay ironstone nodules {Cf. Example 5), while the third has formed in the streams by the erosion of the first two and from the smaller ore-streaks and segregations. Limonite also occurs in northwestern Louis- iana.^ Lawrence C. Johnson has also written of these ores,' but the most complete account has been given by W. Ken- nedy.* Mr. Kennedy speaks of the available ores as the "Laminated Ores" and the "Nodular Ores," both belong- ' First Ann. Rep. Texas Oeol. Survey, p. 66; also Bull. Geol. Soc. Amer., III., 44. ' Mineral Resources, 1887, p. 51. ' Fiftieth Congress, First Session, Exec. Doc. No. 195. * "Iron Ores of East Texas," Trans. Amer. Inst. Min. Eng., XXIV,, 258, 863. 98 KEMP'S ORE DEPOSITS. ing, in serious amount, to the greensand beds of the uppei Eocene. An abundant series of analyses is given which shows the ores to be in general rather rich for limoh- ites, and not high in sulphur or phosphorus. Accord- ing to the grade of ore now demanded and obtained on Lake Superior, they are seldom Bessemer ores, but ought to yield excellent foundry irons. While the quantity is large, the situation precludes the use of any fuel but charcoal, and the remoteness of markets will mostly restrict the output to the comparatively limited local demand. The ore can be won by shallow stripping or from exposed beds, up to two feet or so in thickness. The geological relations of these ores are inter- esting and important in that they are derived from greensands, which consist so largely of glauconite, the double silicate of iron and potassium, and which are comparatively deep-sea deposits. The formation of glauconite by precipitation from sea- water, and as a filling of the small chambers in minute shells and organisms indicates^ a marine method for the concentration of iron oxide. It is significant that J. E. Spurr has lately advo- cated a similar source for the ores of the Mesabi range, Minn. (See Example 9e.) Limonite is known in a number of locali- ties in Colorado. The chief productive mines lie in Saguache County, near Hot Springs. They furnish a most excellent ore from cavities in limestones, which are generally, but with no great certainty, considered Lower Silurian. R. Chauvenet states that the ores yield about 43%" Pe in the furnace.^ In Allamakee County, in the extreme northeastern corner of Iowa, important deposits of rich limonites have been dis- covered on Iron Hill near the town of Waukon'* and elsewhere, ' On the formation of greensands, see W. B. Clark, Journal of Geology, II. , 161, 1894. " R. Chauvenet, " Preliminary Notes on the Iron Resources of Col- orado," ^»n. Rep. Colo. State School of Mines, 1885, p. 31; " Iron Re- sources of Colorado," Trans. Amer. Inst. Min. Eng., XVIII., 266. F. M. Endlich, Hayden's Reports, 1873, p. 333. B. T. Putnam, Tenth Census, Vol. XV., p. 483. C. M. Rolker, "Notes on Certain Iron Ore Deposits in Colorado," Trans. Amer. Inst. Min. Eng., XIV., 366. Rec. ' E. Orr, "Brown Hematite in Allamakee County, Iowa," Amer. Ge- ologist, I., 139, 1888. W. J. McGee, "The Pleistocene History of Northeast Iowa," Eleventh Ann. Rep. Dir. U. 8. Geol. Survey, 548, 1891. Samuel Calvin, " Geology of Allamakee Co.," Fourth Ann. Rep. Geol. Surv. Iowa, 97, 1894 Rec. THE IRON SERIES {IN PART). 99 The superficial decay of the rocks in this unglaciated region has been extensive and has left a thick mantle of residual mate- rial. Calvin estimates that a total of about 800 feet of Tren- ton and Galena limestones, Maquekota shales and Niagara limestone have disappeared, leaving behind them the usual clays and the iron ore. The latter is in the form of nodules, pipes and pots, and is as much as 30 feet thick. It has less ocher and clay than is usual in residual deposits, and this fact, together with the amount of iron oxide, leads Calvin to infer more of concentration than would result by simple weathering. The known chemical composition of the beds which have dis- appeared indicates that the strata which were formerly over the area of the ore would have furnished but a fraction of it. Fig. 12. — Ideal cross-section of Iron Hill, near Waukon, Allamakee Co., Iowa. For explanation of letters, see text. Fourth Annual Report Iowa Oeol. Survey, p. 101, 1894. Professor Calvin therefore suggests, as shown in the accom- panying figure, that a depression first formed, into which the iron oxide drained from a wide area. Having once been con- centrated, it then settled down and rested like a mantle upon the hilltop, which now stands in relief although it represents the rock formerly under the depression. In the accompanying Fig. 12, A is the St. Peter's sandstone; i?the remaining Tren- ton limestone; the black area, the present ore; CCC the origi- nal geological section ; EE the depressed outline after consid- erable weathering and erosion, with the production of the ore at D. FF is the present outline. Much limonite occurs at Leadville in connection with the lead -silver ores, and is used as a flux by the lead smelters. Some grades low in silver and rich in manganese have even 100 KEMP'S OBE DEPOSITS. been used for spiegel at Pueblo. For the geological relations, see Example 30. 3.01.16. Limonites in supposed Carboniferous limestone occur in the East Tintic mining district in Utah, and seem to be associated with a decomposed eruptive rock, somewhat as at Leadville. The limonite is chiefly used as a flux by lead- silver smelters.' 2.01.17. Example 3a. Siluro- Cambrian Limonites. — Beds of limonite in so-called hydromica (talcose, damourite), slates and schists, often also with limestones of the Cambrian and Lower Silurian systems of the Appalachians. The great extent, the geological relations and the importance of these deposits warrant their being grouped in a su btype by themselves. They extend along the Appalachians from Vermont to Alabama, and are in the "Great Valley," as it was early termed, which Fig. 13. — Geological Section of the Amenia Mine, DntcTiess County, New York, illustrating a Siluro- Camhrian limonite deposit. After B. T. Putnam, Tenth Census, Vol. XV., p. 133. marks the trough between the Aichean on the east and the first corrugations of the Paleozoic j-ocks, often metamorphosed, on the west. The masses of limonite are buried in ochreous clay, and the whole often preserves the general structure of bhe schistose rocks which they have replaced. The original string- ers of quartz remain, following the original folds. Dolomitic limestone often forms one of the walls, and still less often (but especially in New England) masses of siderite are found inclosed. Manganese is at times present, and in Vermont is of some importance of itself. 3.01.18. The deposits begin in Vermont, where in the vicinity of Brandon they have long been ground for paint. A curious pocket of lignite occurs with them, and affords Ter- tiary fossils. This prompted President Edward Hitchcock, about 1850, to refer all the limonites to the Tertiary, making ' B. T. Putnam, Tenth Census, Vol. XV., p. 490. THE IRON SERIES {IN PART). 101 an instructive example of the occasional hasty generalizations of the early days. Lignite has also been found at Mont Alto, Pa. In northwestern Massachusetts, at Eichmond and West Stockbridge; and just across the State line, in Colmnbia and Dutchess counties, New York, and at Salisbury, Conn., the mines are large, and were among the first worked in the United States. The limonito forms geodes, or "pots," pipes, stalactitic masses, cellular aggregates, and smaller lumps from which the barren clays and ochers are removed by washing. The ore is but a fraction of the material mined and occurs in irregular streaks through the clays, etc. It is mostlj' obtained by stripping and open cuts, and only rarely by underground mining, which would present difficulties with such poor ma- terial for walls. ^ A gap occurs in the succession of the deposits across south- ern New York and New Jersej% although a few minor ones are known in the western part of the latter State, in the mag- nesian limestone of the valleys between the hills of gneiss.^ 3.01.19. In Lehigh County and to the southwest through York County, in eastern Pennsylvania, the limonites are again '. J. D. Dana, " Occurrence and Origin of the New York and New Eng- land Limonites," Amer. Jour. Sci., iii., XIV., 133, and XXVIII., 398. Reo. E. Hitchcock, ' ' Description of a Brown Coal Deposit at Brandon, Vt. , with an Attempt to Determine the Geological Age of the Principal Ore Beds of the United States, " Amer. Jour. Set. , ii. , XV. , 95 ; Hist. Geol. Sur- vey of Vermont, I., 233. See also Lesley, below. A. L. Holley, "Notes on the Salisbury (Conn.) Iron Mines and Works." Trans. Amer. Inst. Min. Eng., VI., 220. J. P. Lesley, "Mont Alto (Pa.) Lignites," Proc. Amer. Acad. Sci., 1864, 463-482; Amer. Jour. Sci., ii., XL., 119. L. Lesque- reux, "On the Fossil Fruits Found in Connection with the Lignite at Brandon, Vt.," Amer. Jour. Sci., ii., XXXII., 355. H. Carvill Lewis, "The Iron Ores of the Brandon Period," Proc. Amer. Assoc. Adv. Sci., XXIX., 437, 1880. J. F. Lewis, "The Hematite (Brown) Ore Mines, etc.. East of the Hudson Eiver," Trans. Amer. Inst. Min. Eng., V., 216. J. G. Percival, Rep. on the Geol. of Conn., p. 132; also, Amer. Jour. Sci., ii., II., 368. R. A. F. Penrose, "Report on Manganese Ores," Oeol. Survey Ark., 1890, Vol, I. (Contains many valuable descriptions of Vermont limonites.) B. T. Putnam, Tenth Census, Vol. XV. C. U. Shepherd, "Notice, etc., of the Iron Works of Salisbury, Conn.," Amer. Jour. Sci., i., XIX., 311. J. C. Smock, Bull. VII. New York State Museum, pp. 12, 53. N. H. and H. V. Winchell, "Taconic Ores of Minnesota and Western New England," Amer. Oeol, VI., 363. 1890. " B. T. Putnam, Tenth Census, Vol. XX., p. 176. See also Oeol. Survey New Jersey, 1880. 102 KEMP'S ORE DEPOSITS. developed in great amount, and run southwesterly, with few gaps, to Alabama. It is in this portion that the "Great Val- ley" (called also the Cumberland Valley, or Valley of Vir- ginia) is especially marked. Wherever the great limestone formation. No. II. of Rogers, is developed the ores are found. This corresponds to the Calciferous, Chazy, and Trenton of New York. Limonites also occur still lower in the Cambrian at about the horizon of the Potsdam gandstorie or in the over lying slates. According to McCreath, they are divisible in Pennsylvania into ores at the top, ores in the middle, and ores at the bottom of the great limestone No. II. Those at the top form the belt along the central part of the valley where the Trenton limestone underlies the Utica or Hudson River slates. Those in the middle are connected with various horizons of fer- ruginous limestones in the Chazy and Calciferous. Those at the bottom along the north or west part of the South Mountain- Blue Ridge range are geologically connected with the Potsdam sandstone, or the slates which intervene between it and the base of the Calciferous.^ Cobalt has been detected on those of Chester Ridge by Boye, but it is a rare and unique discovery.^ 2.01.20. The Siluro-Cambrian limonites run across Mary- land in Carroll and Frederick counties, and are mined tt) a small extent.' These limonites are again strongly developed in the Shenan- doah Valley along the western base of the Blue Ridge, and in southwestern Virginia in the Cripple Creek and New River ' Second Penn. Survey, Rep. MM, p. 199. " Dr. Boye, "Oxyd of Cobalt with the Brown Hematite of Chester Eidge, Penn., Amer. Phil. Soc, January, 1846. P. Fraser, Second Oeol. Survey Penn., Eeps. C and CC; " Origin of the Lower Silurian Limonites of York and Adams Counties," Proc. Amer. Phil. Soc, March. 1875. See also, "Remarks on a Paper qf F. Prime," Idem, December 21, 1877, 355. J. W. Harden, "The Brown Hematite Ore Deposits of South Mountain between Carlisle, Waynesborough, and the Southeast Edge of the Cum- berland Valley," Trans. Amer. Inst. Min. Eng., I., 136. J. P. Lesley, Summary, Final Report, Vol. I., 1893, pp. 305, 341. Rec. A. S. McCreath Second Oeol. Survey Penn., Vol. MM, 199. F. Prime, Second Oeol. Survey Penn., Reps. D and DD; "On the Occurrence of the Brown Hematite Deposits of the Great Valley,' Trans. Amer Inst. Mln. Eng., III., 410; Amer. Jour. Sci., ii., IX., 433; also, XI., 63, and XV., 361. Rec. B. T.- Putnam, Tenth Census, Vol. XV., p. 181. » E. R, Benton, Tenth Census, Vol., XV., p. 354. THE IRON SERIES {IN PART). 103 belt. The ores occur in connection with calcareous shales, cal- careous sandstones, and impure limestones, but have not justi- fied the expectations formed of them. The geological relations are similar to those of the zinc ores described under Example 26, and the pictures of the zinc mines will answer for those worked for limonite. In Carroll County, Virginia, the gossan of the great deposit of pyrite is dug for iron ore. The walls, however, are older than the Cambrian.^ 2.01.21. The limonites of eastern Tennessee are the southern prolongation of the area of southwest Virginia. They lie bet wen the Archean of the Unaka range on the east, and the Upper Silurian strata in the foot of the Cumberland tableland on the west. The ores outcrop in the longitudinal valleys or "coves." The bottoms of these valleys, according to Safford (p. 449), are formed by the shales, slates, and magnesian lime- stones of the Knox group, and in the residual clay left by their alteration the ore is found. The gossan of the neighboring veins of copper pyrites, best known at Ducktown (see Example 16), was originally exploited for iron.^ The Tennessee limon- ite extends across northwestern Georgia, and still farther east ' E, E. Benton, Tenth Census, Vol. XV., p. 361. J. L. Campbell, ■ 'Re- port on the Mineral Prospects of the St. Mary Iron Property, " etc. , The Vir- ginias, February, 1883, p. 19. See also The Virginias, January, 1880, p. 4; March, p. 43. F. P. Dewey, "The Rich Hill Iron Ores," Trans. Amer. lust. Mill. Eng., X., 77. W. M. Fontaine, " Notes on the Mineral Deposits of Certain Localities in the Western Part of the Blue Ridge," The Vir- ginias, March, 1883, p. 44; April, p. 55; May, p. 73; June, p. 92. B. S. Lyman, "On the Lower Silurian Brown Hematite Beds of America," Proc. Amer. Assoc. Adv. Sci., XVII,, 114. A. S. McCreath, "The Iron Ores of the Valley of Virginia," Trans. Amer. Inst. Min. Eng., XII., 103; Engineering and Mining Journal, June, 1883, p. 384. E. C. Moxham, "The Great Gossan Lead of Virginia," Trans. Amer. Inst. Min. Eng., XXI., 133. E. C. Pechin, "The Iron Ores at Buena Vista, Rockbridge County, Virginia." Engineering and Mining Journal, Aug. 3, 1889, p. 93; "Mining of Potsdam Brown Ores in Yiy^nia.,' Engineering and Mining Journal, Sept. 19, 1891, p. 337; "Iron Ores of Virginia and their Develop- ments," Trans. Amer. Inst. Min. Eng., XIX., 101; "Ore Supply for Vir- ginia Furnaces," Engineering and Mining Journal, Vol. LI., 1891, pp. 333, 349. Rec. ' J. M. Safiford, Oeol. of Tenn., p. 448, 1869. B. Willis, Tenth Census, Vol. XV., p. 331. The best works of reference are the recent folios of the U. S. Geological Survey, which cover a large part of southeastern Ten- nessee and the neighboring parts of Alabama and Georgia. 104 KEMP'S ORE DEPOSITS. the so-called Huronian limestones of North Carolina also enter the State. But as even these so-called Huronian schists and associated marbles have been considered by F. P. Bradley to be metamorphosed Silurian (Cambrian), the ores may also be- long under Example 2a. The well-determined Siluro-Cambrian rocks form but a narrovp belt of no great importance in North Carolina.^ The limonites are again strongly developed in Alabama and furnish a goodly proportion of the ore used in the State. They form a belt lying east of the Clinton ores (Example 6), later described. As in Tennessee, they are associated with strata of the Knox group. ^ 2.01.23. Origin of the Siluro- Cambrian Limonites. — Dr. Jackson, of the First Pennsylvania Survey, argued in 1839' that they originated in situ; that is, by the alteration of the rocks in and with which they occur. Percival, in his report on the Geology of Connecticut in 1842 (p. 132), attributed them to the alteration of pyrite in the neighboring mica-slate. Prime, in Pennsylvania, in 1875 and 1878 (Reports D and DD), considers that the iron has been obtained by the leaching of the neighboring dolomites and slates, it being in them either as silicate, carbonate or sulphide; that the ore has reached its position associated with the slates, because, being impervious, they retained the ferruginous solutions; and that the potash abundantly present in the slates probably assisted in precipita- ting it.* Frazer, in 1876,^ in studying the beds of York and Adams counties, Pennsylvania, found the hydromica slates filled with the casts of pyrite crystals, and held these to have been the sources of the iron, because they would afford ferrous sul- phate and sulphuric acid. The latter reacted on the alkali of the ' F. P. Bradley, "The Age of the Cherokee County Rocks, North Car- olina," Amer. Jour. Sci., iil, IX., 379, 330; B. Willis, Tenth Cenms, Vol. XV., p. 367. '' W. M. Chauvenet, Tenth Census. Vol. XV., p. 383. H. McCalley, " Li- monites of Alabama Geologically Considered," Engineering and Minitig Journal, Dec. 19, 1896, 583. For other references to Alabama iron ore deposits, see under Example 6. The folios of the U. S. Geological Survey bearing on this region should be consulted. " Ann. Rep. First Pa. Survey, 1839. " Trans. Amer. Inst. Min. Eng., II. 410. ^ Second Pa. Survey, Rep. C, p. 136. t %*'" -mi. •'\ r . rC JSfc.A THE IRON SEBIES {IN PART). 105 slates, producing sodium sulphate. This, meeting calcium car- bonate afforded calciupa sulphate and sodium carbonate, which latter precipitated the iron. Calcium carbonate alone is, how- ever,abundantly able to precipitate iron carbonate and oxide from both ferrous and ferric sulphate solutibns (even when neutral) without the introduction of the alkali, although this might account for the alteration of the slates.^ 3.01.24. J. D. Dana has written at length on the New England and New York deposits, and finds them alwaj's at or near the junction of a stratum of limestone, proved in many- cases to be ferriferous, and sometimes entirely siderite, and one of hydromica slate or mica schist. In several mines bodies of unchanged spathic ore are embedded in the limonite. Hence Professor Dana explains the limonite as derived by the weath- ering of a highly ferruginous limestone, from which the limon- ite has been left behind by the removal of the more soluble elements, so as practically to replace the limestone in connec- tion with other less soluble matter. The limonite has also at times replaced the schists, probably deriving its substance in part from iron-bearing minerals in them, and cha.nging these rocks to the ochers and clays now found with the ores. These views are undoubtedly very near the truth for the region stud- ied, and have been corroborated by observations of the writer. (Cf. also Example 4.) Weathering limestones do furnish residual clay, ocher, etc., as is shown by the deposits of western Kentucky and Tennessee under Example 2. 2.01.25. Another hypothesis early formulated and advo- cated by many is that the limonites have been derived from the surface drainage of the old Appalachian highlands, then have been precipitated in still water and have been buried up where they are now found. A precipitation around the shores of a ferruginous sea has also been urged on the analogy of certain explanations of the Clinton ore. (Example 6.) Their supposed Tertiary age has. already been remarked. All these views are essentially hypothetical and have no good foundation.^ ' See F. P. Dunnington, "On the Formation of Deposits of Manganese," Amer. Jour. Soi., ili., XXXVI., p. 175. (Experiments 10 and 11.) 'See H. D. Rogers, Trans. Asso. Amer. Oeol. and Nat., 1843, p. 345; E. Hitchcock, Geol. Vt, Vol. I., p. 233; J. P. Lesley, Iron Manufacturers' Guide, p. 501; Rep. A, Second Pa. Survey, p. 83; J. S. Newberry, International Review, November and December, 1874. 106 KEMP'S ORE DEPOSITS. ANALYSES OF LIMONITES. 2.01.26. All published analyses, except when forming a sufBciently large and continuous series from the output of any one mine, are to be taken with caution. Ores necessarily vary much, and a single analysis or a selected set may give a very wrong impression. The percentage in iron is different for dif- ferent parts of the same ore body. The few that follow have been selected to show the range and the average. The highest are exceptionally good, the lowest less than the average, and the medium values indicate approximately the general run. Limonites afford from 40 to 50%' Fe as actually exploited, but it is not difficult to find individual analyses that run higher. They are not, generally speaking, Bessemer ores. ANALYSES OF LIMONITES. Fe. P. S. SiO, AlaO, H,0. Berkshire County, Mass 47.53 50.48 46.45 39.73 56.30 43.34 50.91 50,89 53.37 43.00 44.71 59.93 0.187 0.353 0.370 0.059 0.135 0.636 0.337 0.325 0.034 0.030 0.666 Connecticut Dutchess County, New York Staten Island 0.391' 0.030 iiiod 14.190 5.165 3.056 3.590 12 41 Pennsylvania Virginia (Low Moor) Tennes.see (Lag;range Furnace) . . Alabama Colorado 0.300 7.900 30.000 0.700 Colorado, average 13 00 Prosser mine, Oregon. 14 40 SIDERITE OR SPATHIC ORE. 2.01 27. Siderite is the protocarbonate of iron. As a min- eral it often contains more or less calcium, magnesium, and manganese. When of concretionary structure, embedded in shales and containing much clay, the ore is called clay iron- stone. When the concretions enlarge and coalesce, so as to form beds of limited extent, generally containing much bitumi- nous matter, they are called black-band, and are chiefly devel- oped in connection with coal seams. 2.01.28. Examples. Clay Ironstone. — The name is applied to isolated masses of concretionary origin (kidneys, balls, etc.) THE IRON SERIES {IN PART). 107 which may at times coalesce to form beds of considerable extent. They are usually distributed through shales, and on the weathering of the matrix are exposed and concentrated. They are especially characteristic of Carboniferous strata and differ from black-band only in the absence of bituminous mat- ter and in the consequent drab color. They weather to limon- ite, generally in concentric shells with a core of unchanged carbonate within. Fossil leaves or shells often furnish the nucleus for the original concretion, and are thus, as at Mazon Creek, 111., beautifully preserved. When in beds the ore is sometimes called flagstone ore; when broken into rectangular masses by joints, it is called block ore. 2.01.29. Example 3a. Black-hand. — The name is applied to beds consisting chiefly of carbonate of iron with more or less earthy and bituminous matter. They are of varying thickness, though rarely more than six feet, and are almost invariably associated with coal seams. They are thus especially found in the Carboniferous system, and to a far less degree in the east- ern Jura-Trias. They are also recorded with the Cretaceous coals of the West. It is not possible to separate the two varie- ties in discussing their distribution. The various productive areas are taken up geographically, beginning with the Appa- lachian region. 2.01.30. The carbonate ores are of great importance in the Carboniferous of western Pennsylvania and in the adjacent parts of Ohio, West Virginia and Kentucky. In these States the system is subdivided in connection with the coal, from above downward, as follows : I. The Upper Barren Measures, Permo-Carboniferous, or Dunkard's Creek Series; II. The Upper Productive Coal Measures, or Monongahela Eiver Series; III. The Lower Barren Measures, or Elk Eiver Series; IV. The Lower Productive Coal Measures, or Allegheny River Series; V. The Great or Pottsville Conglomerate. In the Upper Barren .Measures of Pennsylvania, according to McCreath, there is hardly a stratum of shale or sandstone without clay ironstone nodules, but no continuous beds are known.' The deposits are not of great actual importance, and are worthy of only passing mention. In the Upper Productive Coal Measures some ore occurs associated with the Waynes- ^ Second Pa. Survey, Rep. K, p. 386; MM, p. 159. 108 KEMP'S ORE DEPOSITS. burg coal seam, and again, just under the Pittsburg seam, there is considerable known as the Pittsburg Iron Ore Group. This latter ore becomes of great importance in Fayette County, and extends through several beds.^ The Lower Barren Meas ures in Pennsylvania also contain carbonate ore in a number of localities. The most persistent is the Johnstown ore bed, near the base of the series. There are two additional beds just over the Mahoning sandstone. The Lower Coal Measures are the chief ore producers in all the States. They furnish balls of clay ironstone in very many localities in western Pennsylvania, which will be found recorded with many additional references in Eeport MM, p. 174, Pa. Qeol. Survey. The nodules are scattered through clay and shales. The so-called Ferriferous limestone, which lies a few feet below the Lower Kittanning coal seam, affords in its upper portion varying thicknesses of carbonate ore, known as "buhrstone ore," which is altered in large part to limonite. Some little carbonate ore was found in the early days in the anthracite measures of eastern Pennsylvania. Several beds of the same occur in the Great Conglomerate and its underlying (Mauch Chunk) shales. They are chiefly developed in south- western Pennsylvania (Report KK), and may form either entire beds or disseminated nodules. The limonites of the Marcellus stage that pass into carbonates in depth in Perry and the neighboring counties have already been mentioned under Example 2. In West Virginia both Upper and Lower Meas- ures afford the ore. . From the latter black-band is extensively mined on Davis Creek, near Charleston.'' 2.01.31. In Ohio a number of nodular deposits are known, but practically no ore is produced above the Mahoning sand- stone of the Lower Coal Measures. Below this sandstone the ores are extensively developed. They extend up and down the eastern part of the State, and are both black- band and clay ironstone. Orton identifies twelve different and well-marked horizons distributed through the Lower Measures. He distin- guishes the stratified ores, mostl}' black-band, and the concre- ' Rep. MM, p. 162; KK, p. Ill; L, p. 98. ' M. F. Maury and W. M. Fontaine, Resources of West Virginia, 1876, p. 247. THE IRON SERIES {IN PART). 109 tionary ores, including kidney ores, block ores, and- limestone ores/ 2.01.32. The general distribution of the iron ores of Ken- tucky has already been outlined under Example 2. The Hang- ing Rock rfegion is a southern prolongation of the Ohio district of the same geological horizon. P. N. Moore has classified the local ores as limestone ores, which are associated with lime- stone, block ores, and kidney ores. The last two names refer to the fracture or shape of the masses. They occur associated with the usual clay and shale. Farther west, between the Ken- tucky and Red rivers, are the other deposits, the principal one of which comes low in the series, just over the Subcarbonifer- ous limestone.' 2.01.33. Small quantities of black-band have been found in the Deep River coal beds, in North Carolina, associated with the Triassic coals.' A large bed, or series of beds, has recently been reported from Enterprise, Miss., in strata of the Claiborne stage. They run from ten to eighteen feet in thickness, and extend for miles.* Scattered nodules have been noted at Gay Head, Martha's Vine- yard. ° Carbonate ores are as yet of no importance in the coal measures of the Mississippi Valley. They have been found associated with the Cretaceous coals of Wyoming and Colo- rado — and indeed the first pig iron of the latter State was made from them in Boulder County — but they are not an important .source of ore.° An extended bed of very excellent carbonate has recently been discovered with coal near Great Falls, in the Sand Coulee region of Montana. Being near coal, limestone, ' Geol. of Ohio, V., p. 378, and supplemental report on the Hanging Rook region in Vol. III. ' P. N. Moore, " On the Hanging Rock District in Kentucky," Kentucky Geol. Survey, Vol. I., Part 3. s B. Willis, Tenth Census, Vol. XV., p. 306; W. C. Kerr, Oeology of North Carolina, 187.5, p. 225. ■■ A. F. Brainard, "Spathic Ore at Enterprise, Miss.," Trans. Amer. Inst. Min. Eng., XIV., 146. ' W. P. Blake, "Notes on the Occurrence of Siderite at Gay Head, Mass.," Trans. Amer. Inst. Min. Eng., IV., 113. " R. Chauvenet, "Notes on the Iron Resources of Colorado," Ann. Rep. Colo. School of Mines, 1885, 1886; Trans. Amer. Inst. Min. Eng., XVIII., 266. 110 KEMP'S ORE DEPOSITS. and other iron ores, it promised to be of considerable impor- tance/ 2.01.34. Example 4. Burden Mines, near Hudson, N. Y. Elongated lenticular beds of clay ironstone, passing into sub- crystalline siderite, enclosed conformably between underlying slates, and overlying calcareous sandstone, of the Hudson Kiver stage. The ore occurs in four "basins," which outcrop ' O. C. Mortson, Mineral Resources U. S., 1888, p. 34. THE IRON SERIES {IN PART). HI along the western slope of a series of moderate hills, just ea£t of the Hudson River. The hills have been shown by Kimball to be the eastern halves of anticlinal folds now reduced by ero- sion to easterly dipping monoclines. The western half of the ore bodies has been eroded away, leaving an outcrop 44 feet thick as a maximum, which pinches out along the strike and dip. The basins extend from southwest to northeast, parallel to the trend of the hills. The beds are more or less faulted. The southern part of the second basin affords Bessemer ores, but the others are too high in phosphorus. At this point the principal mining has been done. According to Olmstead, some varieties are richer in phosphorus than others, but they are so intimately mixed as not to be practicably separated. Up to 1889 the mines had produced 450,000 tons of roasted Bessemer ores. 2.01.36. In their geological relations the ores are of the greatest interest, as they occur in the western limit of the metamorphic belt, which forms the basis of the Taconic con ■ troversj', yet in strata which have been identified bj' fossils. Beds of limonite hitherto regarded as Siluro Cambrian occur to the east; and should further study, on the lines developed chiefly by J. D. Dana, W. B. Dwight, and C. D. Walcott, clear up their stratigraphical relations, the work done in devel- oping the structure of the siderite basins, as pointed out by Kimball, may be of great aid in explaining them. Very similar bodies of siderite occur with these limonites. (Exam- ple 2a.) The Burden ores are relatively high in magnesia, and this leads Kimball to suggest' their original deposition from the off-shore drainage of the basic rocks of the Archean highlands. Further, it may be added that the ores in their lenticular shape are highly suggestive of a possible origin for magnetite deposits, and they are again referred to under ' ' Mag- netite." Other deposits of siderite in the shales of the Marcel- lus stage are known and were formerly worked at Wawar- sing, Ulster County, across the Hudson River.' ' J. P. Kimball, "Siderite Basins of the Hudson River Epoch," Amer. Jour. Sd., III., xl 155. I. Olmstead, "Distribution of Phosphorus in the Hndson River Carbonate," Trans. Amer. Inst. Min. Eng., XVIII., 253. R. W. Raymond, ' 'The Spathic Ores of the Hudson River," Trans. Amer. Inst. Min. Eng., IV., 309. J. 0. Smock, Bulletin VII. of New York State Mus eum on Iron Ores, p. 62. 112 KEMP'S ORE DEPOSITS. 2.01.36. Example 5. Eoxbury, Conn. A fissure vein in gneiss, six to eight feet wide, of crystalline siderite.with which are asociated quartz and a variety of metallic sulphides, galena, fchalcopyrite, zinc blende, etc. Although productive in former years, it is no longer worked, and is of scientific more than economic interest, being a unique deposit. It has fur- nished many fine cabinet specimens.^ 2.01.37o The spathic ores are the lowest in iron of all, and in the raw state are often, if not always, far below the limit of profitable treatment. Calcination, however, drives off the carbonic acid and moisture and brings the percentage of iron up to a merchantable grade. The later development of the iron industry in this country has been unfavorable to spathic ores, and year by year their amount has decreased until now it is nearly obliterated, being only about one per cent, of the total. 2.01.38. The subjects of limonite and siderite cannot well be passed without further reference to their genetic relations as connected with limestone. The processes involved concern not alone these ores, but also the more metamorphic forms — ^hema- tite and magnetite — into which they may pass by reason of subsequent changes. It was stated earlier (2.01.05) that cal- cium carbonate precipitated from ferric salts, ferric hydrate, and from ferrous salts, ferrous carbonate, which in the presence of oxygen quickly changed to ferric hydrate. J. P. KimbalP has recently added a note on the chemistry of the process which modifies it somewhat. He brings out the fact that it is the hydrous carbonate of iron' which is precipitated from ferrugi- noiis salts by the various alkaline carbonates, and that, being an unstable salt, it quickly oxidizes to a hydrous oxide. From this the argument is made that bodies of siderite, or anhydrous ferrous carbonate, could not have originated by direct precipi- tation, but must have done so by pseudomorphous replacement of limestone. Dr. Kimball then follows out the possible meta- morphism or changes of these bodies to other forms of iron ore, ' J. P. Lesley, Iron Manufacturers' Guide, p. 649. C. U. Shepherd, "Report on the Geology of Connecticut," 1837, p. 30, Amer. Jour. Sci., I., xix. 311. ' J. P. Kimball, "Genesis of Iron ores by Isomorphous and Pseudomor phous Replacement of Limestone,' Atner. Jour. Sci., September, 1891, p 231, and conclusion in the Amer. Geol., December, 1891. THE inON SERIES {IN PART). 113 citing, however, among many that are unexceptionable, some instances as possible examples for which the field relations give but slight justification. The specular ores with the porphyries of Missouri are of this latter character, and the work of C. H. Smyth, Jr., later cited, on the oolitic Clinton hematites gives strong ground for thinking them accumulations in shallow waters as concentric layers upon original nuclei of quartz. 2.01.39. While the importance of limestone as a cause of the formation of bodies of iron ore cannot he too highly empha- sized, and it is quite possible that some puzzling ones, such as many magnetite beds, have originated in this way, and that the limestone has so entirely disappeared as to give slight clue to its original presence: yet it must not be overlooked that siderite often does form in nature quite independently of cal- cite, and that conditions must be often such as to make this possible. If vuggs with free crystals, or if cleavage masses with the proper angle occur in a deposit, we must admit that the siderite is produced under circumstances not different from those which prevailed during the formation of the walls or of the massive mineral. Repeated experience indicates that these are not extraordinary. CHAPTER 11. THE IRON SERIES CONTINUED — HEMATITE, RED AND SPECULAR. 2.03.01. The sesquioxide of iron, FaOs, is always of a red color when in powder. If it is of earthy texture, this color shows in the mass, and the ore is called red hematite ; if the ore is crystallized, the red color is not apparent, and the bril- liant luster of the mineral gives it the name specular hematite. The red hematites are first treated. 3.02.02. Example 6. Clinton Ore. — Wherever the Clinton stage of the Upper Silurian outcrops, it almost invariably con- tains one or more beds of red hematite, interstratified with the shales and limestones. These ores are of extraordinary persist- ence, as they outcrop in Wisconsin, Ohio and Kentucky in the interior, and then beginning in New York, south of Lake Ontario, they run easterly across the State. Again in Penn- sylvania they follow the waves of the Appalachian folds and extend south into West Virginia and Virginia in great strength. They are found in eastern Tennessee and northwest- ern Georgia, and finally in Alabama are of exceptional size and importance. The structure of the ore varies somewhat. At times it is a replacement of fossils, such as crinoid stems, molluscan remains, etc. (fossil ore) ; again as small oolitic con- cretions, like flaxseed (flaxseed ore, oolitic ore, lenticular ore) ; while elsewhere it is known as dyestohe ore. The ore in many places is really a highly ferruginous limestone, and below the water level in the unaltered portion it often passes into lime- stone, while along the outcrop it is quite rich. 2.02.03. In Dodge County, southeastern Wisconsin, the ore in 14 to 26 feet thick, and consists of an aggregate of small lenticular grains.^ In Ohio it outcrops in Clinton, Highland > T. C. Chamberlin, Geol. Survey Wis., Vol. I., p. 179. R. D. Irving, "Mineral Besouroes of Wisconsin," Trans. Amer. Inst. Min. Eng., VIII., 478; Geol. Survey Wis., Vol. I., p. 625. THE IRON SERIES aONTINUED. 115 and Adams counties, in the southwestern portion of the State along the flanks of the Cincinnati Arch, but it is thin and poor in iron, although rich in fossils.^ A small area of the Clinton has furnished considerable ore in Bath County, Kentucky, where it is altered to limonite.^ 2.02.04. Coming eastward, the limestones and the shales of the Clinton outcrop in the Niagara River gorge in New York, but show no ore. This appears first in quantity in Wayne County, a hundred miles east and just south of Lake Ontario. One bed reaches 20 to 22 inches. Farther east are the Sterling Till \o'±. J , l_! Limestone 0-6 ^^Sr^-^^^j:f^£^^^7 Ore 2' Fig. 16. — Clinton Ore, Ontario. Wayne County, New York. After C. H. Smyth, Jr. mines, in Cayuga County ; and again near Utica, in the town of Clinton, which first gave the ore its name, it is of great eco- nomic importance. There are two workable beds, the upper of which, with a thickness of about two feet, is the only one now exploited. Beneath this are 12 or 15 inches of shale, and then the second bed of 8 inches of ore.' Some 26 feet over the upper bed is still a third, which is too low grade for mining. It is four to six feet thick, and is locally called red flux. It consists of pebbles and irregular fragments of fossils, which are coated with hematite and cemented with calcite. ■ J. S. Newberry, Oeol. of Ohio, Vol. III., p. 7. E. Orton, Geol. of Ohio, Vol v., p. 371. » N. S. Shaler, Geol. of Ky., Vol. III., 163. ' A. H. Chester, "The Iron Region of Central New York,'' address be- fore the Utica Merchants and Manufacturers' Association, Utica, 1881. J. C. Smock, Bull. VII. of N. Y. State Museum, June 1889. C. H, Smyth, Jr., "On the Clinton Iron Ore," Amer. Jour. Sci., June, 1893, p 487. Zeitfichr. fUrprakt. Geologie, 1894, 804. 116 KEMP'S ORE DEPOSITS. 2.03.05. The rocks of the Clinton thicken greatly in Penn- sylvania and run south westward through the central part of the State. Six different ore beds have been recognized, of which the lower are probably equivalent to the southern dyestone ores. iSii . 1 -x. "ffls Calcareous Sandstorva and f thin Shale layers 5'0 + Non-Oolitio Ore I (Red FIuk) 6 Calcareous f Sandstone 6 Blue Shale and thin f Sandstone layers 15' Oolitic Ore 2 Shale 2' , Oolitic Ore 1 Blue Shale and thin i ^ Sandstone layers 1003 Fig. n.— Clinton Ore, Oiinton, New York. After 0. H. Smyth, Jr. The ores are of chief importance in the Juniata district. The belt extends southwestward across Maryland and eastern West Virginia, where the beds are quite thick, although as yet not much developed, and appears in the extreme southwest corner of Virginia. Thence it runs across eastern Tennessee, and is of very great importance. The lines of outcrop aj'e ' J. H. Dewees, " Fossil Ores of the Juniata Valley," Penn. Oeol. Sur- vey, Rep. F. E. d'Invilliers, Ibid., Rep. F3 (Union, Snyder, Mifflin, and Juniata counties). A. S. McCreath, Ibid., Rep. MM, p. 231. J. J. Stevenson, Ibid., Reps. MM and T3 (Bedford and Fulton counties). I. C. White, Ibid., Reps. MM and T3 (Huntingdon County) . H. H. Stoek, " Ores at Danville, Montour County," Trans. Amer. Inst. Min. Eng.,XX., 369. THE IRON SERIES CONTINUED, 117 known as "dyestone ranges." They lie west of the Siluro-Cam- brian limestones (Example 2o) and in the edges of the Cum- berland tableland. Four or five are known, of which the largest extends across the State. This ore is more fossiliferous Fig. 18. — Clinton Ore, Eureka Mine, Oxmoor, Ala. After C. H. Smyth, Jr. toward the south and more oolitic toward the north. It is very productive in the Chattanooga region.' 2.03.06. The Clinton just appears in northwestern Georgia, and continues thence into Alabama, where it is again of great "''So 'Su /■y^ Diagram No.l LJ 1 ""^^^^^^^^----^ z-<-^sb^ -CO '^r^S _ J"^""""^---- ir-T- ^S '>^ Fig. 19. — Cross-section of the Sloss Mine, Red Mountain, Ala. importance, and, with the less productive Siluro-Cambrian limonites, furnishes practically all the ore of the State. The outcrop can be traced almost continuously for 130 miles. The ore is rich in fossils and occurs in several beds, which, although averaging much less, may aggregate, as at the Eureka furnace, as much as 34 to 37 feet. The chief mines are in Red Mountain, ' Killebrew and SafEord, Resources of Tennessee. E. C. Pechin, "The Iron Ores of Virginia," etc., Trans. Aiiiet: Inst. Min. Eng., XIX., 1016. J. B. Porter, "Iron Ores, Coal, etc., in Alabama, Georgia, and Tennessee," Trans. Anier. Inst. Min. Eng., XV., 170. J. M. Saflford, Oeol. of Tenn. P. N. Moore, Virginias, May, 1880, p. 78. 118 KEMP'S ORE DEPOSITS. a local name for the northeast and southwest ridges, in which the ore outcrops, east and south of Birmingham. Folds and faults have brought the beds into close proximity with the coal and limestone of the region, and thus into a position very favorable for economic working.' The accompanying map. Fig. 20, illustrates the geography and economic geology of the Birmingham district. In expla- nation it may be said that the three coal fields, the Warrior, the Cahaba, and the Coosa, make three elevated basins, formed in part by synclinal foldings and in part by faulting. The intervening strips are relatively depressed and constitute the so-called valleys, each of which has its own name. Thus there is a long valley in which Birmingham is situated and which forks at the northeast corner of the map. The central portion of it consists of Cambrian and Lower Silurian rocks, which yield brown hematite ores, as indicated on the map. They, however, are a minor feature and do not form over 10% of the total furnace supply. On each side of the valley there is a ridge called Red Mountain, mostly formed by Clinton strata, with Trenton limestone beneath and black Devonian shale above. The Clinton reaches a thickness of 150 feet, but is quite variable in character. It may contain as many as five or more beds of ore of differing thicknesses and somewhat con- trasted composition and structure. The best of these are worked. The Clinton beds in Red Mountain dip on each side away from the center of the valley, and really are the remains of an anticline eroded at its crest. The anticline is of the usual Appalachian type with steeper dips on one flank, in this case the northwestern, than on the other, and the crest is nearer the northwest side than the northeast. The dip at one important mine is shown in Fig. 18. The most productive points are east and south of Birmingham, and along this line the largest mines are situated. The ore is chiefly won bj^ open cuts, and is laid bare by stripping off the hanging. Curiously enough, ' A. F. Brainerd, "On the Iron Ores, Fuels, etc., of Birmingham, Ala.," Trans. Amer. Inst. Min. Eng., XVII., 151. "TheSloss Iron Ore Mines," Engineering and Mining Journal, Oct. 1, 1892, p. 318. T. S. Hunt, "Coal and Iron in Alabama," Trans. Amer. Inst. Min. Eng., XI., 236. J. B. Porter, "Iron Ores, Coal, etc., in Alabama, Georgia, and Tennessee," Trans. Amer. Inst. Min. Eng., XV., 170. E. A. Smith, Alabama Oeol. Survey, 1876; also Proc. Amer. Assoc. Adv. Sol, XXVII., 346. THE IRON SERIES CONTINUED. 119 Fig. 30.— Voj; af the Vicinity of Birminyham, Ala. From the Transaciiona of the American Iiutitute if Miidnr/ Engineers, Vol. XIX., Plate IV. 120 KEMP'S ORE DEPOSITS. for an ore in the midst of limestone and limey shales, it is pre- vailingly siliceous, so that non-siliceous or calcareous varieties are much-sought-for mixtures. The red hematites are also exposed in Murphrees Valley and are developed in some large and productive openings. While on the west this valley has the normal and anticlinal flank, it is faulted along the east so that the Clinton measures lie against the Cambrian shales and are overthrown to a steep northwesterly dip. 3.02.07. Red hematite, supposed to bo of the Clinton stage, occurs in Nova Scotia in very considerable amount, in Pictou and Antigonish counties.' 2.02.08. In general the Clinton ore is characterized by a high percentage of phosphorus, and is seldom, if ever, available for Bessemer pig. It is chiefly employed for ordinary foundry irons. The percentage in iron varies much. Experience at Clinton, N. Y. , shows that it averages about 44%' Fe in the fur- nace. These hematites have undoubtedly originated in some cases by the weathering of ferruginous limestones above the water level. I. C. Russell has shown that the unaltered lime- stones at the bottom of a mine in Atalla, Ala., 250 feet from the surface, contained but 7.75%" Fe, while the outcrop afforded 57.52%". J. B. Porter has recorded the gradual increase of lime also in another Alabama mine from a trace at the outcrop to 30.55% at 135 feet. Other writers have explained these beds as due to the bringing of iron in solution into the sea of the Clinton age and to its deposition as small nodules, etc., or as ferruginous mud (Roger, Lesley, Newberry). In this way an oolitic mass has originated, as in the modern Swedish lakes (Newberry). (See Example 1.) N. S. Shaler has argued, on the basis of the Kentucky beds, that the iron has been derived from the overlying shales, and descending in solution has been precipitated by the lower-lying limestones. ' As the shales are themselves calcareous, this seems improbable. A. F. Foerste has shown that the ore is very often deposited either in the interstices of fragments of bryozoans or as replacing their sub- stance. The rounded, water-worn character of the original fragments is regarded as occasioning the apparent concretion- ary character. Admirable work upon the origin of the ore has - Sir J. W, Dawson, Acadian Oeology, p. 591. Fletcher, Can. Geol Survey, 1886. THE IRON SERIh'S CONTINUED. 1^1 also been done by C. H. Smyth, Jr. He finds that the small oolites, or concretions, as they occur at Clinton, N. Y., and many other localities, have a water-worn grain of qnartz as a nucleus. The character of the grain is such that it has evi- dently been derived from granitoid or schistose rocks. The hematite comes off at times in concentric layers, when tapped gently. It may also be dissolved away so as to leave a sili- ceous cast or skeleton of the spherule. Dr. Smyth thus makes a strong argument that the ores in such cases are concretion- ary, and that they were formed in shallow waters around the nuclei of sand. But he also admits, as others quoted above have indicated, that the replacement of bryozoa and the weath- ering of ferruginous limestone have in many localities played their part. The iron ore is in the latter case a residual prod- uct, but now the mine waters are depositing calcium carbonate rather than removing it.' 2.03.09. Glenmore Estate, Greenbrier County, West Vir- ginia. A bed of red hematite in Oriskany sandstones. Limon- ites are abundant in the Oriskany of Virginia, and the hema- tite may have been derived from some such original.^ 2.03.10. Mansfield Ores, Tioga County, Pennsylvania. Three beds of ore are found in the strata of the Chemung stage of Tioga County, Pennsylvania. They are known as (1) the Upper or Spirifer Bed, (3) the Middle or Fish Bed, and (3) the Lower Ore Bed. No. 1 is full of shells and is about 300 feet below the Catskill red sandstones, and at Mansfield is two to three feet thick. No. 3 is oolitic, resembles the Clinton ore, and affords fish remains. It lies about 300 feet below No. 1 ' A. F. Foerste, " Clinton Group Fossils, with Special Reference to Col- lections from Indiana, Tennessee, and Georgia," Avier. Jour. 8ci., iii., XL., 253. (Abstract; original not cited) "Clinton Oolitic Iron Ores," Amer. Jour. Sci., iii., XLI., 28. Eec. "Notes on Clinton Group Fossils, with Special Reference to Collections from Maryland, Tennessee, and Georgia, " Proc. Bost. Soc. Nat. Hist. , XXIV. , 263. J. P. Lesley, Iron Man- ufacturers' Guide, p. 611. J. S. Newberry, "Genesis of the Ores of Iron," School of Mines Quarterly, November, 1880, p. 13. Rec. H. D. Rogers, Geol. of Penn., Vol. IL, p. 127. N. S. Shaler, Oeol. of Ky., Vol. III., p. 103. C. H. Smyth, Jr., "On the Clinton Iron Ore," ^raer. Jour. Sci., June, 1892, p. 487. Rec. " Die Haematite von Clinton in den oestlichen Vereinigten Sta ahia i" Zeitscher. fUr prakt. Oeologie, 1894, 304. ' W. N, Page, "The Glenmore Iron Estate, Greenbrier County, West Virginia," Trans. Amer. Inst. Min. Eng., XVII., 115. 3 23 KEMP'S ORE DEPOSITS. and varies up to six or seven feet thick. No. 3 is 100 to 200 feet lower, and contains small quartz pebbles,^ The ore is not rich, and but little has been mined. It is a brownish red hema- tite.' 2.02.11. Beds of red hematite are reported by Schmidt in the Lower Carboniferous of western central Missouri." 2.02.12. Example 7. Crawford County, Missouri. Bodies of finely crystalline specular hematite, associated with chert, sandstone fragments, residual clays and some pyrite in conical or rudely cylindrical depressions in the Cambrian (Ozark) Series. A broad area of upheaval runs across central Missouri from the east, near St. Louis, to the south- western part of the State. In the eastern and central portions it is chiefly composed of Cambrian and Silurian strata, but to the southwest Lower Carboniferous come in (see 2.06.06). The hematites here considered belong in the Cambrian. In the region of the mines there is a heavy sandstone stratum, earlier called the "Second Sandstone, " but in the later reports described as the Roubidoux. It is underlain by a heavy limestone stra- tum locally called the Gasconade. The Ozark uplift was formed at the close of the Lower Carboniferous and has remained exposed to atmospheric agencies ever since. Their effects are shown in the great mantles of residual clay, which are widely distributed, and in the phenomena of the hematite deposits. Dr. A. Schmidt, of the Missouri Survey of 1872 (Report on Iron Ores, p. 66), wrote that these had replaced the pre-existing rock, or had been deposited in hollows in the then existing sur- face. Pumpelly, however, in 1885,* advanced a more probable hypothesis, which is strongly supported by F. L. Nason. The region is and has long been one of sink-holes caused by sub- terranean drainage through the Gasconade limestone and the caving in, at times, of the overlying sandstone. Cavities were thus afforded in which ferruginous waters might stand and precipitate their dissolved burden of ore. Nason shows that ' A. S. McCreath, Rep. MM, Second Penn. Survey, p. 331. ■^ J. P. Lesley, Oeol. of Penn., 1888, Vol. I., p. 311. A, Sherwood, Rep. G, Seoond Penn. Survey, pp. 33, 37, 41, 42, 67. A. S. McCreath, Rep. MM, Second Penn. Survey, p. 351. " A. Schmidt, "Iron Ores and Coal Fields," Missouri Oeol. Survey, 1872, p. 169. , * Tenth Census, Vol. XV., p. 13. Fig. 21. — View in Cherry Valley Mine, showing sandstone ivith under- lying cherty clay. The sandstone dips southeast inward toward the ores. After F. L. Nason, Report on Iron Ores of Missouri, p. 125. Plate VI. i^Ai^ '- ^ Fig. 32. — Section of the northern end of the Cherry Valley Mine. 1, Clay detritus; 2, Sandstone; 3, Cherty and. slaty clay; 4, Ores; 5, Blocks of sandstone. After F. L. Nason, Re- port on Iron Ores of Missouri, p. 131. J L Fig. 23. — Cross section of the Cherry Valley Mine. 1. Sandstone; 3, Clay and chert; 3, Sandstone dipping inward; 4, Magnesian limestone. After F. L. Nason, Report on the Iron Ores of Missouri, p. 134. THE IRON 8EBIE8 CONTINUED. 123 several of the largest mines are along lines of old drainage vallej's. The edges or walls of the pits are formed by the sandstone which dips inward, as shown in the accompanying figures. Just how much overlying rock has washed away does not appear with all desirable certainty, but the presence of large amounts of chert mixed with the ore indicates that the cap must have been to a great extent limestone with interbedded layers of this rock. As Nason states' the limestone that fell into the cavities has been replaced with ore. It is very proba- ble that the former was an important precipitating agent to the latter. A fossil crinoid was found at Cherry Valley, replaced by hematite, giving evidence that even Lower Carboniferous strata had been present. The leaching of these old, overlying beds and the superficial drainage seem to indicate the method of derivation of the ore. The most productive counties are Crawford, Phelps and Dent, but smaller deposits occur in several others. The largest mines are the Cherry Valley, with a total product of over half a million tons, the Simmons Mountain, which has yielded about half as much, and the Meramec with 375,000. The total product of all the mines is computed by Nason at about two and one-quarter millions of tons. A sample from a stockpile made up at St. Louis furnaces from several mines, yielded Fe 56.43, P 0.065 (Nason, I. c. p. 157), but many are much lower in iron. In former years 100,000 to 200,000 tons were annually produced ; recently, however, much Jess. Some anomalous features are presented by these ores in that they are specular hematite in a practically unmetamorphosed sandstone, whereas some less crystalline form would naturally be expected. Nason believes that they were originally sulphides, and that the heat generated by the decomposition of this mineral has effected the change to specular.^ 3.02.13. Examples. Jefferson County, New York. Large bu< irregular bodies of red hematite associated with crystalline ' "Iron Ores of Missouri," p. 138, Mo. Geol. Snr., 1892. ' W. M. Chauvenet, Tenth Census, Vol. XV., 1885, p. 403. F. L. Nason, '■ Report on Iron Ores," pp. 119-1.56, 218-231. Missouri Geol. Survey, 1892. Eec. R. Pumpelly "On the Origin of the Ore," Tenth Census, Vol. XVI. , p. 12. Rec. A. Schmidt, "Iron Ores and Coal Fields," J/wsoMn Oeol Survey, 1873, p. 124. 124 KEMP'S ORE DEPOSITS. limestone, serpentine, and pyritous gneiss and overlain by Pots- dam sandstone. The crystalline limestone is certainly pre- Cambrian, and would be called Algonkian in the later use of this term, and later Laurentian in the earlier nomenclature.' In a recently issued report to James Hall, State Geologist, C. H. Smyth, Jr., has named the limestone series the Oswe- gatchie. The ore bodies occur along a northeast belt, from Philadelphia, Jefferson .County, to Gouverneur, St. Lawrence County. They range up to 30 or 40 feet in thickness and con- sist of red, earthy hematite in porous or cellular masses, with some specular. Many interesting minerals, including siderite, millerite, chalcodite, quartz, etc., are found in cavities. The alignment of the mines along a marked belt has given some ground for thinking them interbedded deposits, and their asso- ciation with Potsdam sandstone has created the impression that they are of Cambrian (or. as it was then called. Lower Silu- rian) age.^ J, P. Kimball has stated that they are replace- ments of Calciferous limestone. ' E. Emmons in the ' ' Report on the Second District" of the early New York Survey, regarded the associated crystalline limestone as an intruded igneous mass, and the same method of origin was applied to the ores and accompanying so-called serpentine. The latter was called rensselaerite by Emmons. Brooks gave the following section, taken at the Caledonia Mine: 1„ Potsdam sandstone, 40 feet. 3. Hematites, 40 feet. 3. Soft, schistose, slaty, green, magne- sian rock with pyrite and graphite, 90 feet plus. 4. Granular, crystalline limestone, with phlogopite and graphite. 5. Sand- stone (like 1), 15 feet. 6. Crystalline limestone with beds and veins of granite. C. H. Smyth, Jr., has recorded the strati- graphical observations, cited earlier, and has formulated the following explanation of- origin. The lineal arrangement of the ore-bodies is referred to their association with a great stra- tum of pyritous gneiss belonging to the Oswegatchie Series. This weathers deeply and becomes light and porous (constitut- ' C. H. Smyth, Jr., "Geological Reconnaissance in the Vicinity of Gouverneur, N. Y.," Trans. N. Y.Acad. Sci., XII., 97, 1893. "Report on Jefferson and St. Lawrence Counties, " iJep. of N. Y. State Oeol., 1893, 493. Also 1895, 481. " See T. B. Brooks, Amer. Jour. Sci., iii., IV., 22. ^ J P. Kimball, Amer. Oeologist, December, 1891, p. 368. THE IRON SERIES CONTINUED. 125 ing thus a "fahlband"). It contains considerable dissemi- nated magnetite. The so-called serpentine or rensselaerite only occurs in association with ore, and itself varies in character, so that one is justified in regarding it as an altered form of several different kinds of rocks. Smyth infers that the decay of the ferruginous minerals, but especially of pyrite in the pyritous gneiss, has furnished the iron-bearing solutions, which following down the dip have replaced the crystalline limestone where the presence of intruded granites or the flattening of the dip checked the circulations. The action of the acidulated fer- ruginous waters has altered the granites and gneisses in the limestone series to the so-called serpentine.^ These views are fortified by microscopic study of the rocks, and though advanced only as, an hypothesis are worthy of great confidence. The mines have afforded in the past a moderately rich (50 to bb% Fe), non-Bessemer ore. The best known and largest producers are the Old Sterling, the Caledonia and Kearney properties, but they are not now operated and are not likely to be reopened in the immediate future. 2.02.14. Example 9. Lake Superior Hematites. Bodies of hematite, both red and specular, soft and hard, anhydrous and somewhat hydrated, associated with jaspers and cherts, and deposited by the replacement of cherty iron carbonate with iron oxide, in troughs, formed by some relatively impervious rock. The impervious rock is usually a decidedly altered igne- ous dike, now hornblendic and dioritic, but one that has been originally diabase. The trough may be formed by a folded dike; by two or more intersecting dikes; by the intersection of a dike and a compact, sedimentary stratum; or less commonly by a folded bed of slate. All of these varieties are known in one place and another. Increasing study has shown that the paral- lelism in the structure of the several districts, in the associates of the ore, and in the geological horizons at which the ore ' T. B. Brooks, " On Certain Lower Silurian Rocks in St, Lawrence Co., New York," Amer. Jour. Sci., iii., IV., p. 33. Eeo. G. S. Colby, Jour U. S. Assoc. Charcoal Iron Workers, XI. , p. 363. E. Emmons, N. Y. Oeol. Survey, Second District, p. 93. T. S, Hunt, " Mineralogy of the Lauren- tian Limestones of North America," 21st Ann. Rep. Regents N. Y. State Univ., 1871, p. 88. J. C. Smock, Bull. N. Y. State Mus., No. 7, 1889, p. 44. Rec. C. H. Smyth, Jr., in Report of N. Y. State Geologist for 1894, and Journal of Oeology, II., 678, 1894. Rec. <=^ - iL^ °V oa s /■'x. M m --P^ »a / ^^^ ) 1 j^^^ S^""""V ,_uyf^"**i. g^s f"^A~^ / 1 ■ - y^' / ^ L iW>++*^ «=B Vv^ ^^ — ^ 1 A / ^^-^ ^s ' 1 f i / -i \ CO h 0«3 <\ 'a ^ . tC3 V g^ ^ ^^r-'"^ s jS \i il?^l>= ^ > ** ||- Itf -0 '^ 3 Kl ^ Pi ^ I «-«««C r^ "^ ^ ** ^'^HfH+f rV\" N: Z ^ \ ^ v\ I C _/ **C / ..AW f ~ » Kn ^ riM' ! { ? < i ^ \ T**'^'K«t« 1 \ < -tj ** /A \°, ..v.«*^*V\ ;: O i \ "f^wlr^^ (' ^ ^ \ ^°C^^ \\^ vi 2 \ \ \ FW^^^^-V^ ) O \ '^ s ■^ J*. ^ \ / 1 1 ..uf'''^ 5J ■S^^>s^I>v ^^ 1 1 'i i^ f '^ 1 « /^ 1 ^'''^t4^^=-^^«l!^p •> g /> " 1- ^ '"^^ rx^,,^^ ; S J* 8 H ■w ^ t< w ? Hh _ J. ^ o ^ • ■*^ ■** 0. ^ ■■s ^ rs a «1^ ^ "S b I THE IRON SERIES CONTINUED. ] %1 occurs, is pronounced. Magnetite is at times present and limo- nites have been mined to a limited degree. There are five principal ore-producing belts or districts, which are also called in instances "ranges," as they follow ranges of low hills. They are, in the order of their chronological exploitation, the Mar- quette, just south of Lake Superior, in Michigan ; the Menomi- nee, on the southern border of the Upper Peninsula and partly in Wisconsin; the Gogebic or Penokee-Gogebic, on the north- western border between Michigan and Wisconsin; the Vermil- ion Lake, in Minnesota, northwest of Lake Superior; and the Mesabi (Mesaba), in the same general region as the last. 3.02.15. The geology of these districts has been a subject of much controversy, not alone in the relations of the separate areas, but in the subdivisions of a single one. The ever-pres- ent difficulty of classifying and correlating metamorphic rocks has here been very great. Moreover, there are other separate districts, of related geological structure, which ought also to be brought into harmony, and only at a very recent date has this been even partially attained. 2.03.16. The ores and their inclosing rocks have usually been called Huronian, as this is the name formerly applied to the schistose and metamorphic rocks overlying what was con- ceived to be the basal, gneissic Laurentian. The geologists of the United States Geological Survej' have essentially modified this nomenclature, and have restricted Archean to the earliest crystalline or metamorphosed, igneous rocks that precede the first sediments. Algonkian is then employed for the first and subsequent sedimentary rocks, and for the igneous intrusions that followed the first sediments up to the opening of the fos- siliferous Cambrian. The difficulty of correctly correlating these strata with the original Huronian prompted the step, but Huronian is still in very general use and Algonkian and the new meaning of Archean have received but moderate support outside of the Survey. In later years, however, the excep- tionally difficult geological problems in the iron ore districts on the south side of Lake Superior have been especially sojved by the geologists of the U. S. Survey, Irving, Van Hise, Bayley, H. L. Smyth, and others, and it is upon their work that the following descriptions for the three districts in question are based. The references in the footnote following will place any 128 KEMP-S ORE DEPOSITS. reader in toiich with the earlier literature, reviews of which will he foiind in the citations from Van Hise, A. Winchell and Wads worth.' The north shore districts are also closelj- related , and as a geological problem account must be taken as well of the original Huronian area, north of Lake Huron, and of the Kaministiquia and Rainy Lake regions north of Lake Supe- rior, although they contain no iron ores.'^ 2.02.1?. The oldest or pre-sedimentary rocks (Archean) consist of massive granites, gneissoid granites, syenites, perido- tites, greenstone schists, and other schists that are sheared and metamorphosed igneous rocks and tuffs of various kinds. Thej- were called the "Fundamental Complex" by Irving, and the name in the form of "Basement Complex" has been retained in the later work. Further investigation may clear up its stratigraphical relations to a certain extent. The Archean is succeeded by the formations of the Algonkian, which involve or succeed undoubted sediments. In the south shore iron ranges the Algonkian has been quite uniformly found to be divisible into two series, which are separated by an unconform- ity and a considerable period of erosion. The lower is called Lower Huronian, Lower Marquette, Keewatin, Lower Vermil- ion, and Menominee proper in the different exposiwes, and prob- ably the great cherty limestone of the Penokee-Gogebic series is its local equivalent. In the Marquette district Wadsworth has recently divided it still further into the Republic and Mes- nard formations. The upper part follows an unconformity and is called in the different regions tapper Huronian, Animikie, Upper Vermilion, Upper Marquette, Western Menominee, and ' C. R. Van Hise, "An Attempt to Harmonize Some Apparently Con- flicting Views on Lake Superior Stratigraphy, Amer. Jour. Soi., ii., XLI., 117; Tenth Annual Report Director U. S. Oeol. Survey. Van Hise, Bayley and Smyth, Monograph XXVIII. of V. S. Geological Survey on the Geology of the Marquette Iron District. A. Winchell, ' ' A Last Word with the Huronian," Bull. Oeol. Soc. Amer., II., 85. M. E. Wadsworth, " Notes on the Geology of the Iron and Copper Districts," 1880. '■ The following papers deal with the ores in general: D. N. Bacon, "The Development of Lake Superior Iron Ores," Trans. Amer. Inst. Min. Eng., XXVII., 341; John Birkinbine, "The Resources of the Lake Superior Region," Idem, XVL, 168, 1887; "The Iron Ore Supply," Idem, XXVII., 519: H. V. Winchell, "Historical Sketch of the Discovery of Mineral De- posits in the Lake Superior Basin," Proc. Lake Superiar Min. Inst., II., contains a bibliography. Se& also Amer. Geologist, XIII., 164. THE IRON SERIES COyTINCED. 129 Penokee-Gogebic proper. For the Marquette region this has also been further divided b}- Wadsworth into two, the Holj'oke and the Negaunee formations. It is mTich leps metamorphosed than the lower member, and in the Marquette district contains some ore. In the Menominee region of Wisconsin it affords the deposits there wrought and carries the ore in the Gogebic range. Higher in the section, after another unconformity fol- lows the Keweenawan (Keweenian) or Nipigon. This closes the Algonkian. Still above is the Cambrian (Eastern, West- ern or Potsdam) sandstone. 2.03.18. Example 9a. Marquette District, The Marquette —Generalized section across tlie Marquette Iron Raruje, to illustrate the type of folds. After G. R. Van Hise, Fifteenth Ann. Rep. Dir. U. 8. Geological Survey, p. 485. district was earliest known and has been most thoroughly stud- ied ; but owing to the confused geological structure, there has been, as already remarked, much discordance of interpretation. The remarkably careful and systematic work of Van Hise and Bayley^ has, however, cleared up the greatest diflBculties. In the Marquette district the Algonkian (or Huronian) rocks form a synclinorium or synclinal trough, resting in the older Archean crystallines and extending from Marquette on Lake Superior, westward in a nearly east and west line. While the axis of the main syncline runs east and west, there are many minor folds parallel with this, which are overturned outwardly from the 1 C. R. Van Hise and W. S. Bay ley, "Preliminary Report on the Marquette Iron-bearing District of Michigan," with a Chapter on the Republic Trough, by H. L. Smyth, Fifteenth Annual Report Director U. S. Oeol. Survey, 485-650. This report should be in the hands of every one interested in the region. See also Monograph XXVIII., which with its atlas is the fullest exposition of the subject. B \^ ■>•> H >> u >> s ■2 ^ a « y/. <^^ H v/, '=' -e CO ^ ■s « 5 ^K 3 ^1^ ^ s feN x>; XX XX XX 'fe-e 03 133 KEMP'S ORE DEPOSITS. center as in the accompanying figure, after Van Hise. Some marked folding has also occurred at right angles to the east and west axis. Faulting is almost entirely lacking, and the topographic relief is quite entirely due to the relative resist- ances presented by the several rocks to erosion. All are more or less metamorphosed and have evidently suffered severely from pressure and shearing stresses. The Lower Marquette is chiefly developed at the eastern end and around the rims of the synclinorium, as it was from this end that the shore-line seems to have advanced upon the ancient land. It begins with the Mesnard quartzite, 110 to 670 feet thick. Above come in order the Kona dolomite, 435 to 1,375 feet; the Wewe slate, 550 to 1,050 feet; the Ajibik quartzite, 700 to 900 feet; the Siamo slate, 300 to 635 feet; and the Negaunee iron formation, 1,000 to 1,500 feet. In Figs. 36 and 37 all these except the Negaunee are grouped under one sign. The total thickness varies from 2,975 to 6,130. The Upper Marquette includes from below upward, the Ishpeming formation, including the Goodrich quartzite and the Bijiki schist; the Michigamme formation of slates and mica schist; and the Clarksburg formation of more or less altered volcanic rocks. Upon Figs. 36 and 37 the Ishpeming has one sign and the Michigamme and Clarksburg another. In the mining district the total thick- ness of the Upper Marquette is less than 5,000 feet. Except as regards the Goodrich quartzite of the Ishpeming and some small limonite deposits in the Michigamme formation the divisions have no economic importance. In the Lower Marquette the economic interest centers in the Negaunee formation, which is much the most important of alL Later than all these just cited are intrusions of basic dikes that have been prime factors in the ore deposition. The Negaunee formation in its completest section consists from below upward of sideritic slate and griinerite-magnetite' slate; ferruginous slate; ferruginous chert ; and at the top of jasper ite or jasper- rock; but not all of these are necessarily present in any one section. The ores are either "soft ores" or "hard ores." The former are blue, red or brown, earthy and somewhat hydrated varieties of hematite, and resemble ordi- ' Griinerite is a variety of amphibole or hornblende. It is an iron amphibole. Fig. 29.— Open cut in the Republic mine, Marquette range, showing a horse of jasper. From a photograph by H. A. Wheeler. THE IRON SERIES CONTINUED. 133 nary dirt of these colors, with small lumps of ore scattered throughout. They strongly simulate, limonite but are not so hydrated. The soft ores are now the main object of mining, but they were earlier looked upon with disfavor and only the hard ores were sought. The hard ores are mas- ■•=»%•? W M -Hjife^ Mif^WftjLii^fl^ Fig. 28. — Cross-xrrtinttn to illustratr the occurrence and asxnn'ntb/ns of iron ore in the MarquMc district, Mirhigan. After ('. U. Vin, Uise, Amtr. Jour. Sci.. Febriiari/, 1893; Eiir/ineering and Miimig Journal. July 9, 1892. sive or micaceous specular hematite, rarely magnetite, and are blasted out in lumps. Van Hise makes three classes of depos- its: (]) Those at the bottom of the iron-bearing formation; (3) those within it; and (3) those at its top, including also some that rnn up into the Goodrich quartzite, the lowest stratum of 134 KEMP'S ORE DEPOSITS. the overlying Ishpeming formation. The hard ores belong to the third class. All these classes rest upon an impervious rock of some sort, and lie in a pitching trough formed by it. The trough may be a fold in the Siamo slate, and often is for ores of the first class. It may be a single folded dike, which is an altered diabase, now called soapstone or paint-rock by the miners. These are shown in the cuts of Fig. 28. The trough may result from the intersection of two or more dikes, as is more fully illustrated under the Vermilion district. In all cases it seems evident that after the close of the time-period rep- resented by the Upper Marquette, and after the intrusion of the basic dikes, the overlying ferruginous rocks were subjected to extensive leaching of their iron, by descending atmospheric waters, charged with carbonic acid. When these came to rest in the troughs, or met other descending currents, which were charged with oxygen, and which had percolated downward along the dikes, the dissolved proto-salt of iron was oxidized and precipitated as ferric oxide, replacing the cherts or other siliceous rock that had previously filled the trough. The sil- ica is thought to have been in large part removed by alkaline solutions emanating from the diabase. These changes were facilitated by the fact that the brittle cherts had been much shattered during the folding, and this condition contributed to the formation of the soft ores in their fragmental condition. The hard ores appear to owe their condition to the dynamic metamorphism that has been particularly strong along the con- tact line of the Upper and Lower Marquette. The micaceous ores certainly owe their strticture to shearing. The magne- tites are supposed to be former hematites, that have suffered partial reduction by infiltrating solutions charged with organic matter. They are best developed in the Republic tongue of the main trough. 2.02.21. The origin of these ore bodies has been a subject of much controversy. A review of the various hypotheses up to 1880 is given in Wadsworth's monograph' and a still later one is given in the monograph of Van Hise,Bayley and Smyth. ^ ' M. E. Wadsworth, "Notes on the Iron and Copper Districts of Lake Superior," Bull. Mus. Comp. Zool, Vol. VII., No. 1, July, 1880. ° Van Hise, Bay ley and Smyth, "The Marquette Iron-bearing District of Michigan," Monograph XXVIII. U. S. Geological Survey, pp. 3-148, 1897. THE IRON SMBIE8 OONTINUEB. 135 The early survey of Foster and Whitney (1851) attributed an eruptive origin to them and the same difficult thesis has been supported by Wadsworth (1880). Others formerly regarded them as old limonite beds in a sedimentary series that was subsequently metamorphosed. Credner (1869), Brooks (1873), and others saw reason for it; but there is little doubt that the origin outlined above is correct. While the present text follows the recent work of the U. S. Geological Survey, be- cause it is more detailed, comprehensive and really accurate than any other available, and because space is necessarily limited, yet the reader who would thoroughly acquaint him- self with the questions under discussion should consult the citations given below, especially those from Brooks, Irving, Wadsworth and Rominger. 2.03.33. It was in the forties that the importance and extent of the ore bodies were first vaguely suspected. The trouble that they made with the compasses of the early land surveyors indicated their existence. Important mining began in 1854. Somewhat over 100,000 tons were produced in 1860, over 800,- 000 in 1870, nearly 1,500,000 in 1880. In 1877 the Menominee region was opened, and in 1885 the Penokee- Gogebic and Ver- milion districts began to ship. The total shipments from the Lake Superior region in 1890 were 8,983,531 tons. The total production through 1897 of the Marquette district was 49,263,- 233 tons. A quite complete citation of the literature is to be found in Wadsworth's monograph, already referred to; in Irv- ing's "Copper-bearing Eocks of Lake Superior," Monograph v., U. S. Geol. Survey; and in Van Hise, Bay ley and Smyth, Monograph XXVIII. See also under Examples 9&, 9c, and 9d. Only the most important or most recent papers are mentioned here.' ' J. Birkinbine, "Resources of the Lake Superior District," M. E., July, 1887. T. B. Brooks, Oeol. Survey of Michigan, Vol I., 1873; Geol. Survey of Wisconsin, Vol. III., p. 450. H. Credner, "Die vorsilurischen Gebilde der oberen Halbinsel von Michigan in Nord Amerika," Zeitsch. d. d. Geol. Ges.: 1869, XXL. 516; also Berg- und Hutt. Zeit, 1871, p. 369. Foster and Whitney, Geol. of the Lake Superior District, Vol. I. , " Iron Lands, " 1851. R. D. Irving, "On the Origin of the Feriniginous Schists and Iron Ores of the Lake Superior Region," 4mer. Jour. Sci., iii., XXXII., 263; " Preliminary Paper on an Investigation of the Archean of the North- western States," Fifth Ann, Rep. Director U. S. Geol. Survey, p. 131; 136 KEMP'S OBE DEPOSITS. 2.03.23. Example 9fo. Menominee District. The Menomi- nee River, which gives the district its name, forms the south- easterly boundary between the Upper Peninsula of Michigan and Wisconsin. The mines are situated about forty miles south of the Marquette group, and the same distance west of Lake Michigan. The larger number are in Michigan, but the productive bolt extends also into Wisconsin. They lie along the south side of an east and west range of hills, which rises from 200 to 300 feet above the surrounding swampy land. Begin- ning with the base and included in the lower Menominee accord- ing to H. L. Smj'th, the geological section is as follows, all of Seventh A nn. Rep. , p. 431 ; also Administrative Reports in subsequent volumes. J. E. Jopling, "The Marquette Range: Its Discovery, Devel opment, and Resources," Trans. Amer. Inst. Min. Eng., XXVII., 541. J. P. Kimball, "The Iron Ore of the Marquette District," Amer. Jour, of Sci., it., XXXIX,, 390. H. S. Jlunroe, School of Mines Quarterly, II., p. 43. E. Reyer, " Geologie der Amerikanischen Eisenerzlagerstatten (insbe- sondeu Michigan)." Oest. Zeitsch. f. Berg- u. Hutt., Vol. XXXV., pp. 120, 131, 1887. C. Rominger, Geol. Survey of Michigan, Vol. IV., 1884. "Re- port on the Iron and CopiDer Regions, 1881-84, Idem, Vol. V., 1895. C. R. Van Hise, "An Attempt to Harmonize Some Apparently Conflicting Views of Lake Superior Stratigraphy," Amer. Jour. Sci., iii., XLI., p. 117, Feb- ruary, 1891; Tenth Arm. Rep. Director U. S. Oeol. Survey; ' The Iron Ores of the Marquette District of Michigan," Amer. Jour. Sci., February, 1892, p. 115. 15th Annual Report Director U. S. Geol. Survey, pp. 485- 657. Van Hise, Bayley and Smyth. " The Marquette Iron-bearing District of Michigan," Mono. XXVIII and Atlas U. S. Geol. Survey. M. E. Wadsworth, " Notes on the Iron and Copper Districts of Lake Superior," Bull. Mus. Comp. Zool., VII., 1, 1880; "On the Origin of the Iron Ores of the Marquette District, Lake Superior," Proc. Bost. Sac. Nat. Hist., Vol. XX., p. 470; Engineering and Mining Journal, Oct. 29, 1881, p. 386; Ann. Rep. Mich. State Geologist, 1891-93. "The Geology of the Lake Superior Region," in a pamphlet issued by the Duluth, South Shore & Atlantic R. R. , 1892. Dr. Wadsworth announces a new subdivision of Formations in this and in Amer. Jour. Sci., January, 1893, p. 73. H. "Wedding, Zeitsch. f. Berg-, Hiitt-, und Salinenwesen in Preus. Staat. , XXIV. , p. 389. C. E. "Wright and C. D. Lawton, Reps, of the Commissioners of Mineral Statistics of Michigan, 1880, and annually to date. G. H. "Williams, " Greenstone Schist Areas of the Menominee and Marquette Regions of Michigan," introduction by R. D. Irving, Bull. 62, U. S. Geol. Survey. H. V. "Winohell^' "Historical Sketch of the Discovery of Mineral Deposits in the Lake Supei'ior Region, Proc. Lake Superior Mining Inst , II. 3. A careful compilation of analyses of ores from all the larger mines of the four older ranges is given bj' Geo.'W. Goetz, Trans. Amer. Inst. Min. Eng., XIX., 59, 1890. THE IRON SERIES CONTINUED. 137 which rests on the Archean crystallines : 1. A basal quartzite, rareh- conglomeratic, 1,000 feet thick as a maximum, and at least TOO feet over wide areas. 2. A crystalline limestone, 700 to 1,000 feet thick, and possibly reaching 1,500 to 3,000 on the Fence River. This was earlier called by Rominger the Norway limestone. 3. Red, black and green slates that are not known to exceed 200 to 300 feet. The slates here and there contain the iron formation that affords the rich ores of Iron Mountain and Nor- way. In the southern portion the horizon of the slates is in part occupied by altered eruptives, which may thicken up to 2,000 feet on the Fence River. 4. The Michigamme jasper, a greatly altered ferruginous rock, usually carrying apparently Q^^ Fig. 30. — Plan of the Ludington ore hody, Menominee district, Michigan. After P. Larsson, Trans. Amer. Inst. Min. Eng., XVI., 119. fragmental quartz grains. The rock is best developed at Michi- gamme Mountain, S. 4, T. 43 N., R. 31 W. It is variable but appears to have originally been, in part at least, a clastic sedi- ment. Infiltrating iron salts and the formation of cherty sil- ica have brought about the alteration of the rock. Iron ores are met at three horizons in this section. The low- est is in the quartzite, No. 1, not far from its junction with the limestone. It has yielded but one workable deposit The great majority of the ore bodies is in the slates, No. 3. They occur as local concentrations, in a ferruginous rock composed of banded jasper and iron ore. The ferruginous rock is met at various horizons in the slates. The third ore-bearing forma- tion is the Michigamme jasper, but the ore bodies are small. ^ ' The above is condensed from H. L. Smyth, "Relations of the Lower Menominee and Lower Marquette Series in Michigan (Preliminary),'' Amer. Jour Sci. , March, 1894, 216. Further correlative notes are given in 138 KEMP'S ORE DEPOSITS. The Michigamme jasper is correlated by Smyth with the Negaunee formation of the Marquette district, and this brings the principal ore bearing stratum of the Menominee range below the ore- bearing formations in the Marquette. In the black slates of the Upper or Western Menominee there are still other ore bodies, such as those of the Common- wealth and Florence mines, and at the Quinnesec mines. A goodly mass of soft blue ore was obtained in the Potsdam sand- stone, which had evidently been eroded from the older ores during the deposition of the Potsdam. Great geologic interest has been felt in the metamorphism of the eruptive rocks in the Menominee district, and although remotely related to the geology of the ores, attention should be directed to the valua- ble paper of G. H. Williams cited below. Since 1890 W. S. Gresley of Erie, Pa., has been collecting from the ore piles in that city most extraordinary slabs of ore, chiefly from the Chapin mine, of the Menominee range, that contain impressions bearing the closest resemblance to algse, or other low forms of plant life. They may be the long-sought fossils of Huronian times. ^ The Menominee ores are generally soft, blue-earthy hema- tites, which give a red powder and consist of finely divided particles of specular. Brown hematites are very limited. A lenticular shape is more pronounced than in the Marquette district and the concentration of the ore has not been shown to be connected with intruded dikes as elsewhere, although the chemical reactions involved are doubtless the same. The gen- eral strike is about N. 75° W., and the dip 70° to 80° N. They also pitch diagonally down on the dip. (Cf. New Jersey Mag- netites, Example 13d.) There has been produced including 1897 a grand total of 21,931,441 tons since mining began. ^ C. B. Van Hise's paper on the Marquette range, in ISth Ann. Rep. Dir. U. S. Geol. Survey, p. 647. Smyth has also given an excellent short sketch at the close of his paper on "Magnetic Observations in Geological Mapping," Trans. Amer. Inst. Min. Eng., XXVI., 640-709, 1896. ' W. S. Gresley, "Traces of Organic Remains from the Huronian (?) Series at Iron Mountain, Mich.," etc., Trans. Amer. Inst. Min. Eng., XXVI., 527. See also Science, April 24, 1896, <^%^;Amer. Geologist, August, 1896, 123. ^ T. B. Brooks, Geol. Survey of Wisconsin, Vol. III., 430-663. D. H. Bi-own, "Distribution of Phosphorus in the Ludington Mine," M. E., XVI,: THE IRON SERIES CONTINUED. 139 Some fifteen miles north of the Menominee range, and between it and Negaunee in the Marquette range, is a narrow, closely folded syncline, called the Felch Mountain district. It contains a series of strata closely parallel to the Lower Menomi- nee, and apparently an outlier cut off by erosion. H. L. Smyth has also traced out by means of magnetic observations a northwesterly extension of the Menominee range, in a drift- covered district, so as almost to connect with the Marquette area west of the Republic' trough. From 30 to 30 miles of con- cealed rocks have thus been shown that may prove productive, although the cheap ores of the Mesabi range have made their immediate future uncertain.' 2.03.24. Example 9c. Penokee-Gogebic District. This lies in an east and west range of hills, which crosses the westerly boundarj' of the Upper Peninsula and Wisconsin, and is from ten to twenty miles south of Lake Superior, and eighty to one hundred miles west of the Marquette mines. The rocks are less metamorphosed than in the previous two districts. The strata run east and west with a northerly dip of 60° to 80° (65° in the larger mines), and with no subordinate folds. The geological series is now generally called the Penokee, following the usage of Irving and Van Hise, to whose labors we owe our accurate knowledge of the district and from whose papers the following is taken. It rests upon the southern complex of Archean crys- , tallines and forms a narrow belt, over 70 miles long, and from half a mile to three miles broad. The geological structure and relations are much simpler than in the other districts, and have afforded the key for the solution of problems elsewhere. The strata are divided into an upper and a lower series, of which the former is much the larger in amount, but the latter is the 525. J. Fulton, " Mode of Deposition of the Iron Ores of the Menominee Range, Michigan," Trans. Amer. Inst. Min. Eng., XVI., 535. N. P. Hulst, "The Geology of that Portion of the Menominee Range East of the Me- nominee River, Proo. Lake Superior Mining Institute. March, 1893, p. 19. Per Larsson, " The Chapin Mine," Trans. Amer. Inst. Min. Eng., XYI., 119. C. E. Wright, Geol. Survey Wisconsin, III. ,666-734. G. H. Williams, " Greenstone Schist Areas of the Menominee and Marquette Regions of Michigan, with an Introduction by R. D. Irving," Bull. G3, U. S. Oeol. Survey. ' H. L. Smyth, "Magnetic Observations in Geological Mapping." Trans. Amer. Inst. Min. Eng., XXVI., 640, 189 6. THE IRON SERIES CONTINUED. 141 one that is of economic importance. At the base is a cherty dolomitic limestone 300 feet and less thick. It outcrops chieflj' at the extreme west and the extreme east, and has no immedi- ate connection with the ores. Over this lies a quartz-slate or quartzite that is extremely persistent throughout the entire aroa. It is 500 feet and less thick, and forms the usual foot- wall of the large ore bodies. Ahove the quartz slate is the iron-bearing member, 800 to 1,000 feet thick. It is not clastic, but consists of cherty carbonates of iron, with some magnesium and calcium, or of derivatives from these carbonates and cherts. Three types of rock have been established: (1) The slaty and often cherty iron carbonate, more or less analogous to siliceous iron carbonates in the Carboniferous and other later systems. It is regarded as of organic origin. (2) Ferruginous slates and cherts. The iron of the siderite in type one has been more or less moved and redeposited as oxides, and rearrange- ment and recrystallization of the silica have also transpired. (.3) ActinoTite and magnetite schists have resulted by the Change of much of the iron carbonate to magnetite and bj: the combination of the remainder with lime, magnesia and silica to yield actinolite. This last-named type is especially abun- dant west of Tyler's Fork, i.e., in the western third and beyond the productive raining region. The upper Penokee consists of slate, with quartzites, graywackes and schists, 12,800 feet thick and less. It has no connection with the ores, and is suc- ceeded by the Keweenawan traps and sandstones on the north. All the Penokee strata are cut by dikes and sheets of diabase, some of which in the iron-bearing formation have played an important part in the production of the ore bodies. The ores are found in the lower portion of the iron-bearing member, and either on or near the underlying quartz-slate. .The northerly dipping quartz-slate with the overlying cherty carbonates and ferruginous slates is cut by southerly dipping diabase dikes, so as to form a trough with sides nearly at right angles. The troughs themselves pitch downward to the west, and in them, as illustrated by the accompanying figures (Figs. 32 and 33) are found the ore bodies. The ores are soft blue, brown and black earthy hematites, and often contain notable percentages of manganese. There is little doubt that they have been derived from the cherty carbonates in the overlying iron- U2 KEMP'S ORE DEPOSITS. s I' *> •) a !:, fcf 'a e -« ?? &- ^ ^=? s !^ ts" S § ►i; -s g 'f^ ~ 5^ f^ ■y ^ ►c 3 "&> 09 ^ S ? 3 « IS r^ •e H s a: ■n,^ * ^,^- T s Cl g ■S s gl ^ 1 ?# 1 > < M rr si? d 6 THE IRON SERIES CONTINUED 143 bearing formation, which in the long run of weathering and erosion has yielded its iron oxide to descending atmospheric waters, more or less charged with carbonic acid. The iron- bearing solutions filtering downward have come to comparative rest in the troughs, where they have met other waters, presumabl}' charged with oxj-gen. The iron oxide has been precipitated and at the same time the silica has been removed by carbonated waters or by those which have been rendered alkaline by the leaching of the neighboring dikes. The latter are excessively altered and are locally called soapstone or soap-rock in description of their condition. It is impossible to state how much of the iron-bear- FlG. 33. — Gross-section of the Colby mine, Penokee-Gogebic district, Mich- igan, to illustrate occurrences and origin of the ore. After C. It. Van Rise, Amer. Jour. ScL, January, 1891. ing formation has disappeared in the protracted process of super- ficial erosion, but probably some thousands of feet. The depth to which the ore will be found in the troughs is also problemati- cal. It is now known to extend to 800 feet on the dip. The solution of the question of the origin of these ores has been one of the most valuable of the additions to our knowledge in recent years, and has proved suggestive and fruitful for all the other Lake Superior districts. The range became productive in 1885, and including 1897 there has been shipped a total of 33,047,023 tons of ore.' ' C. M. Boas, Some Dike Features of the Gogebic Iron Range," TVans. Amer. Inst. Min. Eng., XXVII., 556. R, D. Irving, Oeol. Survey of Wis- 144 KEMP'S ORE DEPOSITS. 2.02.35. Example 9d. Vermilion Range, Minnesota. Bodies of hard specular ores at Vermilion Lake, and soft ores at Ely, deposited in troughs as in the preceding examples, formed by folded or intersecting dikes, which penetrate the iron-bearing formation. The district is situated in north- eastern Minnesota, and lies northwest from Lake Superior. Two Harbors, the shipping point, is twenty-six miles east of Duluth, and from Tower, the principal town near the Vermil- ion Lake mines, it is sixty-seven miles to the docks. Ely is twenty-three miles northeast of Tower. Leaving the lake the railroad first crosses with heavy grades the northwestern flank of the Lake Superior synclinal, chiefly consisting of the south- easterly dipping trap sheets of the Keweenawan. Underlying these is a series of gabbros and augite syenites — the former of which contain some titaniferous magnetites, similar to those in the Adirondacks. The Mesabi range of hills succeeds on the north, but although ore-bearing further west, as described under the next example, it is barren at this point, and consists chiefly of black slates, referred to the Animikie. Sedimen- tary, gneissic and eruptive rocks, regarded as Laurentian by the Minnesota geologists, succeed, and give place finally to the metamorphic rocks of the Vermilion range, that contain the ore. Still further north are the Laurentian rocks again. This whole region needs further and very detailed mapping to accu- rately bring out its geological structure, although the main points mentioned above serve to outline it. The immediate geological relations of the ores have been elucidated, however, by the recent careful work of H. L, Smyth and J. R. Finlay, consin, 111., pp. 100-167, 1880. "Origin of the Ferruginous Schists and Iron Ores of the Lake Superior Region," ^??ier. Jour. Sci., iii., XXXII., 363, 365; see- also under Van Hise. C. D. Lawton, "Gogebic Iron Mines," Engineering and Mining Journal, Jan. 15, 1887, p. 43. C. R. Van Hise, " On the Origin of the Mica Schists and Black Mica Slates of the Penokee- Gogebic Iron-bearing Series," Amer. Jour. Sci.., iil, XXXI., 453-459. "The Iron Ores of the Penokee-Gogebic Series in Michigan and Wisconsin, Amer. Jour. Sci.. iii., XXXVII., 33. Irving and Van Hise, "ThePenokee Iron-bearing Series of Northern Michigan and Wisconsin," Monograph XIX. , U. S. Geological Survey, 1893. Rec. An abstract of the monograph will be found in the Tenth Annual Rep. Director U. S. Oeol. Survey, 341. Rec. G. Whittlesey, "The Penokee Minei'al Range, Wisconsin," Proc. Host. Soc. Nat. Hist., IX., July, 1863. C. E. Wright, Geol. Survey of Wisconsin, III., pp. 339-301. THE IRON SERIES CONTINUED. 145 Fig. 34. — Map of the Minnesota. Iron Ranges. After F. W. Denton, 'Iroms. Amer. Inst Min. Eng., KXVII., 344. 146 KEMP'S GBE DEPOSITS to which the subsequent description is chiefly due. For a thorough reading up upon the district, the references given below will suffice/ The Vermilion Lake mines are situated on the top of an abrupt hill above the town of Soudan. Some ore appears in Lee Hill, a mile or two southeast, near Tower, but the depos- its are not knoM'n to be large. The mines at Soudan extend for about a mile along a main belt in a direction a little north of east, and upon a more or less parallel minor belt that lies a short distance north. This alignment is due to the intrusion of a great mass of greenstone, with many ramifying dikes, but all on this general line, which is also the strike of the jasper. On the northern side of the mines the surface slopes some- what sharply to Vermilion Lake. The general relations are illustrated by the accompanying Fig. 35. Smytb and Finlay have shown that stratigraphically there are two series of sedi- mentary rocks, both of which have been penetrated by abun- dant intrusions of quartz porphyry and diabase. The lower series consists of slates and graywackes, not excessively meta- morphosed. The slates are at times carbonaceous and occa- sionally charged with pyrites. Above the slates lies the iron- bearing formation, consisting of quartz, variously intermingled with hematite or magnetite, or quite free from either. The ' A. H. Chester, Eleventh Ann. Rep. Minn. Oeol. Smvey, 155, 167. T. B. Comstock, " Vermilion Lake District in British America," Trans. Amer. Inst. Min. Eng., July, 1887; F. W Denton, " Methods of Iron Mining in Northern Minnesota,' Idem, XXVII., 344. R. D. Irving, Seventh Ann. Rep. U. S. Geol. Survey, 1885-86, 435. H. L. Smytli and J. R, Finlay. ' ' The Geological Structure of the Western Part of the Vermilion Range, Minnesota," Trans. Amer. Inst. Min. Eng., XXV., 595-645, 1895. Rec. C. R. Van Hise, Bull. 86, U. S. Oeol. Survey. Various references in chap- ter ii. Bailey Willis, Tenth Census, XV., 457. Alexander Winchell, Fif- teenth Ann. Rep. Minn. Geol. Survey, 174. Also "Some Results of Archean Studies," Bull. Oeol. Soc. Amer., 1, 357. H. V. Winchell, "Diabasic Schists, Containing the Jaspilyte Beds of Northeastern Minnesota," Amer. Oeol, II., 18. "The Iron Ranges of Minnesota," Proo. Lake Superior Mining Inst., III., 1895. Rec. N. H. Winchell: Many references to the region by N. H. Winchell are to be found in the reports of the Minn. Geol. Survey. They are practically summarized in the next reference. N. H. and H. . V. Winchell, " The Iron Ores of Minnesota," .Bi^H. 6, Geol Survey of Minn. Rec. "On a Possible Chemical Origin of the Iron Ores of the Kewatin in Minnesota," ^4 mer. Geol. TV., 291, 389. "The Taconic Iron Ores of Minnesota and Western New England," Amer. Oeol, VI., 263. 148 - KEMP'8 ORE DEPOSITS. varieties occur in parallel but narrow bands, never over three or four inches across, and doubtless represent the original beds of the sediment, but just what the character of the origi- nal sediment was, whether the cherty carbonates of the south shore or the probable glauconites of the Mesabi range is hope- lessly destroyed by metamorphism. These sediments each form three belts, as shown in Fig. 35, which are repeated because of sharply compressed and pitching folds. After the formation of the sediments, but before the folding, intrusions of quartz porphyry and diabase took place, as dikes and sheets, some large, others of excessive thinness. Subsequently all suffered severely from compression. A larger series of folds was developed along an east and west line, and a smaller series at right angles to this. This severe compression and shearing changed the quartz porphyries in large part to conglomerate breccias, and to sericite' schists, while the diabases passed into chlorite or actinolite schists or conglomerate breccias. The breccias first resulting from the crushing have had their frag- ments so rubbed upon one another that they are stretched and rounded_and have their interstices filled with sericite schist or chlorite schist, as the case may be. The brecciationtook place on the anticlinal crests, but in the synclinal troughs schists resulted. These foldings also formed troughs especially from the corrugated green.stone dikes and from the intersections of the same, and when the iron- bearing formation stood over such a trough, it passed through the same series of changes that have been earlier outlined under the Marquette range, so that the iron oxide became concentrated along the sides and on the bot- toms, while the silica was removed. The accompanying fig- ures exhibit cross-sections in all respects like those on the south shore. The ores are all hai'd, dense, specular, and are about half of bessamar and half of nou-bessemer grade. 2.02.26. The geological relations at Ely are practically the same, but the ore body as displayed in the Chandler and Pioneer mines is larger than at Vermilion Lake. It rests, however, on a' greenstone dike, which is folded into a syncline with a minor roll in the bottom of the trough which, as shown in Fig. 38, makes it a double one. The ores are soft hematites of extraor- dinary richness and purity, and are all of very high bessemer grade. Indications of ore are strong still further east, and Fig. 37. — Open cut at Minnesota Iron Company's Mine, Soudan, near Tower, in south view looking west. Photograph by J. F. Kemp, 1894. liiw? 'V U^''" ''*X('''"'-"^-'J' ^^i;;^£_>; 'iQ^5u.Ji^l 5a •s GO en al « tti 8':S-<*A<': Si s, !^ *-:; T-l •■^ >n ^4 ^ tx H ?; N C>- ,s &9 e « I 150 KEMP'S OBB DEPOSITS. developments have now proved important. The combined output of the mines at Ely and Vermilion Lake is from 800,000 to over 1,000,000 tons annually, about equally divided between them. The total shipments up to the close of 1897 have been 10,498,716 tons.' The work of H. L. Smyth and Finlay has demonstrated what many observers have felt from more cursory examination — ■ that the geological relations of these ores are essentially the same as those on the south shore. Different explanations have, however, been advanced, and great uncertainty has surrounded the geology, on account of the excessively metamorphosed and -Horizontal and vertical cross-sections of the Chandler ore body at Ely, Minn. After Smyth and Mnlay, Trans. Amer. Inst. Min. Kng., XXV., 595, 1895. obscure igneous rocks. N. H. and H. V. Winchell have argued that the ores were submarine precipitates from volcanic lapilli, furnished by submarine eruptions. From , the lapilli the sea water was thought to have extracted the iron and silica. There seems, however, little reason to question the results of Smyth and Finlay. 3.02.37. Example 9e. Mesabi Range. Of much more recent development than the other districts is the Mesabi range of Minnesota. The mines began to make important shipments of ore in 1893. The indications are that the depos- its are not less extensive than those in any other of the Lake THE IRON 8EBIE8 CONTINUED. 151 Superior localities, and that they are even larger and of a char- acter to be more easilj' mined. The present developments are situated southwest of Vermilion Lake, and nearer Duluth and Lake Superior. They cover a stretch of about 30 miles, from Biwabik on the east, through McKinley, Virginia, Eveleth, Mountain Iron and smaller towns to Hibbing on the west. Little ore is known beyond Hibbing. The ore bodies are all south of the granite ridge. The ore lies under the black slates called Animikie in the section given in Paragraph 2.02.25, and over the quartzite, there called the Pewabic; but they are situated twenty miles or so west of the line of that section. The Fig. 40. — -O-eneral cross-section of ore body at Biwabik, Mesabi Range, Minn. After H. V. Winchell, Twentieth Atm. Rep. Minn. State Geologist. ore bodies are all south of the granite ridge called the Giants' Range. Upon the southern slopes of this range lie the green schists of the Keewatin, which are unconformably overlain by the Pewabic quartzite. On this rests the ore-bearing rock, which is a jaspery or cherty siliceous variety called taconyte by H. V. Winchell. Over this, in order, come greenish siliceous slates and cherts, black slates (referred to the Animikie), and great masses of gabbro. On the flanks of the Giants' Range the dip is steep, but it flattens out nearly to horizontality away from the granite. All the formations above the Keewatin are called Taconic by the Winchells. 152 KEMP'S ORE DEPOSITS. 2.02.28. The ore bodies lie on tiie southerly slopes of low hills, and are found immediately helow the mantle of glacial drift, which varies up to 200 feet in thickness. Ore indications have long been known on the range, and various reports have been made in former years, although always unfavorably. The indications then available showed only siliceous limonites of low grade. Deep test pits, however, which penetrated these caps and the drift, have revealed enormous ore bodies and have rewarded persistent prospecting. The ores are blue and brown and of soft, earthy texture, with occasional hard streaks. They lie from 10 to as much as 180 feet below the surface as now mined, and where the stripping is suflSciently thin it is removed with steam shovels, and then after being shaken up with black powder the ore is excavated in the same way. The ore bodies are lenses, which at times, as at the Mesaba Mountain or Oliver mine in Virginia, appear to form a basin. In the central part of this mine a drill hole is stated to have shown 335 feet of ore, but the general run is less. The ore bodies have usually a southeasterly trend, and are longer than wide. The blue ores are richest in iron and purest as regards phosphorus, and they are the ones specially desired. Ores for foundry iron also occur in large amount, but are at present less sought for. The rock most intimately associated with them all is the chert, called taconyte. The underlying quartzite is occasionallj- shown in the mines as well as the overlying slates, but the whole region is so completely buried in drift that outcropping rock is a rare thing. The ores are thought by H. V. Winchell to have originated bj' replacement of the taconyte. The rock contains calcareous streaks which have perhaps aided in furnishing the carbonic acid, which, it is thought, has dissolved the silica of the taconyte in the replacement process. Recently, valuable observations on the geology of the ores have been accumulated by J. E. Spurr, while in the field for the Minnesota Geological Survey, in whose Bulletin X. the detailed report has appeared. A preliminary paper in the American Geologist for May, 1894, gives an abstract of the results. As in the Penokee-Gogebic and Marquette districts, the western end of the Mesaba range is least disturbed and metamorphosed. The stratigraphy is the same as that already outlined in preceding paragraphs, but the ^ si OC Jl ^ I i5^ '8 •S e « &9 s 1 1 « 0) « ■?- g .5? ^^ s 'a-i ^ "fe- THE IRON SERIES CONTINUED. 153 quartzite is simply called by Spurr, Animikie, and not Pewa- bic. The iron-bearing series is stated to be from 500 to 1,000 feet thick, with an average of 800 feet. The unaltered rock is described as consisting of "cryptocrystalline, chalcedonic or finely phenocrystalline silica" thickly "strewn with rounded or subangular bodies made up chiefly of a green mineral," regarded as glauconite, the hydrated silicate of protoxide of iron and potash. Analyses of the rock corroborate this deter- mination, because they indicate a constant but small percent- age of potash. Layers of the rock, rich in calcite (probably magnesian) also occur. Spurr is thus led to regard the rock as an altered greensand, to which view similar conclusions regard- ing the much more recent and unmetamorphosed ores of Texas and Louisiana (see 3.01.15) give support. The chemistry of the deposition is considered by Spurr to be the following: Atmospheric waters, with dissolved carbonic acid, and some alkaline salts have filtered into the cracks and become charged with ferrous carbonate, where the conditions prevented oxidation. The greater solubility of the ferrous salt led to its solution before the alkali attacked the silica. Later, reaching more open and fissured portions, the ferrous salt was oxidized and deposited, while the silica was attacked and removed by the alkali. In time, thus the iron oxide was concentrated along fissured strips, near faults, and the like, whereas the silica was removed. It is recognized as well that the ferrous salt was precipitated as carbonate, amid deoxidiz- ing conditions. The change from silicate or carbonate to hydrous oxide of iron led to shrinkage and shattering, and the passage from hydrous oxide to carbonate, where such occurred, to expansion and shattering. It follows from the explanation that the regions of rich ore bodies would be those of notable geological disturbances, so that faults are presumed near Vir- ginia, Biwabik and elsewhere.' ' C. E. Bailey, "Mining Methods on the Mesabi Range," Trans. Amer. Inst. Min. Eng., XXVII., 539. F. W. Denton, "Open-pit Mining with Special Reference to the Mesabi," Proc. Lake Superior Mining Inst., III., 1896. "Methods of Iron Mining in Northern Minnesota," Trans. Amer. Inst. Min. Eng., XXVII., 344. E. P. Jennings, "The Mesabi Range," Sci- ence, XXIII., 73. E. J. Longyear, "Explorations on the Mesabi Range," Trans. Amer. Inst. Min. Eng., XXVII., 537. J. E. Spurr, " The Mesabi 164 KEMP'S ORE DEPOSITS. 2.02.29. Hematites apparently much like those of Lake Superior have been reported from the Hartville iron district in Laramie County, Wyoming. The ores, according to W. C. Knight, constitute irregular zones in Carboniferous rocks and are associated in many cases with copper deposits. (See 2.04.28.) The published analyses show rich ores of bessemer grade. ^ 2.02.30. The explorations of Mr. A. P. Low, of the Geologi- cal Survey of Canada, have shown extensive developments of iron carbonates, and magnetite and hematite, associated with jasper, and with cherty Carbonate of lime, along the east side of Hudson Bay, and in the valleys of the Koksoak (called also Ungava) and Hamilton rivers. Mr. Low describes the enclos- ing strata as Cambrian. The samples brought back proved rather low in iron (30 to 54% Fe), but the geological relations are extraordinarily like those of Lake Superior.^ 2.02.31. Example 10. James Eiver, Virginia. Specular hematite in narrow beds (lenses), interstratified with quartzites and slates of metamorphic character and Archean age. They run four to six feet, or less, in thickness, with prevailingly vertical dip, but they also pitch diagonally down on the dip like the lenses of magnetite, later described. They furnish a very excellent grade of ore. The ore bodies are found along both sides of the James River, a few miles above Lynchburg. Some magnetite also occurs in the region, and some limonite. More or less clay accompanies the ore.^ Iron-bearing Rooks," BttZfeii»iO, Minn. Geol. Survey, 18Qi- Eec. "Thelron Ores of the MesabJ Range," Ame7: Geologist, XIII., May, 1894, 335. H. V. Winchell, Twentieth Ann. Rep. Minn. State Oeol. , 112, 1892. ' ' Iron Ores of Minnesota," Bull. 6, Minn. Oeol. Survey. H. V. Winchell and J. T. Jones, "The Biwabik Mine," Trans. Anier. Inst. Min. Eng., XXI., 951. For an early account of the Mesabi Range see New York Times, December 14, 1892. ' W. C. Knight, Bulletin 14., Wyoming Experiment Station, Laramie, Wyo., pp. 135 and 176. A large series of analyses appears in the prospec- tus of the Wyoming Railway and Iron Co. E. P. Snow, "The Hartville Iron Ore Deposits in Wyoming,'' Engineering and Mining Journal, Octo- ber 5, 1895, p. 330. ' The above note is due to the courtesy of Dr. George M. Dawson, Di- rector of the Geological Survey of Canada, who kindly gave the writer an abstract of Mr. Low's report in advance of its publication. = E. B. Benton, Tenth Census, Vol. XI., p. 363 (on Virginia). J. L. Campbell, Geology and Resources of the James River Valley, p. 49, New THE IRON SElilES CONTINUED. 155 2.02.33. Similar lenses of specular ore and magnetite are foimd in central North Carolina, in schistose rocks, which have been referred to the Huronian. As stated under 2.02.29, lenses of specular hematite of very excellent quality are found also in metamorphic rocks, north of Fort Laramie, Wyoming, which may prove productive in time. 2.02.33. Example 11. Pilot Knob, Missouri. Two beds of hard specular hematite separated by a thin seam of so-called slate (possibly volcanic tuff), and interstratified with breccias and sheets of porphyry. Along the eastern limit of the Ozark uplift of Missouri and Arkansas a series of knobs of granite and porphyritic rocks project through the Cambrian limestones and sandstones. They are older than, the limestones, and clearly were not intruded through them. The limestones and sandstones lie up against the porphyry and in the valleys between. The underlying porphyry has been found in the val- ley near Pilot Knob, after penetrating four hundred feet of sedimentary rocks. The porphyry and ores have often been called Huronian, but in view of the recent reorganization of the Huronian (see Example 9), this is not done, nor ever has been, on any accurate grounds. Pilot Knob is formed by one of these eruptive knobs. It consists of sheets of porphyries that are capped by porphyry breccia, and two ore beds, and the in- tervening slaty rock which may be a tuff. The beds strike and dip 13° S. S. W. The hill is over 600 feet high. The lower bed has furnished most of the ore, running from 25 to 40 feet thick, and affording a dense bluish, specular hematite of from 50 to 60%" Fe, siliceous and very low in phosphorus. The Kipper bed is irregular and of lower grade, and runs from 6 to 10 feet thick. The Pilot Knob mines in this solid ore are now substantially exhausted. Eeceut drill holes on the northerly slope and below the out- cropping face of ore have shown that under the Cambrian strata of the valley there is a great bed of ore boulders or breccia in clay, much as is the case at Iron Mountain, later described. Analyses of these latter ores were not, however, York, 1882. H. B. C. Nitze, "On North Carolina," Bulletin No. 1, North Carolina Geol. Survey, 1893. B. Willis, Tenth Census, Vol. XV., p. 301. The Virginias, a monthly, formerly published by Jed. Hotchkiss, at Staun- ton, contains much information on Virginia in general. 1»»W»BW, e THE IRON 'SERIES CONTINUED. 157 sufficiently encouraging for development during the recent low prices for iron. Doubtless the bed will afford important re- serves. 2.02.34. Near Pilot Knob are two other hills of porphyry, Shepherd Mountain and Cedar Mountain, whose ores are structurally more related to Example 11a. The first contains three veins, the Champion, the North, and the South. They are long and narrow (4 to 10 feet) strike north 60° to 70° east, and dip 70° north. The Champion vein contained a little streak of natural lodestone, but the ore is mostly specular. The North vein shows a good breast of ore five feet wide, but too full of pyrite to be available. Cedar Mountain has a vein of specular ore. Neither hill has been an important pro- ducer. Minor veins have been found on neighboring porphyry hills (Buford, Hogan, and Lewis mountains), some of which contain much manganese. 2.02.35. Example 11a. Iron Mountain, Missouri. Veins of bard, specular hematite irregularly seaming a knob of por- phyry. Iron Mountain is five or six miles north of Pilot Knob, and is a low hill with a westerly spur called Little Mountain. It has also a northerly spur. It consists of feldspar porphy- ries, more or less altered. These are seamed with one large, and on the west somewhat dome-shaped, parent mass of ore and innumerable minor veins that radiate into the surrounding rock. Upon the flanks of the porphyrj' hill rests a mantling succession of sedimentary rocks, that dip away on all sides. The lowest member is a conglomerate of ore fragments, weath- ered porphyry, and residual clay left bj' its alteration. It is regarded by Pumpellyas formed by pre-Silurian, surface disin- tegration and not bj' shore action, inasmuch as sand does not fill the interstices, while white clay from decomposed porphyry does. It is, however, overlain by a thin bed of coarse, friable sandstone, which marks the advance of the sea, and whose formation preceded the limestones. This conglomerate was in later years the principal source of the ore, but the mines are now considered to be worked out. It was mined underground, hoisted and washed by hydraulic methods, like those employed in the auriferous gravels of California, and then jigged. The apatite has largely weathered out of it. The rock of the mountain itself, in the cuts of the mines, is largely kaolinized,' 168 KEMP'S OHE DEPOSITS. and exhibits everywhere the effects of extreme alteration. The smaller veins that penetrate the porphyry show at times casts or much altered cores of apatite crystals. 2.02.36. The porphyries of Pilot Knob and Iron Moun- tain, in thin section, are seen to belong to quartz porphyries, feldspar porphyries, and porphyrites. Both orthoclase and plagioclase are present in them, and many interesting forms of structure. One significant fact is that they are everywhere filled with dusty particles of iron oxide, probably magnetite. An eruptive' origin was originally assigned to these ores by J. D. Whitney {Metallic Wealth of the United States, p. 479, 1854), just as to the Lake Superior hematites. The later in- vestigations of Adolph Schmidt for the Missouri Survey in 1871 arrived at a different conclusion. Dr. Schmidt considered them, whether occurring in an apparent bed, as at Pilot Knob, or in various more or less irregu lar veins, as at Iron Mountain, to have been formed either by a replacement of the porphyries with iron oxide deposited from solution, or by a filling in the same way of fissures, probably formed by the contraction of the porphyry in cooling. In the valuable report on iron ores by F. L. Nason in the Missouri Geological Survey a sedimentary origin is advocated for the Pilot Knob beds. Thej' are con- ceived to have been deposited in a body of water in a hollow, between formerly existing porphyry hills, which rose above. In the course of weathering, the hills became the valleys, and the early sedimentary beds the hilltop. It is, however, some- what difficult to understand how the more or less incoherent sediments withstood degradation better than the hard, firm, porphyry hills. Some such origin as sedimentation or replace- ment is, however, the only reasonable one. It is not improba- ble that the Pilot Knob ores originated in the saturation and more or less complete replacement of layers of tuffs with in- filtrating iron oxide. An extended table of analyses of Iron Mountain ores will be found in Mineral Resources of the United States, 1889-90, p. 47.' ' G. C. Broadhead, "The Geological History of the Ozark Uplift, "^me?-. Oeol., Ill , 6. J. E. Gage, "On the Occurrence of Iron Ores in Missouri," Trans. St. Louis Acad. Sci., 1873, Vol. III., p. 181. E. Harrison, "Age of •the Porphyry Hills, Ibid., Vol. II., p. 504. E. Haworth, "A Contribu- Fig. 43. — View of open cut at Pilot Knob, Mo., showing the bedded char- acter of the iron ore. From a photograph by J. F. Kemp, 1888. o a* e § 6 l-H THE IRON SERIES CONTINUED. 159 ANALYSES OF HEMATITES, RED AND SPECULAR. (The same discrimination must be employed in looking over these anal- yses that was emphasized under limonite. ) Fe. P. S. SiO,. Al.Oe HjO. Clinton, N. Y. (fossil ore) 44.10 51.7.") 44.40 51.03 .56 40 0.650 1.392 0.115 0.345 0.230 12.63 5.45 2.77 Pennsylvania (MiflHin ore) Tennessee (Meigs County) 0.028 0.340 0.883 0.085 0.530 0.067 0.009 0.040 0.015 0.139 0.020 16.80 0.50 Antwerp, N. Y 46.32 59.41 68.40 64.83 60.47 65.50 .59 15 Missouri (Crawford County) Marquette dist., Mich, (specular) Menominee district, Michigan. . . "d.bio 2.07 3.60 3.38 5.75 13.27 3.03 Pilot Knob Mo 3.19 James River (Maud vein) Elba 49.89 61.81 70.00 0.170 5.97 3.47 Pure mineral These analyses are mostly taken from State reports and froln Mineral Resources of the United States. They are intended to illustrate he general run of compositions, but for Birming- ham and Marquette are high. Analyses vary widely. tion to the Archaean Geology of Missouri," Artier. Oeol., I., 280-363; "Age and Origin of the Crystalline Rocks of Missouri," Bull. 5, Mo. Oeol. Sur- vey, 1891. A. V. Leonhard, "Notes on the Mineralogy of Missouri," Trans. St. Louis Acad. Set, Vol. IV., p. 440. F. L. Nason, "Report on the Iron Ores of Missouri," Mo. Geol. Survey, II. Rec. R. Pumpelly, "Geology of Pilot Knob and Vicinity," Mo. Geol. Survey, 1872, p. 5; see also remarks on Iron Mountain, Bull. Geol. Soc. Amer., Vol. II., p. 230. Rec. W. B. Potter, "The Iron Ore Regions of Missouri," Journal U. S. Asso. Charcoal Iron ]V'orkers, Vol. VI., p. 23. Rec. F. A. Sampson, "A Bibliography of the Geology of Missouri," Bull. S, Mo. Oeol. Survey, 1890. (This is a valuable book of reference. ) F. Shepherd, Ann. Rep. Mo. Geol. Survey, 1853-54. Hist. A. Schmidt, "Iron Ores of Missouri," Mo. Geol. Survey, 1872, p. 45, and especially p. 94. Rec. J. D. Whitney, Metallic Wealth of the U. S., p. 479. Of more recent issues are the followmg: E. Ha worth, "The Crystalline Rocks of Missouri," Eighth Ann. Rep. Mo. Oeol. Survey, 1894, p. 81. C. R. Keyes. "Geographic Relations of the Granites and Porphyries in the Ea.stern Part of the Ozarks," iJjttt. Geol. Soe. Amer., VII., 363, 1896. " Report on the Mine la Motte Sheet," Oeol. Survey of Mo., IX., ,Sheet Report 4. Arthur Winslow^ E. Haworth and F. L. Nason, "Report on the Iron Mountain Sheet," Idem, Sheet Report 3. Rec. This last is the best work of reference as regards the mines. Further details will be found in Winslow's Bulletin 132 of the U. S. Oeol. Survey, on "The Disseminated Lead Ores of Southeastern Missouri." CHAPTEE III. MAGNETITE AND PYRITE. 2.03.01. Example 12. Magnetite Beds. Beds of magne- tite, often of lenticular shape, interfoliated with Archean gneisses and crystalline limestones. They are extensively developed in the Adirondacks, in the New York and New Jer- sey Highlands, and in western North Carolina. The presence of magnetite in Michigan (Example 9a), in Minnesota (Exam- ple 66), on Shepherd Mountain in Missouri (Example 11), and in Virginia (Example 12) has already been referred to. Other magnetite bodies are known in Colorado, Utah, California and Wyoming, and will be mentioned subsequently. Titanium is often present, but the titaniferous ores are made a special exam- ple. The same is true of pyrite and pyrrhotite. Apatite is always found, although it may be in very small quantity. Chlorite, hornblende, augite, epidote, quartz, feldspar, and a little calcite are the common associated minerals. In New Jersey the beds occur in several parallel ranges or belts. 2.03.02. Example 12a. The Adirondacks. Deposits of magnetite are extensively developed in the -crystalline area of the Adirondacks, and they show some interesting relationships between the character of the ore and the nature of the country rock. The titaniferous varieties to be later described favor the interior, mountainous core, but the nontitaniferous are especially found on the flanks and in the foothills. The i^gion is in large part an eruptive area of plutonic rocks representing various members of the great gabbro family whose chief minerals are labradorite and some form of pyroxene. There are members which are little else than labradorite and which are called anorthosites ; there are others containing labradorite andhyper- sthene, the norites; still others are dark and basic, and consist MAGNETITE AND PTBITE. 161 of little else than labradorite, augite, hypersthene, ilmenite and garnets, the last-named having been formed by metamor- phism.^ Augite syenites of massive character have recently been recognized by H. P. Gushing, and the discovery has thrown much light on many rocks only known before as gneisses. All these eruptives have suffered greatly from dyna- mic metamorphism, and are now as a rule decidedly gneissoid in structure. In addition to the eruptives there are white, crys- talline, graphitic marbles, usually charged with pyroxenes; black, hornblendic schists; quartzites; and quartzose gneisses that represent a series of sedimentary rocks of Algonkian age, but that are now much broken by the eruptives above mentioned. The Algonkian sediments are most satisfactorily exhibited on the western side of the mountains. ' The general geology of the Adirondacks is described by E. Emmons in his "Report on the Second District of New York," N. Y. Natural History Survey, 1842. The later papers of importance are the following, and a general review of work that had been done up to 1892 is given by J. F. Kemp, ' ■ A Review of Work Hitherto Done on the Geology of the Adiron- dacks," Trails. N. Y. Acad, of Sciences, XII., 19, 1892. H. P. Cvishing, "Re- port on the Geology of Clinton Co.," IJthAnn. Rep. State Geologist, 1893, 473; 15th Idem,, 499. "Report on the Boundary Between the Potsdam and Pre-Cambrian Rooks North of the Adirondacks," 16th Annual Report State Geologist, 1896. An additional report on Franklin Co. is in press (1899). "Augite-syenite Gneiss near Loon Lake, N. Y.," Bull. Geol. Soc. Amer , X., 177-193. J. F. Kemp, " Gabbros on the Western Shore of Lake Champlain," /dent, V., 213, 1894. "Crystalline Limestones, Ophicalcites and Associated.Schists of the Eastern Adirondacks," Jdejd, VI., 241. "Pre- liminary Report on the Geology of Essex Co.," Rep. N. Y. State Geologist for 1893, 79, 1894; continued in the 15th Ann. Rep.. Idem, 1895, 575. A report on Warren Co. is in press. "The Geology of Moriah andWestport Townships, Essex Co.," Bull. N. Y. State Museum, III., 325, 1895. "The Geology of the Magnetites near Port Henrj', N. Y., Trans. Amer. Inst. Min. Eng. , XXVII. , 146, 1897. ' ' The Geology of the Lake Placid Region, " Bull. N. Y. State Museum, V., 51, 1898. C. H. Smyth, Jr., "A Geological Reoonnoissance in the Vicinity of Gouverneur, N. Y. , Trans. N. Y. Acad. Sci.. XII., 203, 1893. " Petrography of the Gneisses of the Town of Gouv- erneur, N. Y.," Idem, XII., 308, 1893. "Report on the Geology of Four Townships in St. Lawrence and Jefferson Counties," 13th Ann. Rep. N. Y. State Geologist, 491. ■Crystalline Limestones and Associated Rooks of the Northwestern Adirondack Region," Bull. Geol. Soc. Amer., VI., 263, 1893. "Report on the Crystalline Rocks of St. Lawrence Co.," 15th Ann. Rep. N. Y. State Geologist, 1895, 477. Additional reports on the western Adirondacks are in press. le-Z KEMP-8 O&E DEfOSITS. 2.03.03. The magnetites are found in the form of lenticular masses that correspond perfectly to the foliation of the gneisses. They may extend long distances on the strike, as at Lyon Mountain, where the Chateaugay ore is said to be traceable four or five miles, but it is lean over most of the distance. Belts more or less continuous for a mile are opened up in several places. The ore may be in gneiss that is practically quartz and microperthite as at Hammondville; or in pj'roxenic gneisses as at Lj'on Mountain; or on the contact of gneiss like that which forms the wall-rock at Hammondville just mentioned, and dark, basic, hornblendic gneiss, derived from intruded gabbro; or on the contact of gabbro like the last and gneisses which are involved with crystalline limestones, as at the Chee- ver mine; or finally, in the crystalline limestones near gabbro intrusions, as at the Weston mines, Keens Center. The ores at ma Feet Fig. 47. — Crosa-sectmi of the Checoer iron, mine, near Port Henry, N. T., showing the occurrence of the ore in pyroxene gneiss, just over gabbro. Lake Ghamplain terminates the section at the rigid. After ,7. P. Kmp, Bull. N. Y. State Museum, Vol. III., p. 346. Mineville have been regarded as contact deposits by J. F. Kemp, and as having been developed by the neighboring gab- bro. As will appear from the accompanying map and sections, Figs. 48 and 49, there are two groups of mines. One on Bar- ton Hill is based on a long series of pods or lenses that occur between an underlying gabbro and gabbro-gneiss, and an over- lying gneiss, called the Orchard. The Orchard gneiss con- sists almost entirely of quartz and oligoclase. Above it is the Barton gneiss, containing some quartz with abundant micro- perthite, plagioclase, orthoclase, brown hornblende, augite and hypersthene. The lower group embracing the Miller pit. Old Bed and "21," have the "21" gneiss, an aggregate of quartz and microperthite, exposed on the surface. Diamond drill cores have, however, revealed the gabbro-gneiss beneath the ore in depth. The map brings out the parallel pod-like shape of the Fig. 46. — Vic2b of open cut and underground vorJ: in Mine 21, Mineville, near Port Henry, N. Y. Fliotograplied by J. F. Kemp, 1892, MAGNETITE AND PTBITE. 163 Fig. 48. — Ueological map of the iron mines at Minenlle, near Port Henry, N. T. For details of formations see text. After J. F. Kemp, Trans. Amer. Inst. Min. Eng., XX VII., 146. 164 KEMP'S ORE DEPOSITS. ores. In one instance, the New Bed mines, the workings have followed a pod over 2,000 ft. The magnetites have not yet been described in the same detail at other localities, but data araat hand which give ground for similar inferences regarding several additional ones. Gabbros are usually in the vicinity of the ore even when it does not occur on the contact. Never- theless some mines give no immediate evidence of the influence of any rock except that of the walls, as for instance the Palmer Hill workings near Ausable Forks; and the ore appears to be a great, basic segregation, drawn out into a band, parallel BATtan Onclss Orchjira QodJa '/yMA,/4r, Fig. 49. — Cross-section of ore-bodies at Minemlle, near Port Henry, N. Y., to aeeompany map, FiG. 48. After J. F. Kemp, Trans. Araer. Inst. Min. Encj., XXV IL, 146. with the foliation. At Palmer Hill the walls are a siliceous gneiss, consisting of quartz, microperthite, microcline and augite. The ores follow all the foldings and flowing curves that are exhibited in the foliation of the gneisses, and because of this they exhibit man}- peculiar shapes. They swell and pinch, roll and fold and feather out. Still, at Mineville they show a marked parallelism in the long axes of the pods or lenses, and while these tongue out into the walls, they do so with a gen- eral parallel alignment. Faults are common and in instances have sharply cut off the ore. Dark, brecciated strips may mark MAGNETITE AND PTBITE. ]65 the fault line and may resemble trap dikes, as in No. 7 slope at Hammondville. Small gulches are frequently over the places where the ore is lost, and serve to mark the fault line. Trap dikes are frequent in the mines, and hardly a solitary one fails to show them. They may fault the ore for a few feet.^ 3.03.04. In their metallurgical relations the ores may be clas- sified, following the example of B. W. Putnam in his report for the Tenth Census, into (1) those high in phosphorus, but low in sulphur (Mine 21, Mineville); (2) Bessemer ores, low in both phosphorus and sulphur (Barton Hill mines, Hammond- ville mines); (3) pyritous ores (Buck Mountain, Ticonderoga). ' The following papers relate especially to the ores as distinguished from the geology: L. C. Beck, Mineralogy of New York, Part I., 1-38, 1843. J. Birkinbine, " Crystalline Magnetite in the Port Henry (N. Y.) Mines,'' Trans. Amer. Inst. Min. Eng., XVIII., 747, 1890. Rec. "Note on the Magnetic Separation of Iron Ore at the Sariford Ore-bed, Moriah, Essex Co., N. Y., 1852, Idem, XXI., 378, 1892; see also p. 157. H. Credner, Zeitseh. d. d. g. Gesell, 1869, XXI., p. 516; B. and H. Zeit., 1871, 369. J. D. Dana "On the Theories of Origin," Amer. Jour. Sci., iii., XXII., 152, 402. E. Emmons, Geology of New York, Second District, pp. 87, 98, 231, 255, 291, 309, 350. Hist. C. E. Hall, "Laurentian Magnetite Ore Depos- its of Northern New York," 3:.'d Ann. Rep. State Museum, 1884, p. 133. Rec. Hanns Hoefer, "Die Kohlen- und Eisenerzlagerstatten Nord Amer- ikas," 175, 1878. J. F. Kemp, "Notes on the Minerals Occurring ne;ir Port Henry, N. Y.," Amer. Jour. Sci., iii., XI., 62, and Zeitseh. f. Kryst., XIX., 183. "The Geology of the Magnetites near Port Henry, N. Y," Trans. Amer. Inst. Min. Eng., XXVI., 146, 1897. G. W. Maynard, "The Iron Ores of Lake Champlaiu," Brit. Iron and Steel lust.. Vol. I., 1874. F. L. Nason, "Notes on Some Iron-bearing Rocks of the Adirondack Mountains," Amer. (Jeotogrist XII., 25, 1893. B.T.Putnam "Notes on the Iron Mices of New York, " Tenth Census, XV. , 89, 1885. Rec. B. Silliman, "Remarks on the Magnetites of Clifton, St. Lawrence County, N. Y.," Trails. Amer. Inst. Min. Eng. , I. , 364. J. C. Smock, ' ' Iron Mines of New York," Bull. VII., N. Y. State Museum. Rec. J. Stewart, "Laurentian Low Grade Phosphate Ores,'' Trans. Amer. Inst. Min. Eng.. XXL, 176, 1892. Wedding, Zeitschr. f. B., H., und S. im. p. St., XXIV., 330, 1876. See also the general works on Iron Ores cited at beginning of Part II. On Canadian magnetites the following papers may be mentioned: F. P. Dewey, "Some Canadian Iron Ores," Trans. Amer. Inst. Min. Eng., XII., 192. B. J. Harrington, "On the Iron Ores of Canada," Can. Geol. Survey, 1873- 74. T. S. Hunt, Can. Geol. Surrey. 1866-fi9, pp. 261, 262. T. D. Led- yard, "Some Ontario Magnetites," Trans. Auier. Inst Min. Eng., XIX., 28, and July, 1891. W. H. Merritt, "Occurrence of Magnetite Ore De- posits in Victoria County, Ontario," Froc. Amer. Asso. Adv. Sci., XXXI., 413, 1882. IfiG KEMP'S ORE DEPOSITS. On the western side of the mountains some extensive mining has also been done. The Benson mines at Little Eiver are based upon a broad, mineralized zone whose ore is inclined to be lean, and to be a subject for magnetic concentration. There are numerous deposits of magnetite in Canada, to the north of Lake Ontario, whose geological relations are similar to those above described. 2.03.05. Example 126. New York and New Jersey High- lands, and the South Mountain of Pennsylvania. Lenticular or pod-like masses of magnetite in Archean gneiss and crystalline Fk;. 50, Fig. 51. Figs. 50 and 51. — ytudii of the Tilly Foster ore body. 50. Side mew, sJiow- ing fiiuUed sliutilflcr. .-ifter F. S. Ruttmann, Trans. Amer. Inst. Mill. Eiiy., XV., 79. 51. View of bottom of same. Photo- gi-aplied by ./. F. Kemp from the model now at the School of Mines, Columbia College. limestone. From Putnam County, New York, a ridge of Archean rocks runs southwest across the Hudson River, trav- ersing Orange County, New York, and northern New Jersey, and running out in Pennsylvania. Lenses of magnetite occur throughout its entire extent. They are not as large as some in the Adirondacks, but they are more regularly distributed. East of the Hudson, in Putnam County, the Tilly Foster mine is the most important, and the descriptions and MAGNETITE AND PYEITE. 167 figures of it are the best illustrations of the shape of lenses published. West of the Hudson,' in Orange Countj-, the Forest of Dean mine affords considerable ore yearly. It is cut by an interesting trap dike. As the results of study of the Archean of this region, N. L. Britton has divided it into a Lower Massive group, a Middle Iron Bearing, and an Upper Schistose. {Geol. of N. J., 1886, p. 77.) F. L. Nason has also sought to classify it on the basis of rock types, of vphich he makes four, named, from their typical occur- rences, Mount Hope type, Oxford type, Franklin type, and Montville type. They are arranged in their order of probable age. They correspond in some respects to Britton's grouping, but differ materially in others. {Geol. of N. J., 1889, p. 30.) Four courses, or mine-belts, have been recognized in New Jer- sey — the Ramapo, the Passaic, the Musconetcong, and the Pequest— in order from east to west. The lenses strike north- east with the gneisses, and usually have, like them, high dips. In addition they have also a so-called "pitch" along the strike, so that they run diagonallj' down the dip. They have been observed to pitch northeast with an easterly dip and southwest with a westerlj-. Either by the overlapping of lenses or by an approximation to an elongated bed, they sometimes, as at Hibernia, extend a mile or more in unbroken series. Again, they may be almost circular in cross section (Hurd mine). At Franklin Furnace one is found in crystalline limestone.' ' E. S. Breidenbaugh, " On the Minerals Found at the Tilly Foster Mine, New York," Amer. Jour Sci., iii., VI., 207. J. F. Kemp, " Diorite Dike at the Forest of Dean Mine," Idem, iii., XXXV., 331. F. H. McDowell, "The Reopening of the Tilly Foster Mine," Trans. Amer. Inst. Min. Eng., XVII., 758; Engineering and Mining Journal, Sept. 7, 1889, 306. F. S Ruttman, " Notes on the Geology of the Tilly Foster Ore Body, Putnam County, New York," Trans. Amer. Inst. Min. Eng., XV., 79. Rec. J. C. Smock, Bull. VIL, N. Y. State Museum. Rec. A. F. Wendt, "The Iron Mines of Putnam County," Trans. Amer. Inst. Min. Eng., XIII., 478. " Iron Mines of New Jersey," School of Mines Quarterly, iv., III. N. L. Britton, Ann. Rep. N. J. Survey, 1886, p. 77. Rec. G. H. Cook and J. C. Smock, Oeol. of N. J., 1868. Rec. (See also subsequent annual reports, especially 1873, p. 13.) F. L. Nason, Ann. Rep. N. J. Survey, 1889. Rec. J. W. Pullmann, " The Production of the Hibernia Mine, New Jersey," Trans. Amer. Inst. Min. Eng., XIV., 904. J. C. Smock, "The Magnetite Iron Ores of New Jersey," Idem, II., 314; "A Review of the Iron Mining Industry of New Jersey," Idem, June, 1891. Rec. 168 KEMP'S ORE DEPOSITS. J. E. Wolff has contributed a very importaBt and suggestive paper upon the large bed of magnetite at Hibernia. The ore extends for about one mile as developed, and forms a persist- ent band in a series of gneisses which under the microscope are found to contain quartz, orthoclase, plagioclase, microcline, tnicroperthite, brown or green hornblende, a deep green or color- FlG. 52. — Sketch nip,p illustratiiig the geological structure of the Hibernia mag- netite bed, Hibernia, N. J. The ore outcrops for one mile. Ajter J. E. Wolff, Annual Report of the State Geologist of New Jersey for 1893. less augite, sometimes diallage, biotite, sometimes hypersthene, and as accessories, apatite, magnetite, and zircon. The dark silicates may form intermittent bands bj' their greater abund- ance, but are of no stratigraphic value. All the large minerals are in elongated spindles, whose long axes correspond to the pitch of the gneiss. They are thought by Wolff to have as- MAGNETITE AND PTRITE. 169 sumed this shape in crystallizing, during metamorphism. About a half mile from the ore and parallel with it is a band of biotite-garnet-graphite gneiss that is persistent, and that is folded as shown in Fig. 52. This latter rock is supposed to be a metamorphosed limestone, and the whole series is regarded as metamorphosed sediments by Wolflf.' F. L. Nason has worked out the structural geology of the Ringwood mines, and has found that they are quite well interpreted as lying along a pitching series of folded gneisses./ 2.03.06. South Mountain, Pa. Small lenses of magnetite occur in Berks, Bucks, and Lehigh Counties of southeastern Pennsylvania, in the metamorphic rocks of the South Moun- tain belt. They are very like those to the north in New Jer- sey, but are lower in both iron and phosphorus. Their product has reached 100,000 tons yearly. The Cornwall magnetite is described under Example 13, for its geological structure is entirely different from the lenses.^ 2.03.07. Example 12c. Western North Carolina and Vir- ginia. Beds of magnetite, of the characters already described, in Archean gneisses and schists. The ore body at Cranberry, N. C, is the largest and best known. It occurs in Mitchell County, and has lately been connected by rail with the lines in east Tennessee. According to Kerr, the principal outcrop is 1,.500 feet long and 200 to 800 feet broad ; but, of course, this is not all ore. The mines can afford very large quantities of excel- lent Bessemer grade. Pyroxene and epidote are associated with the ore. Kerr has referred the magnetite to the Upper Lauren- tian. In the southern central portions of North Carolina other magnetites occur in the mica and talcose schists, which have been referred to the Huronian. (See H. B. C. Nitze, Bull. /., N. C. Geol. /Swrfe?/, for detailed report.) (Example 10.) Magnetite has also been lately reported from Franklin and ' J. E. Wolff, " Geological Structure in the Vicinity of Hibernia, N. J., and its Relation to the Ore Deposits,' N. J. Geol. Survey, 1893, 359. ^ F. L. Nason, '■ The Geological Structure of the Ringwood Iron Mines, N. J.," Trans. Amer. Inst. Min. Eng., XXIV,, 505, 1894. ' E. V. d'Invilliers, Rep. D3, Penn. Survey, Vol. II. (South Mountain Belt of Berks County) . Reo. F. Prime, Rep. D3, Vol. I., Pe»iM. Swruej/ (Lehigh County). B. T. Putnam, Tenth Census, Vol. XV., p. 179. 170 • KEMP'S ORE DEPOSITS. Henry Counties, Virginia, and Stokes County, North Carolina. Some doubt, however, is cast on its amount and qualitj'.' 2.03.08. Example 13d. Colorado Magnetites. Beds of magnetite of a lenticular character in rocks described as sye- nite (Chaffee County) and diorite (Fremont County). With these a number of others are mentioned which vary from the example, but of which more information is needed before they can be well classified. The last are mere prospects. The mines in Chaffee County have been the only actual producers. There are three principal claims — the Calumet, Hecla and Smithfield. They extend continuously over 4,000 feet. The wall rock is called syenite. Chauvenet describes them as having resulted from the oxidation of pyrites, and as being in rocks of Silurian age. They average bl% Fe, with only 0.009 P, but are comparatively high in S, reaching 0.1 to %.0%. These mines and those at the Hot Springs, mentioned under Ex- ample 2, have furnished the Pueblo furnaces with most of their stock. The deposit in Fremont County is at Iron Moun- tain, but is too titaniferous to be valuable. It is a lenticular mass in olivine-gabbro, and is again referred to under 2.03.11. A large ore body has been reported from Costillo County, in limestone (Census Eeport) or sj'enite (Rolker). In Gunnison County, at the Iron King and Cumberland mines, excellent ore occurs in quartzites and limestones, called Silurian. At Ashcroft, near Aspen, high up in the northern side of the Elk Mountains, is a great bed or vein of magnetite in limestones of Carboniferous age with abundant eruptive rocks near. It is thought by Devereux to be altered pyrite. Still, pyrite is a common thing with magnetite elsewhere. There are other smaller deposits in Bowlder County, and elsewhere in the State.^ ' H. S. Chase, "Southern Magnetites and Magnetic Separation," Trans. Amer. Inst. Min. Eng., XXV., 551-557, 1896. W. C. Kerr, Geology of North Carolina, 1875, 264. J.P.Kimball, " On the Magnetite Belt at Cranberry, N. C," etc., Amer. GeoL, XX., 399-312, 1897. H. B. C. Nitze, " Notes on the Magnetites of Southwestern Virginia and the Contiguous Territory of North Carolina," Trans. Amer. Inst. Min. Eng., XX., 174, and discussion, 185. "The Magnetic Iron Ores of Ashe Co., N. C, Idem, XXI., 260. " Magnetic Iron Ore in Granville Co., N. C," Eng. and Min. Jour., April 33, 1892, p. 447. B. Willis, Tenth Census, XV., 325; Eiig. and Min. Jour., Jan. 7, 1888. Kerr and Hanna, " Ores of North Carolina," 1893. " E. Chauvenet, "Papers on Iron Prospects of Colorado," 4wn. Heps. Colo. State School of Mines, 1885 and 1887 ; also Trans. Amer. Inst. Min. MAGNETITE AND P TRITE. 171 2.03.09. In Wyoming an immense mass of titaniferous mag- netite is known near Chugwater Creek. It is more fully described under Example 13, with which type of ore body it belongs. 2.03.10. Examplel2e. California Magnetite. Bedsof mag- netite of lenticular shape in metamorphic slates and limestones on the western slope of the Sierra Nevada. Others of different character are also known. In Sierra and Placer counties lenses of excellent ore are found, accompanying an extended stratum of limestone in chlorite slate. A great ore body of magnetite described as a vein has lately been reported from San Bernard- ino County. It is said to be from 30 to 150 feet thick, and to lie between dolomitic limestone and syenite.' A great bed of a kind not specified is reported from San Diego County.^ 2.03.11. Example 13. Masses of titaniferous magnetite in igneous rocks which are most often gabbros or related types. General comments were made upon these in 1.06.14 and 1.00.16. In many cases such ore bodies seem undoubtedly to be exces- sively basic segregations of fused and cooling magmas. Whether the tendency of these early crystallizations to concentrate is due to Soret's principle, to magnetic currents or attractions, or to the high specific gravity of the mineral which might cause it to sink in the magma, is perhaps not alwaj's clear, for all these explanations have been suggested. The masses are not yet of practical value in North America, and hence are not, strictly speaking, ores; but no one familiar with their size and amount can resist the conviction that they will ultimately be utilized. The commonest rocks forming the walls are gabbros, norites, diorites or peridotites, all of which are close relatives. Later metamorphism, such as mountain-making processes and the Eiig., Denver meeting, 1889. Rec. W. B. Devereux, " Notes on Iron Prospects in Pitkin County, Colorado,' Trans. Amer. Inst. Min. Eng., XII,, 608. B. T.Putnam, Tenth Census, Vol. XV., p. 472. Rec. C. M. Rolker, "Notes on Iron Ore Deposits in Colorado," Trans. Amer. Inst. Min. Eng., XIV., 266. Rec. ' Ann. Rep. State Mineralogist, 1889, p. 235. " Ibid., 1889, p. lo4. J. R. Browne, "Mineral Resources West of the Rocky Mountains," 1868. C. King and J. D. Hague, " Miner-al Resources West of the Rocky Mountains," 1874, p. 44. H. G. Hanks and W. Irelan, Ann. Reps. State Mineralogist, California. (Very little on iron. ) F. von Riohthofen, private reports quoted in Tenth Census, Vol. XV., p. 49.5. J. D, Whitney, Geul. Survey of Cal., Vol. I. 172 KEMP'S ORE DEPOSITS. like, sometimes give the wall rock a gneissic structure and stretch out the ore into apparent beds. The ores have some characteristic peculiarities of chemical and mineralogical com- position. As a rule, although not invariably, they are low in sulphur and phosphorus. On analysis they almost always afford small percentages of vanadium, chromium, nickel and cobalt. They may be so rich in alumina and magnesia as to indicate the presence of spinel. In fact, one variety of these ores, that is found near Peekskill, N. Y., and at Routivara, in Sweden, is an aggregate of spinel and titaniferous magnetite. Ores of this variety show genetic relations with some deposits of emery and corundum. The pig iron afforded by the tjtanif- erous ores has certain excellencies peculiar to itself that may be due to one or more of the above ingredients.' Many years ago T. S. Hunt recognized the fact that the titaniferous ores of Canada and the Adirondacks were limited to the labradorite rocks of the Norian or Upper Laurentian series. It is now known that they may occur both in anor- thosites and in basic gabbros. The ore-bodies are of enormous size on the lower St. Lawrence (Bay St. Paul), on the Sague- nay River, and near Lake Saudford, in the heart of the Adiron- dacks. Smaller, but still very large masses, are known in Que- bec, north of Montreal; in Ontario, north of Kingston; in West- port and Elizabethtown, N. Y., and in several other places not far from the national boundary.^ ' Tlie chemical characters are discussed by J. F. Kemp in a paper on "The Titaniferous Iron Ores of the Adirondacks," Nineteenth Ann. Rep. Dir. U. S. Geol. Survey, Part III. , p. 377. A detailed review of titanifer- ous ores the world over, by the same writer, will be found in the School of Mines Quarterly. July and November, 1899 . All the analyses known to be piiblished to date are compiled. ^ On the Canadian ores see: F. D. Adams, " Ueber das Norian oder Ober-Laurentian von Canada, Neues Jahrbuoh, Beilage Band. VIII., 410; an English translation will be found in the Canadian Record of Science, 1894, 169; 1895, Jan., p. 1, July, p. 1. "On the Igneous Origin of Certain Ores, " Proc. General Mining Association of the Province of Quebec, Jan. 13, 1894. E. J. Chapman, "On Some Iron Ores' of Central Ontario," Trans. Royal Soc. of Can., 188.5, 9. See also Idem, 1884, 159, R. W. Ells, Geol. Survey of Canada, 1888-89, 14K, B. J. Harrington, Idem, 1873-74, 237. T. S. Hunt, Idem, 1847, ,59; 1867, 213. F. J. Pope, "Titaniferous Ores of Ontario," Trans. Amer. Inat. Min. Eng., May, 1899. On the ores in New York see: E. Emmons' Report on the Second District, N. Y., State Survey, 244, 1842. J. F. Kemp, "The Titaniferous Iron Ores of the Adi- MAGNETITE AND PTBITE. 173 The ores near Peekskillare low m titanic oxide, not ranging above four per cent., but they are extremely rich in alumina, and attention was first directed to them by J. P. Kimball, on account of this ingredient. They constitute excessively basic developments in the norites of the Cortlandt series of gabbroic rocks, that cover about twenty-five square miles on the Hudson River. They are also present as small, separate dikes. They consist of spinel, magnetite, corundum, garnet and occasional sillimanite, and are remarkably close parallels with some results of artificial experiments obtained by Josef MOrozewicz. They have been utilized for emery and are near relatives in a geo- logical way to some deposits of corundum and emery.' A very curious and interesting knob, or boss, of peridotite is exposed -at Iron Mine Hill, Cumberland, R. I., that is so en- riched with titaniferous magnetite as to receive attention as an ore. It protrudes through mica schists and is closely akin to the Swedish one at Taberg, as was recognized many years ago by M. E. Wadsworth.' A belt of titaniferous ores traverses New Jersey and affords magnetites of moderate percentages of TiO^.' Several belts rondacks," Nineteenth Ann. Rep. Director U. S. Oeol. Survey, 377, 1899. Also Fifteenth Ann. Report of N. Y. State Geologist, 608, 1898. G. W. Maynard, "The Iron Ores of Lake Champlain," Jour. Brit. Iron ami Steel Inst., 1874. A. J. Rossi, "Titaniferous Ores in the Blast Furnace. " Trans. Amer. Inst. Min. Eng., XXI., 832, 1893. " The Smelting of Titan- iferous Ores," The Iron Age, Feb. 6 and 30, 1896. ' J. D. Dana, Amer. Jotvr. Sci. Further notes by G. H. "Williams, Rlent, Feb., 1887, 194. J. P. Kimball, Amer. Chemist, IV., 1874, 321 ; Trans. Amer. Inst. Min. Enc/., IX., 19, 1880. Their geological relations will be more fully described in a forthcoming paper bj' J. F. Kemp and M. B. Yung. On the artificial production of these ore mixtures, see Josef Morozewicz, Tschermaks Min. u. Petr. Mitth., "On the Related Swedish Ores." W. Fetterson, Geol. Foren. in Stockholm Forhandl, XV., 45, 1893. Hj. Sjogren, Idem, .5.") and 140. ' M. E. Wadsworth, " Lithological Studies," Bull. Mus. Comp. Zool. Harvard College, VII. , 1881, 183. A later note will be found in the Bulletin Amer. Iron and Steel Association, Nov. 20, 1889. See also, A. L. Holley, Trans. Amer. Inst. Min. Eng., YI., 224, 1877. C. T. Jackson, Geological Survey of Rhode Island, 53, 1840. N. S. Shaler, Sixteenth Ann. Rep. U. S. Geol. Survey, II., 321. Bull. Mus. Comp. Zool., Harvard College, XVI., 185. B. Willis, Tenth Census, XV., 567. ' On New Jersey, see the Annual Reports of the State Geologist as follows: 1873, ,53, 55; 1875, 35; 1.H76, 54; 1877, 49; 1878, 99, 100; 1879,62, 67, 76; 1880, 125. R. W. Raymond, Trans. Amer. Inst. Min. Eng., XXI., 174 KEMP'S ORE DEPOSITS. occur in North Carolina.' The wall rocks have not been as yet accurately determined in either State. In th'e extreme northeastern corner of Minnesota, on Mayhew Lake, and at other points within the huge area of gabbros in this State, the ores are known, and some small amount of work has been expended on them.^ Titaniferous ore has been described by Arnold Hague as forming great dikes in granite on Chugwater Creek, Wyo. Olivine-gabbro and anorthosite are in the neighbor- hood, and have been determined as the wall rock of at least one mass of ore by B. F. Hill.' The rock was collected by W. G. Knight. The ores are also known in at least three places in Colorado. One is in Fremont County, at the so-called Iron Mountain, which is situated about fifty miles west of Pueblo, in the Wet Mountain valley, on a tributary of Grape Creek. A sample 6i rock believed to have come from the walls has been determined by J. F. Kemp to be an olivine-gabbro.* An- other locality is Caribou Hill in Boulder CountV:^ and a third 1892, 275. B. F. Faokenthal, Idem, 279. Isidor Walz, Amer. Chemist, June, 1876, 453. The Church mine on Schooley's Mountain is the best known one. ' On North Carolina,, see North Carolina Oeol. Survey, II., 1893, 181. J. P. Lesley, "Notes on the Titaniferous Iron-ore Belt near Greensboro, N. C," Proc. Amer. Phil Soc, XII., 1871, 139. H. B. C. Nitze, Bulletin I., N. C. Oeol. Survey. Bailey Willis, "On the Dannemora Mine," Tenth Census, XV., 310. ' W. S. Bay ley, "Peripheral Phases of the Great Gabbro Mass of North- eastern Minnesota," Jour. Oeol., Vol. I., p. 818. See also, for notes on their petrography. Idem, Vol. III., p. 1. C. R. Van Hise, Bull. Oeol. Soc. Amer. , VII. , 1895, 488. N. H. Winohell, Tenth Ann. Rep. Minn. Oeol. Survey, 1882, 85. N. H. and H. V. Winohell, Bulletin VI. .Idem, 186. M. E. Wadsworth, Bulletin II , Idem, 63, 73. ^ Arnold Hague, U. S. ,Oeol. Explor. Fortieth Parallel, II., 12, 1877. F. V. Hayden, U. S. Oeol. and Oeogr. Survey, Territories, 1870, 14. B. F. Hill, School of Mines Quarterly, July, 1899. W. G. Knight, Bull. XIV. Wyo. Agric. Experiment Station, 177, 1893. Howard Stansbury, Ex- ploration and Survey of the Valley of the Oreat Salt Lake, 1852, 266. F. Zirkel, U. S. Oeol. Explor. Fortieth Parallel, VI., 107. ' F. M. Endlich, U S. Oeol. and Oeogr. Survey of the Territories, 1W73, 333. B. T. Putnam, Tenth Census, XV.. 472. ' Regis Chauvenet, "Notes on Iron Prospects in Northern Colorado,'' Biennial Rept. of the Colo. State School of Mines, 1886, 16. B. T. Putnam, Tenth Census, XV., 476. MAGNETITE AND P TRITE. 175 is in the Cebolla district, Gunnison County,' where the amount is reported to be large. The ores in basic hepheline rocks in BraziP are the only others in the Western Hemisphere. The Swedish and Norwegian ores are similar in their geological rela- tions to the several American types, viz. : those at Ekersund and SoggendahljHo the ores of Quebec and the Adirondacks; those at Routivara' to the aluminous ores of the Cortlandt series; the Taberg' ore is like that at Cumberland, R. I. ; and the Alno" occurrence resembles the Brazilian type. The titan- iferous iron sands will be referred to under magnetite sands. 2.03.13. Example 14. Cornwall, Pa. Deposits of soft magnetite, resting against igneous dikes and associated with green, pyritous shales, Siluro-Cambrian limestone and Trias- sic sandstone. These ore bodies are to be classed among the largest ever mined. They form three hills extending in an east and west direction, and called respectively Big Hill, Middle Hill and Grassy Hill. As the accompanying contour map shows. Big Hill is the highest and narrowest, while Middle Hill contains the most ore. The hills lie just at the southeast- ern edge of the Great Valley, and are six miles from the flour- ' Regis Chauvenet, "Iron Resources of GrunnisonCo.,"^mer. Rep. Col. State School of Mines, 1887, 18. "Iron Resources of Colorado," Trans. Amer. Inst. MinEng., XVIII., 273. Arthur Lakes, "The Great Cebolla River Deposits," Colliery Engineer, XVI., 367, 1896. ^ O. A. Derby, "Magnetite Ore Districts of Jacupiranga and Ipanema, Sao Paulo, Brazil," Amer. Jour. Sci., April, 1891, 311. ' T. Dahl, Forhandl. videnskabs Natm. i. Stockliolm, 1863. D. Forbes, Chem. News, December 11, 1868, 375. S. Forbes, Jour. Brit. Iron and SteelInst.,1874:,VSl. Th. Kjerulf, JV^/l Magazin for Natv.,XXVlI., 1S83. H. Rosenbusch, Idem. T. C. Thomassen, Idem. XXIV., 387. C. F. Kol- derup. Bergen's Museum's Aarbog. in Stockholm, 1896, 159. Rec. H. H. Reusch, Oeol. Foren in Stockholm, 1877, 197 ; Neues Jahrbuch. 1878. J. H. L. Vogt, Idem, XIII., 476, 683, XIV., 311; Geological Magazine, IX.. 83; Neues Jahrhuch , 1893, TI,, 69; Zeitschr. fur prakt. Oeologii, January, 1803, 6; October, 1894, 384; Archiv. fi'ir Mathem. og Natiirvidenskab, Kristiania, X. and XII., 1887. The papers of Kolderup and Vogt are of chief value for reference. * W. Petterson, Geol. Foren. i. Stockholm, XV., 45, 1893; (Neues Jahr- buch, 1894, I., 88) ; H. Sjogren, Idem. XV., 55, 140, 1893; (Neues Jahrbuch, 1894, I., 88). ' A. Sjogren, Geol. Foren. i. Stockholm, III., 42, 1876; (Neues Jahrbuch, 1876, 434). A. E. Tornebohm, Idem, V., 610; Neues Jahrbuch. 1883, II., 66. J. H. L. Vogt, Zeitschrift fur prakt. Geologic, January, 1893, 8. " A. G. Hoegboui, Geol. Foren. i. Stockholm, XVII., 100, 314, 1895. 176 KEMP'S OBE DEPOSITS. ishing little city of Lebanon. The geological section (Fig. 53) illustrates the position of the strata. The Siluro-Cambrian series is cut by an immense diabase dike near its southeastern limit, and on the south side of the dike which forms the north- ern rampart of the three hills lies the ore. The ore is a soft, rather earthy magnetite, which occasionally shows octahedra. While richer and purer on the original weathered surface, it is now interlaminated and closely involved with layers of limey shales which contain pyrite, at times in beautiful crystals. Most of the ore is merchantable raw, but large quantities are so low from this admixture of shales that they are being saved for possible future magnetic concentration. The presence of the pyrite makes it necessary to roast all the raw ore before I .^caZe of .Miles. Fig. 53. — Section along Cornwall Railroad from Lebanon to Miner's Village. After E. V. d'Inmlliers. Amer. Inst. Min. Eng., XIV., 898, 1886. smelting, but the phosphorus is so low that Bessemer pig is the chief resulting product. Big Hill differs from the others in structure. The northern dike with a steep southerly dip has an offsetting and very heavy branch to the southwest which forms with it a great trough or basin so far as one can see. The bottom of the ore has been reached by one rather shallow hole, but it seems quite certain that the dikes will come together at a point indicated by the several dips. The surface of the southerly branch is strongly corrugated. The ore of Middle Hill extends to a greater distance south from the dikes than that of Big Hill, and is cut by one small and unimportant offset of trap that is two or three feet across. At the western end of the workings, lime- 178 KEMP'S ORE DEPOSITS. stone is quite thick and in good exposure. It reaches well over to Grassy Hill. Grassy Hill is smaller, and is much less devel- oped than either of the others. E. V. d'Invilliers has empha- sized the important point that the dip of the ore in Big Hill is southwest at such an angle as to bring it below the Middle Hill bed, and that this latter also dips below the limestone and the Grassy Hill beds. Such being the case, enormous reserves must lie under the two western hills. The depths of the sev- eral bore holes given on the map and all in ore indicate its presence in very great amount, but it is important to show in this connection the absence of faults, for the map of Bailey Willis notes their presence, and observations of the writer cor- roborated their existence. The pyrite in the calcareous shales is occasionally replaced by chalcopyrite in irregular nodules or veinlets. The presence of copper was early noted, and some mining was done for it near the surface. Fine museum specimens of moss-copper, azurite, malachite, etc., were afforded. Even during the earlier iron- mining some copper ore was set aside as a small by-product. Copper is still present in the mine-water, for bright shovels left in it become coated, and the bones of dead animals thrown out on the ore banks, as well as chips of wood, etc., become tinted a bright green. Much difference of opinion has prevailed about the age and geological relations of these ores. Some have thought them Mesozoic and a part of the Triassic, while others, and notably J. P. Lesley, have regarded them as belonging to the Siluro- Cambrian series and analogous to the limonites of the Great Valley, but metamorphosed. The great trap dikes afford the most reasonable explanation or cause of the change, and to these may be referred the alteration. The apparent origin of many Siluro- Cambrian limonites from the hydration and oxidation of pyritous shales and schists gives much support to this view, and the association of limestone with the ore and the general stratigraphical relations are hard to explain in any other way.' ' E. V. d'Invilliers, "Cornwall Iron Ore Mines," Trans. Amer. Inst. 3Iin. Eng., XIV., 873. Rec. Lesley and d'Invilliers, Ann. Rep. Second Penn. Geol. Survey, 1885, 491. Rec. J. P. Lesley, Final Rep., I, 351, 1893. T. S. Hunt, "The Cornwall Mines," etc.. Trans. Amer. Inst. Min, Eng., TV., 319. H. D, Rogers, First Penn. Geol. Survey, II., 718. B. Willis, Tenth Census, XV., 233. MAGNETITE AND PYRITE. 179 The total production to April, 1894, is stated by Mr. Boyd, the superintendent of the mines, to be upward of 13,000,- 000 tons, while an annual output of 800,000 can be easily main- tained. The ore varies from 40 to b5% Fe. It almost never con- tains as much as 0.03 P, but runs up to 4% S. It is also sil- iceous. 2.03.13. Several other mines of somewhat related character to the Cornwall deposits are known along the edges of this Triassic belt, and associated with its trap intrusions. The mining districts lie near its north and south boundaries, and not far from its contacts with the older rocks. On the north side from east to west there are the Boyertown (Berks County), the Fritz Island and the Wheatfield, near Reading, and finally the Dillsburg in York County, west of the Susquehanna. On the south side in the same order are the French Creek, St. Mary's and the Jones, all quite near together and nearly south of Reading. Of these the Boyertown mines have been most worked.^ The Cornwall mines are between the Wheatfield and the Dillsburg. At the Boyertown mines the ore lies both between a brecciated limestone and Mesozoic sandstone and wholly within the limestone, but trap dikes are not lacking. At Fritz Island the ore is entirely enclosed in limestone, and is penetrated by a trap dike. In the Wheatfield mines the same brecciated limestone appears, and has the ore intimately asso- ciated with it. On both occurs the Mesozoic sandstone, and the succession is five times repeated by faulting. The usual trap penetrates the ore. The French Creek and St. Mary's mines are unique in that they are contained in gneiss. They are famous sources of fine crystals of pyrite, chalcopyrite and other minerals. The Jones mine exhibits the ore between trap and limestone, the trap being over the ore in the North pit aud ' P. Fraser, " Study of the Specular and Hematite Ores of Iron of the New Red Sandstone in York County, Pa.," Trans. Amer. Inst. Min. Eng., v., 132. Also Penn. Oeol. Survey, Rep CC, 205, 217. H. Hoefer, "Die Kohlen und Eisenerzlagerstatten Nord Amerika's," 241. Also Penn. Survey, Rev. C2. F. V. d'Invillier.s. "Cornwall Iron Ore Mines," Trauii. Amer. Inst. Min Eng., XTV.. 873. Rec. Lesley and d'Invilliers, Ann. Rep. Second Peiui. Survey, 1H8.5 J. P I e.sley. Final Report, "Vol. I., p. 351. 1892. Reo. T. S. Hunt "The Cornwall Mines," etc.. Trans. Amer. Inst. Min Eng., IV., 319 H. D. Rogers, First Penn. Oeol. Survey, II., 718. B. Willis, Tenth Census. Vol. XV., p. 223 Rec. 180 KEMP'S ORE DEPOSITS. under it in the south. A green shale is also rnet here, as in- deed in most of the other localities, although not specially men- tioned. At Dillsburg the evidence against the Triassic age of the ores is less positive, and upon this occurrence Fraser has based a strong argument for the latter view. Triassic sand- stone at times forms both walls, although there are instances where limestone appears as the foot. In all these localities the presence of copper is notable. It and the magnetic or metamor- phosed condition of the ore are probably referable to the trap. 2.03.14. Example 14a. Iron County, Utah. Beds of mag- netite and hematite bearing evidence of being metamorphosed limonite, in limestones of questionable Silurian age, and asso- ciated with eruptive rocks described as trachyte. The lime- stones have been much upturned, metamorphosed, and pierced by dikes and eruptive masses. The ore forms great projecting ridges and prominent outcrops, locally called "blow-outs." The usual lenticular shape is not lacking. They occur over an area of fifteen by five miles, and are in the southern end of the Wasatch Mountains. The samples show rich ores, which at times exceed the Bessemer limit of phosphorus. In the Star district the ore apparently lies between the quartzite and gran- ite. Hematite occurs in large amcunt, as does quartz, while some streaks have large crystals of apatite. The importance of the deposits lies in the future. They are the largest in the West, and are interesting in their bearing on the general origin of the magnetite. Coal, not proved to be good for smelting, is near, but centers of iron consumption are verj' far away.' 2.03.15. Example 15. Magnetite sands. Beds of magnetite sands concentrated on beaches or bars by waves and streams. The magnetite has been derived from the weathering of igne- ous and metamorphic rocks through which it is everywhere distributed. When in the sand of a sea beach, it and other heavy minerals tend to become concentrated by the sorting action of the waves. They resist the retreating undertow better than lighter materials. Such deposits are very abundant at ' W. p. Blake, "Iron Ore Deposits of Southern Utah." Trans. Amer. Inst. Min. Eng., XIV., 809. J. S, Newberry, "Genesis of Our Iron Ores," ■ School of Mines Quarterly, Mea'ch, 1880. Rec. Engineering and Mining Journal, April 23, 1881, p. 386; Prou. National Academy, 1880. B. T. Putnam, Tenth Ceitsns, Vol. XV., 486. Rec. MAGNETITE AND PYRITE. 181 Moisie, on the St. Lawrence, below Quebec, anci in the United States are known in smaller developments on Lake Champlain ; at Quogue, L. L; on Block Island; in Connecticut; along the Great Lakes, and on the Pacific coast. Grains of garnet, oli- vine, hornblende, etc., minerals of high specific gravity, are also in the sands. Many are too high in titanium to be of use, but there is no more difficulty in their concentration than in that of artificially crushed ore. In Brazil and New Zealand they have attracted attention.' 2.03.16. On the Origin of Magnetite Deposits. It is im- portant to note that magnetite deposits are almost always in metamorphic rocks, which owe their character to regional metamorphism or to the neighborhood of igneous rocks (Penn- sylvania and Utah). Gneisses form the commonest walls, but so-called norites, or gabbros, and crystalline limestones also contain them. Where there is lamination or foliation the mag- netite conforms to it. As the history of the metamorphic rocks is so often uncertain, the magnetites share the same doubt. In igneous rocks magnetite is the most widely occurring of the rock-making minerals. In all explanations the prevailing lenticular shape, ihe general arrangement in linear order, and the existence of great beds must be considered. The shape is very similar to that of deposits of specular hematite, with which magnetite is often associated. (Examples 9 and 10.) The following hypotheses have been advanced for the origin of magnetites: 1. Intruded (eruptive) masses. This supposes that the lenses have been intruded like a trap dike, and have then been squeezed and pinched apart. Though formerly much advocated, it is now generally rejected. 2. Excessively basic portions of igneous rocks. This supposes that large amounts of iron oxide have separated in the cooling and crystallizing of basic magmas. There are such occurrences, although seldom, if ever, pure enough or abundant enough for mining. The titaniferous magnetite of the Minnesota gabbros has been alluded to (2.03.26), and also the Brazilian ore and the Cum- ' T. S. Hunt, Oeol. Survey, Canada, 1866-69,, 261, 263; quoted in Six teenth Ann. Rep. Dir. U. S. Oeol. Survey, III., .50, 51; Can. Nat., VI,, 79. A A. Julien, "The Genesis of the Crystalline Iron Ores," ^4cad Nat. Sci., Phila., 1882, 335; Engineering and Mining Jonnwl. February 2, 1884. On New Zealand sands, E. M. Smith. Proc. Brit. Iron and Steel hist., May, 1896; Eng. and Min. Jour., June 13, 1896, p. 566. 183 KEMP'S ORE DEPOSITS. berland Hill (R. I.) peridotite. Should such igneous rocks be subjected to regional metamorphism and the stretching action characteristic of it, the ore masses might be drawn out into lenses. 3. Metamorphosed limonite beds. This idea has been most widely accepted in the past. It presupposes limonite beds formed as in Examples 1 and 2, which become buried and subjected to metamorphism, changing the ore to magnetite, and the walls to schists and gneisses. Igneous rocks have apparently changed limonites to magnetite at Cornwall, Pa., and in Utah, but such changes by regional metamor- phism are less easy to demonstrate. The limonite may have resulted from the oxidation of lenses of pyrite. 4. Replaced limestone beds, or siderite beds subsequently metamor- phosed. Such deposits may pass through a limonite stage. The general process is outlined under Example 9c, as devel- oped by Irving and Van Hise in the Gogebic district. The lenticular deposits of siderite at the Burden mines (Example 4) are very suggestive, and some such original mass might in instances be metamorphosed to magnetite. 5. Submarine chem- ical precipitates. This is outlined under Example 9d, as applied by the Winchells in Minnesota. 6. Beach sands. The lenses are regarded as having been formed as outlined under Exam- ple 15. The same heavy minerals sometimes occur with mag- netite lenses as are found on beaches." 7. River bars. This regards the lenses as due to the concentration of magnetite sands in rivers or flowing currents. Hence the overlapping lenses, the arrangement in ranges or on lines of drainage, and the occasional swirling curves found on the feathering edges of lenses, as in the Dickerson mine, Ferromont, N. J.' It is also reasonable to suppose that lakes or still bodies of water may have occurred along such rivers, and have occasioned the accumulation. 8. Segregated veins. By this method the iron oxide is conceived to concentrate from a state of dissemination in the walls by slow segregation in solution to form the ore horlies along favorable beds. The action is analogous to the formation of concretions, and is illustrated on a small scale by the well- ' See also Dakyns and Teall, Quar. Jour. Oeol. Soc, LXVIII., p. 118. '' See B. J. Harrington, Can. Geol. Survey, 1873, 193; A. A. Julien, Phila. Acad. Sci., 1882, 335. ' See H. S. Munroe, School of Mines Quarterly, Vol. III., p. 43 — an im- IDortant paper. MAGNETITE AND PYBITE. 183 known disks of pyrite, or of siderite, that form in clays and shales. It is a curious fact, however, that some magnetites are in wall rock that hardly shows a trace of a dark silicate. The lenses at Hammondville, in the Lake Champlain district, are in a white, or light-colored gneissoid rock, consisting of quartz, acidic plagioclase, and a few scattered garnets. In such surroundings segregation could not be applied, but where the walls are supplied with hornblende and other ferruginous minerals, and are reasonably basic, it might be advocated. Several other hypotheses with small claims to credibility could be cited. They are outlined at length in Bull. VI., Minn. Geol. Survey, p. 224, but in this place there has been no desire to take up any but those deserving serious attention. It may be said that while one or the other of the above seven hypotheses may in instances be applied with reason, yet most candid observers with widened experience have grown less positive in asserting them as axiomatic. ANALYSES OF MAGNETITES. (Oaution in interpi'eting analyses is again emphasized as under 2.01.26.) Fe. P. S. TiO,. SiO,. AI.O3. Canada (Rideau Canal) 50.23 49.24 66.00 62.10 63.00 48.82 53.75 42. 70 64.64 49.23 58.75 62.60 60.68 0.029 0.008 1.198 0.621 021 364 0.135 0.004 0.026 0.044 0.052 9.80 Chateaugay mines, N. Y., lump. . " " concentrated. 18.447 Mineville. N. Y. (Mine 21) Orange County, N. Y. (Forest of Dean) 0.148 0.080 Putnam County, N. Y ' 11.75 8 500 New Jersey (Hibernia) Cornwall, Pa 6.620 0.115 3.411 Cranberry, N. C Colorado (Calumet) . . ... 3.85 " flron Kine:) 0.123 0.120 Utali (Iron County) California (Gold Valley) 4.80 10.87 2.03.16. Of importance in connection with iron ore deposits are the recent studies of the distribution of phosphorus along certain lines in the beds, by a knowledge of which it is possi- ble to keep more valuable Bessemer ore distinct from less valuable. Such lines have been found in Michigan, and have been called by D. H. Browne "isochemic lines." Though less 184 KEMP'S OBE DEPOSITS. marked at the Burden mines (Example 3), the phosphorus was characteristic of certain varieties of the ore. Much work has also been done on the same question at Iron Mountain, Mo.^ PYRITE. 2.03.17. Example 16. Pyrite Beds. Beds (veins) of pyrite, often of lenticular shape and of character frequently analogous to magnetite deposits, in slates and schists of the Cambro- Silurian or Huronian systems, and less often in gneiss of the ^Archean. Slates are most common, and gneiss least so. They extend from Canada down the Appalachians to Alabama, being found at Capelton, Quebec ; Milan, W. H. ; Vershire, Vt. ; Charlemont, Mass.; Louisa County, Virginia; Ducktown, Tenn., and at many points less well-known in Alabama. Anthony's Nose, N. Y., the Gap mine, Pennsylvania, and Sudbury, Ontario, being different geological relations, will be mentioned under "Nickel" with other similar occurrences. 2.03.18. The ore bodies lie interfoliated in the slates or schists, and the different lenses often overlap and succeed each other in the footwall, and exhibit all the phenomena cited under magne- tites. Chalcopyrite is usually present in small amount, and where the copper reaches 3 to b% they are valuable as copper ores. (See under "Copper.") At present they are of increase ing importance as a source of sulphuric acid fumes for the manufacture of vitriol. Small amounts of lead and zinc sulphide are often present, and rarely a little silver. Nickel and cobalt occur, especially in the pyrrhotitic varieties. They are worthless as a source of iron. The smaller deposits of auriferous pyrites in the Southern States will be mentioned under "Gold." 2.03.19. Some pyrites lenses may have accumulated in a way analogous to the bog ore hypothesis, cited under "Magnetite"; but instead of the iron being precipitated as oxide, it has proba- bly come down as sulphide from the influence of decaying or- ganic matter, and has subsequently shared in the metamorphism and solidification of the wall rock. At the same time it must be ' D. H. Browne, " On the Distribution of Phosphorus at the Luddington Mines," etc., Trans. Amer. Inst. Min. Eng., XVII,, p. 616. I. Olmsted, "The Distribution of Phosphorus in the Hudson Elver Carbonates," Trans. Amer. Inst. Min. Eng., XVIII., p. 352, W. B. Potter, "Analysis of Missouri Ore," published in Mineral Resources, 1890, p. 47. MAGNETITE AND PYBITE. . 185 admittediio be an obscure point. By many they are thought, with more reason, to have originated like a bedded fissure vein whose overlapping lenticular cavities have been formed by the buckling of folded schists.' (Cf. "Gold Quartz," as later de^ scribed.) The Ducktown veins are on lines of dislocation be- yond question. Replacements of pinched beds of limestone are always to be considered, and the presence of intruded dikes, though disguised by metamorphism. is always to .be kept in mind. 3.03.20. The excavations in some of the mines in the pyi^te beds of Canada, just north of the Vermont line, have shown dikes of granite in close association with the ore. Thin sections of the granite indicate that it has suffered extremely severe dynamic metamorphism, for crushed and strained crystals make up nearly all of its substance. It is quite probable that the disturbance which causes the schistosity or slaty cleavage of the country rock likewise developed the strains in the granite which must thus have been intruded pre- vious to its operation. Before the shattering the dikes may have exerted a genetic influence in connection with the ore body, but now the ore is usually lean near them. The ore bodies are also cut by fine examples of the trap (camptonite) dikes which are abundant in the Lake Champlain Valloy. Prof. J, H. L. Vogt, of Christiania, Norway, has written of late regarding the origin of similar great bodies of sulphides in Europe, and when they occur in connection with rocks, ' W. H. Adams, "The Pyrites Deposits of Louisa County, Virginia," Trans. Amer. hist. Min. Eng., XII., p. ,527. O. R. Boyd, "The Utiliza- tion of the Iron and Copper Sulphides of Virginia, North Carolina, and Tennessee," Trans. Amer. Inst. Min. Eng., XIV., p. 81 ; Resources of 8. W. Virginia. H. Credner, "At St. Anthony's Nose, Hudson River," B. und H. Zeit., 1866, p. 17; " Pyrite in Virginia, Tennessee, and Georgia," B. und H. Zeit., 1871, p. 370. H. T. Davis, Mineral Resources of tlie U. S., 188.5, p. 501. William Martyn, Mineral Resources, 1883-84, p. 877. E. C. Mox- ham, "The Great Gossan Lead of Virginia" (altered pyrite in Carroll County), Trans. Amer. Inst. Min. Eng., XXL, p. 133. A. F. Wendt, "The Pyrites Deposits of the Alleghanies,' School of Mines Quar- terly, Vol., VII., and separate reprint; also Engineering and Mining Journal, June 5, 1886, p. 22, and elsewhere. Reo. H. A. Wheeler, "Copper Deposits of Vermont," School of Mines Quarterly, IV., 310. Arthur Winslow, "Pyrites Deposits of North Carolina," Ann. Rept. N. C Eifcperiment Station, 1886. 186 KEMP'S ORE DEPOSITS. which though now gneissoid, have been originally igneous, he regards them as basic segregations of an igneous magma. (See further 1.06.16.) Where they occur in schists he attributes their formation to ore-bearing solutions, penetrating along planes of weakness, and stimulated by neighboring igneous intrusions. In some of the instances cited the known igneous intrusions (as at Eammelsberg) are at some distance, and thus are not directly associated, so far as one can see, with the ore. The genetic connection is therefore somewhat hypothetical. 2.03.21. The relative importance of the different kinds of ore is shown by the following tables for 1880 and 1896. The increase in red hematite is due to the Lake Superior region, and to Alabama. In the immediate future the soft ores of the Mesabi district will help to greatly swell the total, but during 1893-94 there was great depression in the raining of iron ore throughout the country : 1880. Red hematite 3,512,713 . Magnetite .3,390,389 Brown hematite 2,149,417 Carbonate 922,288 Per cent. Per cent. of.rotal. 1896. of Total. 31.51 13,576,288 78.58. 39.98 1,311,526 7.57 36.95 2,136,312 13,38 11.56 91,423 0.57 7,974,806 100.00 16,005,449 100.00 As indicating the relative importance of the different mining regions, the following figures are of interest. No individual State producing less than 100,000 tons is given. states. Total in ISii. States. Toto!imI896 Michigan 5,706,736 Tennessee 535,484 Minnesota 4,283,880 New York 885,477 Alabama 3,041,793 New Jersey. 264,999 Virginia 859,466 Colorado 315,819 Pennsylvania 747,784 Georgia and N. Carolina 175,331 Wisconsin 607,405 All the others 181,375 Grand total 16,005,449 2.03.22. -Note. Large quantities of excellent Bessemer hematite are shipped to Baltimore and other Atlantic ports from the mines on the southeastern coast of Cuba, in the Jura- gua Hills. Santiago de Cuba is the largest town in this MAGNETITE AND P TRITE. 187 region, and is some twenty miles west of the mines. The coast range of hills consists mainly of syenite, according to J. P. Kimball, and the syenite is penetrated by many dikes and is mantled by sheets of diorite with which the ores are associated. Kimball refers the precipitation of much of the iron oxide which came from the diorite to coraline limestone, which had been accumulated as coral reefs on the syenite before the diorite was intruded, but he also mentions other deposits in the diorite not associated with limestone. From observations of another group of ores sixteen miles east of those studied by Kimball, F. F. Chisholm reached a different conclusion regard- ing their origin. Chisholm refers them to a source below and apparently regarded them as "veins or replacements of dikes. The amount of ore along this coast, both in place and as float is ver}' great,^ and will be an important feeder to American furnaces. Between three and four hundred thousand tons are now annually imported. Chisholm gives the following analyses : Fe. S. P. Juragua (Kimball) 64.65 .146 0.037 Sigua (Graham) 64.00- 0.040 0.016 Berraco (Chisholm) 60.00 0.027 0.027 Although not a source of supply for American furnaces, it is interesting to note in this connection that in Mexico vast depos- its of hematite and martite occur in Cretaceous limestone asso- ciated with intrusions of diorite. The paper of R. T. Hill cited below gives a review and full bibliography of the various localities. The notable deposits so far as yet opened up are at the Cerro de Mercado, in Durango,^ the Sierra de Mercado, ' J. P. Kimball, ' ' Geological Relations and Genesis of the Specular Iron Ores of Santiago de Cuba," Ainer. Jour. Sci., December, 1884, p. 416; also " The Iron Ore Range of the Santiago District of Cuba," Trans. Amer. Inst. Min. Eng., XIII., 613; Eng. and Min. Jour., December 20, 1884, p. 409. F. F. Chisholm, "Iron Ore Beds in the Province of Santiago, Cuba," Proc. Colo. Sci. Soc, III., 259, 1890. H. Wedding, "Die Eisenerze der Insel Cuba," Stahl und Eisen. 1892, No. 12. Prof. J. W. Spencer has beer recently working on the geology of Cuba and presented some of his results at the meeting of the American Association in Brooklyn, August, 1894. '' J. Birkinbine, "The Cerro de Mercado or Iron Mountain of Durango," Tratis. Amer. Inst. Min. Eng., XIII., 189, 1884. J. P. Carson, "Iron Manufacture in Mexico. ■ Idem, VI., 399. R. T. Hill, "The Occurrence of 188 KEMP-S ORE DEPOSITS. near Monclova in Ooahuila/ and others of minor importance in the States of Jalisco/ Guerrero'' and elsewhere. Several of these are now the basis of a small local smelting industry. Hematite and Martite Iron Ores in Mexico," ^?7ier. Jour. Sci., Februaxy, 1893, 111. B. Silliman, "Martite of the Cerro de Meroado, or Iron Moun- tain of Durango, and Certain Iron Ores of Sinaloa," Amer. Jour. Sci., November, 1882, 375. See also on the Durango Iron Mountain, Annales del Ministerio de Fomento de la Rep. Mexicana Tomo, III. , 1877 ; Eng. and Mill. Jour, on "Iron in Mexico, " November 10, 1888, p. 391. ' P. Frazer, " Certain Silver and Iron Mines in the States of Nueva Leon and Coahuila, Max.," Trans. Amer. Inst. Min. Eng., XII., 537. R. T. Hill, as cited in previous footnote. " J. P. Carson, as cited in second footnote. ' N. S. Manross, " Notes on Coal and Iron Ores in State of Guerrero, Mex., Amer. Jowr. Sci., May, 1865, p. 309; Remarks by J. D. Dana, p. 358. CHAPTER IV. COPPER. 2.04.01. Copper Ores. TABLE, or ANALYSES. Cu. S. Fe. 20.2 .... 34.9 30.50 25.8 11.70 <-S'i 26.7 1.39 '-1,(1 32.5 ss,, Native copper (generallywith some silver) 100.00 Chalcocite, Cu^S 79,80 Chalcopyrite. CuFeSj , 34.60 Bornite, CugFeSj •6fc79 Tetrahedrite, 4CuS2, Sb^Ss (variable) 26.50 Sb, . . 36,40 Enargite, CU3ASS4 (As, 19,1) 48.40 Cuprite, Cu.O 88. 8C Melaconite (tenorite), CuO 79,86 Malachite, SCuOCO^, HjO. 4O788 Azurite, SCuOCOj, H^O 4&r«- Chrysocolla, CuOSiOs, 'i'Rfi -S&rW- 3.04.02. Example 16, Continued. Pyrite or pyrrhotite beds (veins), with intermingled chalcopyrite. Whether the deposits are true beds or veins parallel with the foliation, is as yet a matter of dispute. The resemblance to magnetite sug- gests a bed, and this view is generally taken by German writers. The California mines occur closely associated with the auriferous (pyritous) quartz bodies, which are always esteemed veins. But as detailed knowledge increases, it is more and more appreciated that the ore bodies are mostly if not entirely veins and have been deposited along lines of dis- location.' Pyrites and pyrrhotite (called mundic by the miners) are the principal constituents of such bodies, but often the copper reaches 2.5 to 5%, and then they are valuable for copper. There " Compare in this connection .J H. L. Vogt, ' ' Ueber die Kieslagerstat ten von Typus Eoros Vigsnas, Sulitelma in Norwegen und Rammelsberg in Deutschland " Zeitschr. fur prakt. Geologic. February, April and May, 1894. 190 KEMP'S ORE DEPOSITS. is quite a characteristic group of minerals that is associated with the ores. Zinc blende is almost always present in small quantities, and is a great drawback to the ore when employed for acid. Galena is met in traces. Quartz, calcite, some form of amphibole, and often very beautiful garnets are associated. Ducktown is noted for its zoisite. All the secondary minerals of the oxidized zones of sulphides are met. The ores are often roasted for sulphurous fumes in acid works, and afterward the residues are shipped to the copper smelters. The mines have been or are being worked for copper near Sherbrooke, and at a great number of other points in Quebec, just north of Vermont. There are also not a few localities in Maine, New Brunswick, Nova Scotia and' Newfoundland, where operations of a more or less serious nature have been undertaken. Citations to the literature regarding these will be found at the close of the description of Ducktown. At Milan, N. H., there are several deposits in argillitic schists, and in the same region there are numerous other locations. At Vershire, Vt., there is a belt some twenty miles long, with three principal mining points. Of these the middle one, containing the Ely mine, is the .largest. Two beds of ore occur, separated by from 10 to 20 feet of schists. The lower averages about four feet, but fluc- tuates; the upper is still more variable, and may reach 25 feet. They are both formed by a succession of thin lenses. The ore is chalcopyrite, mingled with pyrrhotite and quartz. 2.04.03. More complete observations are available upon the Ducktown, Tenn., deposits, than upon any others of the tj'pe in America. The excellent paper by Carl Henrich is here spe- cially drawn upon and has been supplemented by some few fur- ther notes by the writer. Ducktown is situated in the south- eastern township of Tennessee, and occupies a small plateau between bounding ranges of higher mountains. The plateau has been much dissected by the present drainage, but its stumps remain, and serve to indicate the peneplain of Tertiary date.' The country rock is mica schist, with occasional heavier beds that tend toward quartzite or even gneiss. Some hornblendic rocks are present with the ores, but whether they represent in- truded dikes as suggested by Henrich, or streaks of siliceous ' C. W. Hayes. " GeomoriDhology of the Sontliftrn Appalachians," Na- tional Geographic Magazine, VI. , 68, 1894, -Eig. 2. MAP O.F THE DUCKTOWN MINES. FlQ, 55. — Map of the mines and of the outcrop of gossan, showing the relations and extent of the veins at Durktown . Tenn. Aftrr Curl Henrich, Trans. Amer. Inst. Jfin. ling., XXV., 178, 1895. 193 KEMP'S ORE DEPOSITS. limestone, it is not possible to determine. The schists are metamorphosed shales, and the schistositj' appears to be gener- ally parallel to the original bedding. The geological age is still in dispute, but is probably Pre-Cambrian. The .schists strike N. 20-25 E., and have a prevailing dip of about 50 to 55 S. E. There are variations of the latter which are due to rolls and faults. The schists have been broken by dislocations along which the ores have been deposited. The strike of the ore is parallel to the strike of the schists, and the dip is, as a rule, the same as that of the schists, but cases have been observed where the ores cut the dip of the country rock, al- though with such soft and easily mashed materials it is diffi- cult to identify the unconformity. There are two principal belts of fracture as shown by the map. Fig. 55, and probably several minor ones, between. The Old Tennessee, Burra Burra, London and East Tennessee lie along the northwest belt; the Polk County, Mary, and Calloway form the southeast belt ; and the Culchote and Isabella lie in the interval. The ore bodies are huge lenticular masses of sulphides, which probably owe this shape, as far as it is at all discernible, to diagonal faulting since the veins were filled. The common ore is an aggregate of pyrrhotite, chalcopyrita, calcite, quartz, zoisite, and in some mines much actinolite. Zinc blende and galena are present, but are insignificant. Garnets are occasionally met in quantity. On some of the claims pyrites is abundant, as in the Burra Burra, and, as is reported to be the case at the Isa- bella, it taking the place of the pyrrhotite to a greater or less degree. The content of copper varies up to 3.5%, with occasional bunches that run higher. The old black copper ores that accumulated at the water-level are now exhausted. (See Fig. 56.) From observations on the succession and character of the minerals in the vein, J. F. Kemp has drawn the following conclusions regarding the geological history of the veins. By a process of regional metamorphism, a sedimentarj' series of shales and sandstones was altered to mica schists and quartz schists. Where the ore is now found, zoisite, tremolite, and garnet were also produced, but it is not known whether they are met outside of the mines or not. They indicate the former presence of magnesian and calcareous rocks, althougn, gener- ally speaking, lime is practically unknown in the metamorphic COPPER. 193 rocks of the district and the local waters are remarkably pure and soft. Whether a calcareous shale or an intruded dike yielded the lime silicates, or whether they are met&morphosed, calcareous, vein material from an older vein filling cannot be stated. After the general metamorphism, a series of disloca- tions was developed along the lines of the present veins, and Cross-Section A-a. (Fig. 8.) Shaft 3. Old Tennessee Mine. 5 10 Fig. 56. — Cross-section, Shaft Z, Old Tennessee Mine, Ducktown, Tenn., show- ing the gossan, the black ore, the pyrrhotite and a fault. After Carl Hennch, Trans. Amer. Inst. Min. Kng., A'A'T'., 198, 1895. pyrrhotite and sometimes pyrite were introduced. After the deposition of the pyrrhotite there was further movement which shattered the pyrrhotite and allowed the introduction of ^hal- copyrite in streaks and fine veinlets all through it. Still later, and apparently after another movement calcite came in and 194 KEMP'S ORE DEPOSITS. penetrated the shattered sulphides and older silicates. After the introduction of the calcite, by some movement fissures notably horizontal were produced, which became filled with glassy quartz, and which have yielded the so-called "floors." More or less contemporaneously with the quartz, coarsely crystalline pyrrhotite, chalcopyrite and blende were produced, which are in marked contrast with the earlier sulphides. The oxidation of the veins above the ground water, the formation of the brown hematite outcrops and the development of the zone of enrichment (the black ores) bring the process down to the present.' 3.04.03. Throughout the mountainous region of western North Carolina, eastern Tennessee and northern Alabama are many other copper deposits of more or less serious importance. One of the best known is the one formerly operated at Ore Knob. This is described by Kerr as a true fissure vein, extending 2,000 feet on the strike, which is parallel to that of the gneiss, but cutting the dip in descent. The width averaged about 10 feet. The gossan extended to a depth of 50 feet, and furnished the usual body of rich ore at the contact with the sulphides. The mine has not been operated for some years.^ ' Trans. Ainsr. Inst. Min. Eng., 1899. ° For a general account of the sulphides in the East, see A. Wendt, "The Pyrites Deposits of the AUeghanies," School of Mines Q^iarterly, VII., 1886. Canada, Oeol. Survey of Canada, 1863, 709. James Richardson, Idem,, 1896, 34-44. E. W. Ells, "Copper in Quebec," Idem, 1890, Vol. IV., 29K. Rec. "The Mining Industries of Eastern Quebec," Trans. Amer. Inst. Min. Eng., XVIII. , 316, 1889. John Blue, "Copper Pyrites Min- ing in Quebec in l%Qi," Journal Oen'l Mining Assoc. Piov. Quebec, II., 147, 1891. S. L. Spoflford, " Albert Mines and Capelton Chemical Works, " Idem, 214. C. T. Jackson, "The Great Copper-bearing Belt of Canada," Proc. Bast. Soc. Nat. Hist., IX., 302, 1862. Copper prospects have received attention in southwestern New Brunswick, on Adams, Campobello, and other islands. See Bailey and Matthew, Geol. of Canada, 1870-71, p. 13. " On Notre Dame Bay, Newfoundland, " M. E Wadsworth, Amer. Jonr. Sci.,iii., XXVIII., 28, 103. Maine. — "Blue Hill District", Eng. and Min. Jour., August 38, 1880, p. 140. F. L. Bartlett, "Mines of Maine," in Mines, Miners and Mining Interests of the United States, Philadelphia, 1883, 133. J. D. Whitney, Metallic Wealth of the United States, 312. New Hampshire.— C. H. Hitchcock, Geol. of N. H., III., Part III,, p. 47. Vermont. — "Elizabeth Copper Mines," Eng. and Min. Jour., November 'n u» ^ T-) ^ Si ^ Eh V. S aj ■^ hO ■*- «• Os o ^ 1= W, s fc^ sf ~r ^ ^ l«l o r<; .^• (5 s ^ cc £~ ^^ ? S 5s CO * ^ - •g HO- r 1 1^ 1^ t J* ^ (a M- -8 ^ o S" ft ^ e !. ss a V Chert seams Sulphuret ore ^— Floor 2nd. Magnesian Limest&na Fig. 67. — Cross section m the St. Genevieve copper mine, illustrating the rela- tions of the ore. After 7^. Nicholson, Trans. Amer. Inst. Min. Eng., X., 450. sippi, about forty miles south of St. Louis. The Second Magne- sian Limestone of the Cambrian outcrops, with the Carbonif- erous on the north, and more or less Quaternary in the vicin- Limestone (I " 1|8 I X A I' 1>8 Fig. 68. — Section at the St. Oencvieve mine, illustrating the intimate relations of ore and chert. After F. Niehnlson, Tranx. Amer. Inst. Min,. Eng , X, 451. ity. There are two nearly horizontal beds of ore, of widths varying between three inches and several feet. They lie be- Whitney, J. D., "On the Black Oxide of Copper of Lake Superior," Proc. Boston Soc. Nat. Hist., January, 1849, p. 103; Amer. Jour. Sci. ii., VIII., 273. Metallic Wealth of the United States, p. 345. Rec. Whittlesley, C, "On Electrical Deposition," Amer. A.ssoc. Adv. Sci., XXIV., 60. Wright, C. E., and Lawson, C. D., Mineral Statistics of Michigan. An- nual formerlv issued. ai4 KEMP'S ORE DEPOSITS. tween chert seame, and are associated with ciay and sand. The ore is thought by Nicholson to have been deposited in cavi- ties formed by dolomitization, much as is advocated by Schmidt for the lead and zinc deposits of southwest Missouri, and as is described under Example 25. For ten years the mines have not been operated.' Fia. 69, — Geologieal map oftlie Morenci or Clifton copper district of Arizona. After A. F. Wendt, Trans. Amer. Inst. Min. Eng., XV 33. 2.04.18. Example 20. Arizona Copper. Bodies of OJn dized copper ores in Carboniferous limestones, associated with eruptive rocks. In addition to these, which are the most important, there are veins in eruptive rocks, or in sandstones, or ore bodies of still different character as set forth under the several sub-examples. The copper districts are nearly all in ' F. Nicholson, "Review of the St. Genevieve Copper District," Trans Amer. Inst. Min. Eng., X., 444. B. F: Shumard, "Observations on the Geology of the Covinty of St. Genevieve, Missouri," Trans. St. Louis Acad. Sci., I., 40; abstract in 4?;ier. Jour. Sci., ii., XXVIII., 136. COPPER. 215 the southeastern part of the territory, but the Black range is near the center. LONGFELLOW ,v"'HIUL Fig. Id. — Vertical section of Longfellow Hill, Clifton district, Arizona. After A. A'. Wendt, Trans. Amer. Inst. Min. Eng., XV., 52. \ \ \ K V N \ \ w Fia 71. — Horizontal sections of Longfellow ore body. After A. F. Wendt, Trans. Amer. Inst. Min. Eng., XV., 53. 2.04.19. Example 20a. Morenci. The Morenci district, known also as the Clifton or Copper Mountain, lies in a basin, 216 KEMP'S ORE DEPOSITS. six to ten miles across, whose high surrounding hills consist of limestone, probably Lower Carboniferous, which rests on sandstone, and this on granite. The principal mines are grouped about the town of Morenci. Clifton is seven miles distant at the point where the smelter of the Arizona Copper Company is located. In the basin is a mass of porphyry, con • taining frequent great inclusions of limestone. Felsite or por- phyry dikes are also abundant in the surrounding sedimentary and granite rocks. Several miles to the east there is an out- flow of late trachyte and evidence of recent volcanic action. From this it appears that eruptive phenomena are abundant ind widespread. .PORPHYRY '++■' Fig. 73. — Geological section of the Metcalf mine, Clifton district, Arizona. After A. F. Wendt, Trans. Amer. Inst. Min. Eng., XV., 36. 2.04.20. The ores are classified by Henrich as follows: 1. Contact deposits. These occur in a zone of decomposed and kaolinized porphyry, between a bluish, fine-grained lime- stone, and solid porphyry. Many ore bodies, and probably the largest, are directly on the limestone, while others are sur- rounded by the decomposed porphyry. As included masses of limestone, with associated ore, are found in the decomposed porphyry, it is probable that these ore bodies may have origi- nally replaced such. The ores are malachite, azurite, cuprite, with some metallic copper and melaconite, in a gangue princi- COPPER. 317 pally of limonite. Wad is also frequent. Much clay of a residual character occurs with the ores. 3. Deposits in limestone. These are closely associated with the first class, and have apparently formed as outlying bodies in the limestone, as they are connected by ore channels with the principal lines of circulation along the contact. They ap- pear to contain more wad and lime than the typical contact deposits. 3. Deposits in porphyry. These form sheets and pockets in porphyry, or impregnate the solid rock itself. They are oxi- dized at the surface, but pass in depth into chalcocite. The principal gangue is kaolinized porphyry. The impregnated porphyries are to-day the chief ore supply. According to Wendt the Coronado vein fills a longitudinal fissure in a quartz porphyry dike. It afforded chalcocite above, .but passed into chalcopyrlte beloM'. Wendt also mentions a group of veins in granite that likewise afforded chalcocite.^ 3.04.21. Example 30fe. The Bisbee district, called also the Warren district, is situated in the Mule Pass Mountains in southern Arizona, near the Mexican line. The range runs east and west, and consists of beds of Lower Carboniferous lime- stone, dipping away from a central mass of porphyritic rock. The ores are found in the caiions on the south side, which have been formed by erosion, along the contact of the limestone and porphyry. They are of the same oxidized character as at Mor^nci, and in the important mines occur in limestone. James Douglass describes them as being situated at a distance from the porphyry of perhaps a thousand feet or more, and as forming in their unaltered state huge masses of pyrites with copper often as low as two per cent. They have been pro- duced, as nearly as one can judge by replacement of the lime- stone, through the agency of solutions, which brought much siliceous and aluminous matter as well. It is natural to look to the porphyry as the source of the latter material. The sul- ' J. Douglass, "Copper Resources of the United States," Trans. Aiiier. Inst. Min. Eng., XIX. 678, 1890. Rec. "Arizona Copper and Copper Mines," Eng. and Min. Jour., August 13, 1881, p. 103. "Clifton Copper Mines of Arizona," 76id., February 31, 1880, p. 133. C. Henrich, "The Copper Ore Deposits near Morenci. Ariz.," Ihid.. March 26, 1887, pp. 208, 219. Reo. A. Wendt, "Copper Ores of the Southwest," Trans. Amer. Inst. Min. Eng., XV., p. 33. Rec. 218 , KEMP'S ORE DEPOSITS. phides pass in alteration into bodies of oxidized ore, which re- main in the midst of ferruginous clay, called "ledge matter" by Dr. Douglass. Thoroughly oxidized masses, as well as oth- ers whose outer shell is alone changed, are known. One mass in the Czar shaft of the latter character is estimated at 1,000,- 000 tons of ore. The degree of alteration does not appear to be dependent on the vertical position, as bodies of sulphides are known to be higher up than thoroughly oxidized masses, but in this arid region the ground-water stands at a very consider- able depth, and appears not to have been yet actually reached, although much trouble is caused by floods during periods of rain. Above the bodies of ore empty caves are usually found, and so frequent is this association that when the prospecting drifts strike a cave the miners immediately sink in the expec- tation of striking an ore body in depth. Sink-holes on the sur- face have been successfully used as guides in the same way. In the accompanying picture of the mine. Fig. 7.3, the lime- stones dip into the hill, away from the shaft, and the ores are found in them, and beneath the valley below. The rock referred to as porphyry above has been microscopi- cally determined by A. A. Julien for Arthur Wendt to be a quartz-porphyry with a felsitic ground mass (felsite-porphj'ry of Julien). Its contact with the limestones is marked by a zone of kaolinization, or alteration, and is not sharp. Positive evi- dence of contact metamorphism has not yet been recorded, but the effects of circulating waters are pronounced. The results of detailed geological study of the region will be awaited with interest.^ 2.04.32. Example 20c. Globe District. As in the other districts the most productive mines are in limestone near the contact with eruptive rocks. 1. Contact deposits in limestone. At the Globe mines the Carboniferous limestone abuts against a great dike of diorite, while trachyte and granite are near. Along the contact there is abundant evidence of thermal action in the kaolinized rock. ' J. Douglass, "Copper Resources of the United States," Trans. Amer. Inst. Min. Eng., XIX., 678, 1890. Rec. "The Copper Queen Mine," New York meeting of the Amer. Inst. Min. Eng., Febmary, 1899. See Eng. and Min. Jour., February 35, 1899, p. 330. A. Wendt, "Copper Ores of the Southwest," Trans. Amer. Inst. Min. Eng., XV., p. 53. Rec. % ,L% J" %v ii- ; o s c oq 3. I I CO I— I COPPER. 3 J 9 The great bodies of oxidized ores are found on this contact and extend out into the limestone. The one on the Globe claim is described by Wendt as resembling a great chimney. 2. A fissure vein in sandstone, containing arsenical and antimonial copper ores, and known as the Old Dominion, was formerly worked. 3. Fissure veins in talcose slate and gneiss, and filled by a quartz gangue with bunches of malachite and azurite (New York and Chicago mines), and now no longer worked. 4. Numerous small veinlets forming a stockwork, in gneiss near a dike of diorite, which is crossed by a dike of trachyte. These are known as the Black Copper Group. The ores are too low grade for profitable exploitation. Of greater interest are the bodies of chrysocolla, found in the wash down the hill from the outcrop of the veins, and evidently due to the super- ficial drainage of the stockworks. Similar bodies of ore, though not chrysocolla, were found at Rio Tinto, in Spain.' 2.04.23. Example 20d. Santa Rita District. Although in New Mexico, this district has much in common with those already mentioned. A great dike of felsite cuts limestones, and along the contact, as well as in the felsite itself, copper ores are found. 1. Contact deposits in limestone. These afforded the usual oxidized ores, but were not found to extend to any great depth, and while for a time productive, they were soon exhausted. 2. Deposits in felsite. These consisted of pellets and sheets of native copper in the dike itself, which were oxidized to cuprite near the surface. (Cf. Lake Superior amygdaloids, Example 18.) They were worked by the Mexicans in the early part of the present century.^ ' J, Douglass, " Copper Resources of the United States," Trans. Amer Inst. Min. Eng., XIX. 678, 1890. Rec. "The Globe District," Eng. and Min. Jour:, April 9, 1881, p. 343. W. E. Newberry, "Notes on the Pro- duction of Copper in Arizona," School of Mines Quarterly, VI., 370. A. Trippel, "Occurrence of Gold and Silver in Oxidized Copper Ores in Arizona," Eng. and Min. Jour., June 16, 1883, p. 435. A. Wendt, "Cop- per Ores of the Southwest, " Trans. Amer. Inst. Min. Eng., XV., p. 60. ^ A. F. Wendt, "Copper Ores of the Southwest," Trans. Amer. Inst. Min. Eng., XV., 37. Wislizenus, "On the Santa Rita Mines: Memoir of a Tour in Northern Mexico, 1846-47," p. 47; Amer. Jour. Sci., ii., VI., 385, 1848 320 KEMP'S ORE DEPOSITS. 3.04.24. Example 20e. Black Range District. This is now the leading copper producer of Arizona, and has come into great prominence within a few years. In its geological rela- tions it appears to be more like the California deposits than any others, but there are as yet but few recorded details. It appears that there is a great dike of more or less porphyritic, dark green rock that has been extensively fractured along a broad line of dislocation for several miles. The fractured zone strikes north 10° west, and outcrops about 5,800 feet above tide. The writer has examined thin sections of the dike- rock, which is locally called diorite, but the specimens at hand were too thoroughly decomposed to admit of close identifica- tion. No dark silicates were visible, and chloritic products aloue indicated their former presence. Broadly rectangular feldspars were the chief minerals, but they were too badly altered, even to indicate their character, although no positive, polysynthetic twinning could be detected. Quartz was com- mon. In depth sheared dike rock is met that resembles sla^^e. The ore, which embraces both bornite and chalcopyrite, fills the cracks and larger fissures and impregnates the slaty rock. There is some galena present, and earthy lead sulphate has resulted from it in the gossan. The ore carries both gold and silver, The inaccessible situation of the mines long hindered their development, but now, with a mountain railway to give them an outlet, they are very productive. They are operated by the United Verde Companj', and are about 20 miles west of Prescott. ' 3.04.35. Example 20/. Copper Basin. Beds of closely tex- tured conglomerate and sandstone, resting on granite and gneiss, and having a cement of copper carbonates. Copper Basin lies about twenty miles southwest of Prescott, and is formed by a depression in greatlj' decomposed granite, which is traversed by numerous small veinlets of copper ores. The granite is pierced by porphyry dikes, and covered by the sedi • ' J. F. Blandy, "The Mining Region Around Prescott, Ariz.," Travs. Amer. Inst. Min. Eng., XI., 286. G. K. Gilbert, "On the General Geology of the Black Mountain District," Wheeler's Survey, III., p. 35. A. R. Marvine, "Brief Betails of the Verde Valley," Wheeler's Survey, III., p. 209. A. F. Wendt, " Copper Ores of the Southwest," Trans. Amer. Inst Mill. Evg., XV., 63. Rec. J COPPER. 231 mentary conglomerates and sandstones into which its copper is thought by Blake to have partially leached and precipitated as a cement. Reference, by way of comparison, may be made to the Lake Superior conglomerates, in which, in part, the native copper serves as a cement.': 2.04.26. There are numerous other copper districts in Ari- zona of minor importance, or entirely undeveloped, but the ex- amples above cited probably illustrate the occurrences quite fully. Those not referred to are of sporadic development. Copper prospects are known in the Grand Canon of the Colo- rado, and have received some attention.^ Mention should also be made of ithe mines in Lower California, opposite Guayraas, a brief description of which will be found in Wendt's paper.' The copper ores impregnate beds of submarine volcanic tuff, and are unique in their geological relations. Much copper is now met in depth at Leadville, Colo. The geology of the mines is set forth under Lead-Silver. 2.04.27. Example 309'. Crismon-Mammoth, Utah. In the Tintic district, Juab County, are three great ore belts, in ver- ticallj" dipping dolomitic limestone, as more fully set forth under "Silver" (Example 35a). One of these, the Crismon- Mammoth, contains ores that bear silver, gold, and copper in proportions of about equal value. They have been a very difiS- ' cult mixture to treat successfully. Of late considerable copper has been produced, placing the ore deposits among those deserv- ing mention. The ' Crismon-Mammoth vein or belt covers a maximum width of 70 feet, and runs 500 feet on the strike, dipping 75° west. The ores seems to have been deposited along the bedding planes, though often cutting across them. The pro- ductive portions are found in richer chutes or chimneys, amid much low-grade material and gangue, and are of all shapes and sizes, from 25 feet in diameter, down. The Copperopolis ' W. P. Blake, "The Copper Deposits of Copper Basin, Arizona, and their Origin," Trans. Amer. Iiisf Mm. Eng., XVII., 479. ' J. F. Blandj', "Oil Arizona Copper Deposits," Eng. and Min. Jour., 1897, V^ol, LXIV.,p, 97. ° See also M. E. Saladin, "Note sur les Mines de Cuivre du Boleo CBasse Calif ornie)," Bull, de la Societe de I' Industrie Minerale, 3 Serie, VI., 5, 283. 232 KEMP'S OBE DEPOSITS. is thought to be on the same belt, and is a neighboring location of similar geological structure and ores.' A very important body of chalcocite was discovered in 1898 in Bingham Canon, whose geological relations are similar to those described for the lead-silver ores under 2.08.33. Its loca- tion was on the Highland Boy claim. 3.04.38. Wyoming, Idaho, Washington. Oxidized ores have been exploited to some extent at the Sunrise mines, in the Laramie Range, Wyoming. Iron ores are in the same region (see under Hematite). Other copper prospects have been opened in the Wood River region in -northern Wyoming, and at other points, but the geological relations have not yet been described. 2.04.29. In the extreme western border of Idaho, near the Oregon line, the Seven Devils district has been located and developed to a considerable degree. Intrusions of diorite have pierced a white marble and upon the contacts and upon in- clusions have developed extensive aggregates of garnet, epidote and specular hematite, together with very considerable amounts of bornite. Green prophj'ritic dikes are also present. Lind- gren regards the ore as formed by pneumatolytic processes set up by the diorite. As also remarked by Lindgren the type of ore body is known in Mexico, and indeed a number of cases have come to the notice of the writer.^ Not a few copper prospects have been located in Washington, but they are as yet of somewhat undemonstrated value. North of Lake Chelan in the Stehekin district copper sulphides, pyrites and mispickel impregnate brecciated, andesitic dikes in marble.' A vein in King County* is described as occurring in syenite. 2.04.30. Example 31. Copper ores in Triassic or Permian sandstone. They occur as oxidized ores, with native silver, ' O. J. HoUister, "Gold and Silver Mining in Utah," Travis. Amer. Inst Min. Eng., XVI., p. 10. D. B. Huntley, Tenth Census, Vol. XIII., p. 456. A report on the Tintic District is in press with the U. S. Geol. Survey, but is not available at this writing. ' E. L. Packard, "On an Occurrence of Copper in Western Idaho," Amer. Jour. Sci., October, 1895, 398. W. Lindgren, "Copper Deposits of the Seven- Devils,'' Mining and Scientific Press, Feb. 4, 1899, 135. Rec. " As leai-ned from the wi-iter'a friend, Charles Of, froni whom material has been obtained and examined. ■' R. H. Norton, "A Washington Copper Deposit," Eng. and Min. Jour., February 11, 1899, 173. COPPER. 223 and chalcocite in contact deposits in Triassic and Permian sandstones at their junction with diabase or gneiss, or as dis- seminated masses replacing organic remains. Copper ores are very common throughout the estuary Triassic rocks of the Atlantic coast, and although formerly much mined, they are now proved valueless, and of scientific interest only. 2.04.31. Example 21a. Contact deposits in sandstone at its junction with diabase. These include the New Jersey ores, vigorously worked before the Revolution. They consist of the carbonates, of cuprite and of native copper, disseminated through saiidstone near the trap. The Schuyler mines, near Arlington, N. J., and several other openings near New Brunswick, N. J., are best known. These Triassic diabases often show chalcopy- FlG. 74. — Gross section of the Schuyler (lopper mine. New Jersey, a, trap; b, sandstone; c, shales; the black .shading, copper ores. After N. H. Darton, U. S. Geol. Survey, Bull. 67, p. 57. rite, and it is probable that the copper came from this or from copper in the augite of the rock, in accordance with Sand- berger's investigations. The deposits are unreliable, and ex- cept at a very early period have never been an important source of ore. 3.04.32. Example 216. Contact deposits in sandstones at the junction with gneiss. A number of deposits were formerly worked of this character, especially at Bristol, Conn., and at the Perkiomen mine, Pennsylvania. The mine at Bristol, Conn., is a well-marked contact deposit, on the line between the Triassic sandstone and the schistose rocks. The contact runs northeast and southwest, has suffered great decomposi- 224 KEMPS OUE DEPOSITS. tion from mineral solutions, and has been largely kaolinized. A broad band of this decomposed material, 30 to 120 feet wide, lies next the sandstone, and contains disseminated ore. Then follow micaceous and hornblende slates, often with horses of gneiss. The slates are much broken by movements that have formed cavities for the ores. It is reasonable to connect the stimulation of the ore currents with the neighboring trap out- breaks. Unusually fine crystals of chalcocite and barite have made the mine famous the world oyer. While at one time a source of copper, for many years it has been unproductive.' 2.04.33. Example 21c. Chalcocite and copper carbonates replacing vegetable remains, etc., in the Permian or Triassic sandstones of Texas, New Mexico, and Utah. In the Permian of northern central Texas are three separate copper-bearing zones, forming three lines of outcrop that extend in a general northeasterly direction over a range of about three counties. The ore is largely chalcocite in beds of shale, and often re- places fragments of wood. It may be available in time.^ At various places in Utah and New Mexico (Abiquiu, N. M., Silver Reef, Utah), the sandstones, as reported by Newberry and others, have copper ores disseminated through them and deposited on fossils, at times with associated silver (Utah). The copper, whether coming from the waters along the shore line or from subterranean currents, was precipitated by the organic matter. (See also under "Silver," in Utah.) These deposits are not yet sources of copper.' ' L. C. Beck, "Notice of the Native Copper Ores, Copper, etc., near New Brunswick, N. J.," Amer. Jour. Sci., i., XXXVI., 107. G. H. Cook, Geol. of N. J.. 1868, p. 675; also L. C. Beck, Ibid., 218-224. J. G. Perci- val. Rep. on Geol. of Conn., p. 77. 0. A. Shaefifer, " Native Silver in New Jersey Copper Ore," Eng. and Min. Jour., February, 1882, p. 90. C. U. Shepard, Oeol. of Conn., 1837, p. 47. B. Silliman and J. D. Whitney, ' ■ Notice of the Geological Position and Character of the Copper Mine at Bristol, Conn.," Amer. Jour. Sci., ii., XX., 361. J. D. Whitney, Metallic Wealth. Rec. ^ W. F. Cummins, "Report on the Permian of Texas and its Overlying Beds,' First Ann. Rep. Texas Geol. Survey, p. 196. J. F. Furman, " Geology of the Copper Region of Northern Texas and Indian Territory," Trans. N. Y. Acad. Sci., 1881-83, p. 15. ^ F. M. F. Cazin, " The Origin of the Copper and Silver Ores in Triassic Sand Rock," Eng. and Mi)i. Jour., April 30, 1880; December 11, 1880, 331. "The Nacemiento Copper Deposits," iWd., August 22, 1885, p. 124. A. COPPER. 235 2.04.3,4. Copper production in 1882, 1890 and 1897, in tons of 2,000 pounds each: 188a. 1890. 1897. Lake Superior 28,578 50,372 72,920 Montana 4,539 56,490 118,579 Arizona 8,993 17,398 40,510 Colorado 747 441 4,719 New Mexico , 434 435 California 413 11 7,065 Utah '. 303 503 1,937 Elsewhere 1,413 3.906 2,874 Copper sulphate 6,501 45,408 139,546 355,095 The figures indicate in general a vast increase in production, and, above all, the advance of Montana. For detailed statis- tics The Mineral Industry, issued annually by the Scientitic Publishing Company, New York, and the Annual Eeports of the Director of the U. S. Geological Survey are the chief books of reference. W. Jackson, Rep. Director of the Mint. 1880, p. 334. J. S. Newberry, "Copper in Utah, Triassic Sandstones," Eng. and 2Iiii. Jour., Vol. XXXI., p. .5. Also October 33, 1880, p. 369; January 1, 1881, p. 4. See also Tcntlt Census, Vol. XIII., Precious Metals, pp. 40, 478. C. M. Rolker, "The Sil- ver Sandstone District of Utah," Trans. Amer. Inst. Min. Eng., IX., 31. R. P. Rothwell, quoted in Tenth Census, Vol. XIII., p. 478. B. Silliman, "The Mineral Regions of Southern New Mexico," Trans. Amer. Inst. Min. Eng., XVI., 437. CHAPTER V. LEAD ALONE. 2.06.01. The deposits of lead aie treated in three different classes, according as they produce or have produced lead alone, lead and zinc, or lead and silver. Of late years the lead-silver ores have been the great source of the metal. Only the southeast Missouri region is of much importance among the others, although considerable lead is also obtained in associa- tion with zinc. LEAD SERIES. Pb. S Galena, PbS 86.6 13 Cerussite, PbCO, 77.5 Anglesite, PbSOj..., 68.3 Pyromorphite, PbsPsOs+l/SPbClj. 76.86 Earthy mixtures of these last three and limonite. 2.05.03. Example 22. Atlantic border. Veins of galena in the Archean rocks of the States along the Atlantic border ; also others in Paleozoic strata, as described in the sub- examples. 2.05.03. Example 22a. Veins in gneiss and crystalline lime- stone, sometimes with a bariteor calcite gangue. These depos- its were vigorously exploited forty years ago or more, but have since been of small importance other than scientific. They may be described best by districts, as they hardly deserve a greater prominence. 2.05.04. (1) St. Lawrence County, New York. Veins with galena in a gangue of calcite in Archean gneiss. Those near Rossie are perhaps best known, especially for their tmusually interesting calcite crystals. There are numbers of veins in the district which are notable in that the galena is without zinc or iron associates. The lead carries a very small amount of silver, LEAD ALONE. 327 not enough to separate. Hornblende and mica schists occur in the same region, and the Potsdam sandstone is not far removed. A few minor veins cut the Trenton limeatone near Lowville, Lewis County, sometimes with fluorite for a gangue.' 2.05.05. (2) Massachusetts, Connecticut and eastern New York Veins of galena with more or less chalcopyrite and pyrite in a quartz gangue in gneiss, slates, limestones or mica schists. The mines ne,ar Northampton, Mass., were formerly well known, although never productive of a great deal of metal ; hut as there is a large, prominent vein, it attracted attention. There are numerous others in the same region. Veins also occur at Middletown, Conn., where much silver is said to be found in the galena. More recently {circa 1873) at Newburyport, Mass., argentiferous galena attracted attention, but was not of any importance. Other veins are known at Lubeck, Me., and in various parts of New Hampshire and Vermont. For a time small lodes in the slates of Columbia County, New York, were unsuccesssfully exploited, of which the Ancram mine is of historic interest. Although these galena veins are numerous, they are not to be taken too seriously.'' 2.05.06. (3) Southeastern Pennsylvania. Veins on the contact of Archean gneiss and Triassic sandstone and diabase. These were referred to under Example 216. As noted by Whit- ney, the copper is especially strong in the sandstone, and the lead in the gneiss. Trap dikes are abundant, and the eruptive phenomena in connection with them may have occasioned the activity of the circulations which filled the veins. The Wheat- ley mine is best known. It has afforded a great variety of lead 'I.e. Beck, Mineralogy of New York, p. 45. E. Emmons, "Geology of the Second District," iV. Y. Geol. Survey, 1842. G. Hadley. "Crystal- lized Carbonate of Lead at Rossie," Amer. Jour. Sci., ii., 11., 117. F. L. Nason, " Calcite from Rossie," Bull. 4., N. Y. State Museum, 1888. J. D. Whitney, Metallic Wealth. Rec. ' B. K. Emerson, Geology of old Hampshire Co., Mass., comprising Franklin, Hampshire and Hampden counties. Monograph XXIX, U. S. Geol. Survey. See also Bulletin 126. — Idem. C. A. Lee, "Notice of the Ancram Lead Mine," Amer. Jour. Sci., i., VIII., 247. A. Nash, "Notice of the Lead Mines and Veins in Hampshire County, Massachusetts," Amer. Jour. Sci., i., XII., 238. R.H.Richards, "The Newburyport Silver Mines," Trans. Amer. Inst. Min. Eng., HI., 442. B. Silliman, at South- ampton, Mass Brace's Journal of Mineralogy, I., 65. J. D. Whitney, Metallic Wealth. 228 KEMP'S QBE DEPOSITS. minerals, especially pyromorphite. The mines iiave not been worked in years.' 2.05.07. (4) Davison County, North Carolina. Veins in taloose slate were formerly exploited, but are now little known, except as having furnished beautiful crystals of oxidized lead minerals.^ 3.05.08. Example 226. Sullivan and Ulster Counties, New York. Veins along a hne of displacement on the contact between the Hudson Eiver slates and the sandstones of the Me- dina stage (Shawangunk grit), carrying galena and chalcopy- rite in a quartz gangue; or else gash veins filled with the same in the grit. These mines formerly produced considerable lead and copper, but are now best known for the excellent quartz crystals which they have furnished to all the mineralogical col- lections of this and other lands.^ 2.05.09. Example 23. The Disseminated Lead Ores of Southeast Missouri. Galf^na, accompanied by varying amounts of nickeliferous pyrite, disseminated through dolomitic lime- stone of Lower Silurian or Cambrian age, its determination be- ing in dispute. The dolomitic limestone is called the St. Jo- seph limestone by Arthur Winslow,* who considers it Lower Silurian. C. R. Keyes' has designated it the Fredericktown, and classifies it with the Cambrian. As shown in the accom- panying map, which is based on one by Winslow, the mining districts are distributed along a line running west of north. At the north is Bonne Terre, the most productive of all up to the present. A few miles south is the Flat River district, in- cluding Desloge. The next is Doe "Run, and then after a con- siderable interval Mine la Motte. Recently prospects have been opened, near Fredericktown. Much drilling has been done between these centers, but without notable results. The geo- logical relations are simple. On the south and southwest aio ' H. D. Rogers, Geol. of Penn., II., 701; aXs,o Anier. Jour. Sci., ii., XVI., 433. J. D. Whitney, Metallic Wealth, p. 396. ' J. C. Booth, "Analyses of Various Ores of Lead, etc., from King's Mine, Davison County, North Carolina," Amer. Jour. Sci., i., XLI., 348. W. C. Kerr, Geol. of North Carolina, p. 389. = J. D. Whitney, Metallic Wealth. W. W. Mather, N. Y. State Survey, Report on First District, 358. • Bull. 132, U. S. Geol. Survey, p. 11. ' "Mine la Motte Sheet," in Mo. Geol. Survey, Vol. IX., Report 4, p. 48 LEAD ALONE. 329 the Archean granites, porphyries and diabase dikes, earlier mentioned in connection with the specular hematites of Iron Mountain and Pilot Knob. Scattered knobs of them are also GEOLOGICAL MAP OF THE SOITHEASTERN .1IISS0CRI n~~\DI83E3HNATED LEAD ORE Sl'B-DISTRICT From a Colored Map by Arthur Winslow 1895. In Bulletin 132 U.S. Geol. .Survey Potoai . Limestone Lower \^^ stJoseph Silunan .(^3 Limestone .Cambrian?)/ ^ ,, ^^ ^ * ^LaMotte Sandstone r fT^Xl Granite Archean < Fig. 75. met to the eastward. On the granites and porphyries rests the La Motte sandstone, of variable thickness, but possibly reach- ing 400 feet, according to Winslow. Conformably on the sand- 230 KEMP'S OBE DEPOSITS. stone lies the St. Joseph dolomitic limestone, the ore-bearing formation. It varies from 200 feet at Mine la Motte to 600 feet at Bonne Terre. It varies from shaly to massive struct- ures, and is often coarsely granular in texture. In rock of the latter character, and, in the southern districts, usually not far above the sandstone, is found tha ore. At Bonne Terre, however, the ore is a long distance above the base. The ore is galena, often mingled with more or less pyrites, and as a rule it is disseminated through the limestone so as to form an inte- gral part of the rock. It also forms sheets sometimes along joints and stratification planes, and seems to favor the darker or more bituminous varieties of the dolomite. At Mine la Motte certain "diggings" or mines seem to have some connec- tion with, a local fault, but others do not indicate such rela- tions, and elsewhere small fissures, or joints, often so tight as only to be revealed by the dropping of water, are the only cracks of any kind apparent. The St. Joseph formation lies very flat, and is practically devoid of fossils. Above it comes a cherty limestone, called the Potosi by Winslow (Leseur by Keyes). It is widespread, but has no immediate connection with the ore. The ore bodies are in the nature of impregnations of the wall rock which extend fairly parallel with the stratification and are of varying thickness. They fade out gradually into low grade or barren rock. They may be cut at several horizons by the shafts or drill holes. One at Bonne Terre has been mined, according to Winslow, over an area nearly three-quarters by one half of a mile, and ore is known through alrnost 250 feet vertical thickness. The yield to date has been about a quarter of a million tons of lead. Throughout the districts the shafts are not deep, seldom reaching 400 feet. The ore as mined con- tains from 7 to 10 per cent, galena, although blocks of over a ton of the pure sulphide have been taken out. The formation of these ore bodies is a very obscure question. The writer in 1887 applied to them the views that had been early advanced by Whitney for the gash veins of the Upper Mississippi, namely, that decaying marine vegetation had pre- cipitated the sulphides from sea water. This is very doubtful, as traces of algae, or any other fossils, are extremely rare. W. P. Jenney in 1893 referred them to solutions uprising along LEAD ALONE. 331 faults, which were thought to cut the ore bodies, and from which the mineralizing waters had spread laterally through the porous beds. The fault at Mine la Motte along which the ore occurs has been earlier cited as giving some support to this view, although right at the fault the ore bodies tend to grow lean. Elsewhere faults are insignificant so far as known. Winslow favors the descent of solutions from above, and thinks that the sulphides have been supplied by the weathering of overlying strata, now in large part removed. These regions have been land since the early Carboniferous times, and the superficial decay has been enormous. Lead-bearing solutions, it is thought, have filtered downward through the joints, faults and small cracks, and have deposited their dissolved materials bv replacement of the limestone. The conduits seem, how- ever, insignificant when compared with the ore bodies, and it is evident that all the expiapations thus far suggested involve difficulties. In the Mississippi Valley in this portion of the country the Lower Carboniferous and earlier rocks contain lead over an area of more than 3,000 square miles. Aside from these dis- seminated orep, zinc is always associated with the lead ; but in southeastern Missouri it is practically unknown in the depos- its of the disseminated type. There are, however, in the neigh- boring districts several mines, such as the Valle, which are closely analogous to the gash veins later described, and which do contain zincblende. The history of Mine la Motte dates back to the early part of the eighteenth century, when this region figured largely in John Law's Mississippi bubble. The mine is said to have furnished lead for bullets during the war of the Revolution.^ ' A bibliography of the lead and zinc regions of Missouri, by Arthur Winslow, will be found in the Reports of the Missouri Geol. Survey, VII., Part II., p. 743. It comes down to 1894. A bibliography of Missouri geology in general was prepared by F. A. Sampson and issued as Bulletin ii of the Mo. Geol. Survey, in 1890. A revised edition by C. R. Keyes appears in Vol. X., of the Survey, p. 221, and comes down to 1896. The more important or the more recent papers are given below: G. C. Broad- head, '■ The Southeastern Missouri Lead District," Trans. Amer. Inst. Min. Eiig., v., 100. Rec. J. R. Giige, " Occurrence of Lead Ores in Missouri," Idem, III., 116; also Oeol. Survey of Missouri, 18T3-74, pp. 30, 603. W. P. Jenney, "The Lead and Zinc Depo.sits of the Mississippi Valley," Irans. Amer. List. Min. Eng., XXII., 171, 631, 1893. J. F. Kemp, "Notes on the 232 KEMP'S ORE DEPOSITS. 3.05.10. The great increase in lead production in the United States came about 1880, with the opening of the Leadville ore bodies. From 1877 until 1881 Eureka, Nev., was an important source, but since then it has greatly declined. Utah has pre- served a fairly uniform production since the early seventies. Lead from all sources is here mentioned, although lead- silver ores are subsequently treated. The amounts are in tons of 2,000 pounds. For detailed statistics see the annual volume on The Mineral Industry (New York: Scientific Publishing Company) and the Annual Reports o* the Director of the U. S. Geological Survey. The figures for 1896 are taken from the Eighteenth Annual Report, Part V., p. 240. 1880. 1890. 1896. Missouri, Kansas, Wisconsin, Illinois 37,690 55,000 51,887 Colorado 35,674 60,000 44,803 Nevada 16,659 3,500 1,173 Utah 15,000 34,000 35,578 Idaho, Montana 34,000 57,733 Elsewhere 3,803 15,994 6,333 97,825 181,494 197,496 From 80 to ^5% of the total product is from lead-silver ores. Ore Deposits, etc., qf Southeastern Wissouvi," School of Mines Quarterly, October, 1887,74; April, 1888, 313. C. R. Keyes, ■ ' The Mine la Motte Sheet," Geol. Survey of Missouri, IX., Report 4, 1896. A. Litton, Second Ann. Rep. of the First Geol. Survey of Mo., 13-64, 1854. James E. Mills, Report on the Mine la Mo tte Estate, New York, 1877. H. S. Munroe, ' ' The New Dressing Works of the St. Joseph Lead Co., at Bonne Terre, Mo.," Trans. Amer. Inst. Min. Eng., XVIL, 659, 1888. J. W. Neill, "Notes on the Treatment of Nickel-Cobalt Mattes at Mine la Motte, " Idem, XIII. , 634. F. Posepny, "On Mine la Motte," Genesis of Ore Deposits, p. 107; Trans. Amer. Inst. Min. Eng., XXIII., 303, 1893. H. A. Wheeler, "On Southeast Missouri Lead Mines, The Colliery Engineer, 1893. C. P. Williams, "Industrial Report on Lead, Zinc and Iron in Missouri," Jefferson City, 1877. Arthur Winslow, "Lead and Zinc Deposits of Missouri," 3 vols., Missouri Geol'. Survey, VII., Parts I. and II., 1894. A very complete book on lead and zinc in general. Fairly complete bibli- ography. Part II., p. 748. A fuller one by F. A. Sampson will be found in Bulletin 2 of the Mo. Geol. Survey, 1890. Arthur Winslow, "Lead and Zinc Deposits of Missouri," Trans. Amer. Inst. Min. Eng., XXIV., 634, 981, 1894. "Notes on the Lead and Zinc Deposits of the Mississippi Valley and the Origin of the Ores," Jour. Geol., I., 613, 1893. "Report on the Iron Mountain Sheet," Mo. Geol. Survey, IX., Report 3, p. 33, relates to Doe Run. "The Disseminated Lead Ores of Southeastern Missouri," Bul- letin J3S, U. S. Geol. Survey, 1896. Rec. The best brief account, "His- torical Sketch of Lead and Zinc," Eng. and Min. Jour., November 17, 34, 1894 ; January 19, 1895. CHAPTER VI. LEAD AND ZINC. 3.06.01. Example 24. The Upper Mississippi Valley. Gash veins and horizontal cavities (flats), principally in the Galena and Trenton limestones of the Upper Mississippi Val- ley, and containing galena, zincblende, and pyrite (or marca- site), with calcite, barite, and residual clay. The deposits are found in southwest Wisconsin, eastern Iowa, and northwestern Illinois. The greater portion of the productive territory lies in Wisconsin, and covers an area which would be included in a circle of sixty miles radius, whose limits would pass a few miles into Illinois and Iowa. A low north and south geanti- cline runs through central Wisconsin, dating back to Arche- an times and called by Chamberlin "Wisconsin Island." On its western slope the Cambrian and Lower Silurian rocks are laid down, and these in the western limit of the lead dis- trict pass in the adjoining States under the Upper Silurian. They are folded also in low east and west folds, but in the aggre- gate the whole series dips very gradually westward. The chief east and west fold forms the south bank of the Wisconsin River, and may have been the cause that deflected it from a southerly course. The easterly part of the lead region is 350 feet higher than the western, and the northern is 500 feet above the southern. The general slope is thus southwesterly. 2.06.02. The Galena limestone is a dolomite reaching 250 feet in thickness. On the hilltops left by erosion Maquekota (Hud- son River) shales are seen. The Galena has shaly streaks, which have largely furnished the residual clay of the cavities. There are also cherty layers and sandy spots. Under the Ga- lena lies the Trenton, from 40 to 100 feet thick, and made up of an upper blue portion, which is a pure carbonate of lime, 23i KEMP'S ORE DEPOSITS. and a lower buff portion that is magnesian. The upper portion of the blue has a band of shale locally called the " Upper Pipe Clay," and the pure, cryptocrystalline linaestone under this is called "Glass Rock." The blue contains much bituminous matter. The buff is locally called "Quarry Rock," and is prolific in fossils. Under the Trenton lies the St. Peter's sand- stone, 150 feet below which is the Lower Magnesian (Oneota), 100 to 250 feet, and still lower the Potsdam, averaging 700 to 800 feet. The Potsdam rests on the quartzites and schists of the Archean. The ore bodies especially favor the shallow, syn- ^^^^^BB Fig. 76. — Ganh veins, fresh and disintegrated. The heavy black shading in- dicates galena. After T. G. Ohamherlin, Oeol. Wis. , Vol. IV. , 454. clinal depressions of the east and west folds. They occur in crevices, the great majority of which run east and west. The productive ground comes in spots, which are separated by stretches of barren ground. The lead ores are chiefly produced by the crevices in the Upper Galena. In the Lower Galena the zinc ores become relatively more abundant, and they are also in the Trenton. The ores do not extend in any apprecia- ble amounts either above or below these horizons. The upper deposits favor the vertical gash vein form ; the lower tend rather to horizontal openings, called flats, which at the ends LEAD AND ZING. 2;Jo dip down (pitches) and often connect with a second sheet (flat) lying lower. There are several minor varieties of those two main types of cavity, which mainly depend for their differences on the grade of decomposition, which the walls have under- gone, and whether there was an original opening, or only a brecciated and crushed strip. Chamberlin cites twelve varie- ties in ■'.ll, some of which are based on rather fine distinctions. A. G. Leonard has described a sheet of galena, at the Lansing mine, in Iowa, that was three to four inches thick, 25 to 35 feet high, and over 1,000 feet long. Some of the Iowa crevices have proved remarkably persistent on the strike. H. F. Bain has called the writer's attention to the Lansing mine in Allamakee, Iowa, which has yielded lead ore without any zinc whatever. Galena ^ 1 " 5 — -• Fig. 77. — Idealized section of "fiats and pitches," forms of ore bodies in Wis- consin. After T. 0. Chamberlin, Geol. Wis., Vol. IV., 458. and which is peculiar in that it occurs in the Oneota or Lower Magnesian limestone, and is therefore below the main product- ive horizon of the gash veins. The crevice also trends north and south as against the usual east and west strike of the gash veins. 3.06.03. The cavities were referred by J. D. Whitney to joints, formed either by the drying and consolidating of the rock, or by gentle oscillations of the inclosing beds. The later work has largely corroborated this, and they are generally thought to be chiefly caused by the cracks and partings formed by the gentle synclinal foldings. Such cavities have usually been enlarged by subsequent alteration of the walls. Whitney 336 KEMP'S ORE DEPOSITS. also essentially outlined the explanation of origin, which has been more fully elaborated by Chamberlin. Both these writ- ers have urged that the ores could not have come from below, for the lower rocks are substantially barren of them. The con- clusion therefore follows that they were deposited in the lime- stones at the time of their formation. The source of the ores is placed in the early Silurian sea, from which it is thought they were precipitated by sulphuretted hydrogen, exhaled by decay- ing seaweeds, or similar dead organisms on the bottom. In carrying the idea further, Chamberlin has endeavored to re- produce the topography of the. region in the Lower Silurian times and to indicate the probable oceanic currents. These are conceived to have made an eddy in the lead district, and to have collected there masses of seaweed, etc., resembling the Sargasso Sea. While interesting, this must be considered very hypothetical. When the sulphides became precipitated they were doubtless finely disseminated in the rock, and were gradually segregated in the crevices. The sulphurous exhala- tions from the bituminous limestones may have aided in their second precipitation. W. P. Jenney in 189.S referred the east and west fissures, mentioned above as crevices, to faults, which are as a rule not far from the vertical, but may dip 35° to 40°. The smaller north and south series are considered to be likewise due to faulting, but to be earlier, as they are thrown by the east and west set. The displacement from the latter is horizontal rather than vertical. The intersections of the two sets are said to be especially favorable to ore bodies. The name "run" is applied to the ore body, it having been adopted from southwest Missouri. The ore is thought to have been deposited along the fault fissures by uprising solutions, which have spread laterally into those beds, that, from their chemical composition (being dolomitic) or their open structure, were fa- vorable to them. In the same year (1893), W. P. Blake discussed these ore bodies, paying a tribute to Percival's early views on faulting as a cause of the veins, and describing its obscurity and the difficultA' of demonstrating its presence. Blake, however, cited the Helena mine near Shullsburg as an instance in which the mineralization did occur near a pair of faults. Blake also lays stress upon the presence of thin seams of rich bituminous LEAD AND ZINC. 237 shale, in layers usually about as thick as cardboard, which occur in a richly fossiliferous limestone at the top of the Trenton, just beneath the ore-bearing "Galena" dolomite, and which are regarded as very probable factors in the precipita- tion of the ore. The mining region, it should be emphasized, lies within the peculiar, unglaciated area, which is one of the notable geologi- cal features of this portion of the country. It has, therefore, long been exposed to the atmospheric agents, and has not been denuded of the residual products of decay as have the glaciated districts. The papers of Jenney and Blake led to a notable discussion of these ore bodies, and to wide divergence of views regarding them. Arthur Winslow, in connection with his more extended treatment of those in Missouri, has urged that the sulphides have been supplied from the overlying strata, during the exten- sive, subaerial decay to which these have been subjected. Pass- ing into solution they are thought to have percolated into the crevices and to have been precipitated. A. G. Leonard, in his study of the Iowa veins, reaches a similar conclusion, but on account of the impermeability of the Maquekota shales, restricts the source of the ore to the Galena dolomite. The frequent occurrence of the ores in stalactites projecting downward from the roof of a chamber gives support to these views. Leonard favors Chamberlin's view of the precipitation from a sup- posed Sargasso Sea of the Ordovican times. The paragenesis of the minerals shows the following suc- cession: (1) Pyrite, (3) Galena, (3) Pyrite; or (1) Pyrite, (2) Blende, (3) Galena, (4) Pyrite; or (4) Calcite. The ores, espe- cially of zinc, are often oxidized, and afford considerable cala- mine and smithsonite. Some oxidized copper ores are produced at Mineral Point, formed by the alteration of chalcopyrite. In the early mines lead alone was sought, but of late years the zinc has been produced in greater quantities, and is more valu- able than the lead.' Smithsonite is found in commercial quan- tities as well as blende. ' Wisconsin.— J. A. Allen, "Description of Fossil Bones of Wolf and Deer from Lead Veins. ", Amer. Jour. Sci., iii., II., 47. W. P. Blake, "The Mineral Deposits of Southwest Wisconsin," Trans. Amer. Inst. Min. ^Jigr., XXII., .I.i8, 189.S. Rec. Amer. Geol., XII., 337, 1893. " The Ex- 338 KEMP'S ORE DEPOSITS. 2.06.04. Example 34a. Washington County, Missouri. Gash veins in the Potosi cherty limestone of eastern Missouri in the same region as the disseminated ores of Example 23, and containing galena, barite (locally called "tiff"), calcite, and residual clay. The cavities are described by Whitney as re- sembling in all respects the gash veins further north, which, however, lie in rocks higher in the geological series. These mines were the earliest worked, but have been given up since the istence of Faults and Dislocations in the Lead and Zinc Regions of the Mississippi Valley, with Observations upon the Genesis of the Ores," Idem, 621. Rec. This last paper was written in discussion of one by W. P. Jenney, cited below. "Wisconsin Lead and Zinc Deposits, " Bull. Geol. Soc. Amer. , V. , 2o, 1893. ' ' Progress of Geological Surveys in the State of Wisconsin — a Review and a Bibliography," Trans. Wis. Acad. Sci., IX., 22,'5. T. C. Chamberlin, Wis. Geol. Survey, IV., 1883, p. 367. Rec. E. Daniels, " Geology of the Lead Mines of Wisconsin," Amer. Asso. Adv. Sei., VII., 290; Wis. Oeol. Survey, 1854; E7ig. and Min. Jour., July 6, 13, 20, 27, August 3, 10, 24, October 5, 1878, December 14, 1889, ,122. James Hall, "Notes on the Geology of the Western States," Amer. Jour. Sci., i., XLII., .51, W. H, Hobbs, "A Contribution to the Mineralogy of Wiscon- sin," Bull. Univ. of Wis., Science Series I., 114; see aXao Zeitseh. fi'ir Kryst., XXV., 357, 1895. J. T. Hodge, "On the Wisconsin and Missouri Lead Region," Amer. Jour. Sci., L, XLIII., 35. R. D. Irving, "Mineral Re- sources of Wisconsin," Trans. Amer. Inst. Min. Eng., VIII., 478. E. James, "Remarks on the Limestones of the Mississippi Valley Lead Mines," Phila. Acad. Set, V., Part I., p. 51. W. P. Jenney, "The Lead and Zinc Deposits of the Mississippi Valley," Trans. Amer. Inst. Min. Eng., XXII., 171, 631, 1893. Rec. J. Murrish, Report on the Lead Regions, 1871, as commissioner fortheir survey. D. D. Owen, "Report on the Lead Region," U. S. Senate Documents, 1844. J. G. Percival, Wis. Oeol. Sur- vey, 1856. Squier and Davis, " Historical Account," Smi<7i.sortian Contri- butions, Vol. I., p. 208. M. Strong, Wis. Geol. Survey, 1877, I., 687; II., 645, 689. J. D. Whitney, Wis. Geol. Survey, 1861-62, I., 331. Rec. Me- tallic Wealth, p. 403, 1856. "On the Occurrence of Bones and Teeth in the Lead- bearing Crevices," Amer. Assoc. Adv. Sci., 1859. Arthur Wins- low, "Lead and Zinc Deposits of Missouri," Trans. Amer. Inst. Min. Eng., XXIV., especially 677-690, 1894. See also Vol. VI. of Geol. ^'urvey of Mo., 185-150, 1894. Illinois. — J. Shaw, Oeol. Survey of Illinois, 1873, II., 840. J. D. Whitney, Idem, 1866, I., 153. Iowa. — A. G. Leonard, "Lead and Zinc Deposits of Iowa," loiva Oeol. Survey, VI., 1896. Rec. "Origin of the Iowa Lead and Zinc Deposits," Amer. Oeol, XVI., 288, 1895; Eng. and Min. Jour., June 27, 1896, 614; Colliery Engineer, XVII., 131, 1896. C. A. White, Iowa Geol Survey, 1870. II., p 339. J. D. Whitney, Idem, 1858, I., p. 422. LEAD AND ZING. 339 price of lead has been at present figures (1875 and subse- quently). The ore wa's obtained from pockets, caves, irregular cavities, and from the overlying residual clays. This vchole region has been exposed and above water since the close of Carboniferous times, and has suffered enormous surface decay (see R. Pumpelly, Tenth Census, Vol. XV., p. 12, and Oeol. Soc. Amer., Vol. II., p. 20), which has left a mantle of residual clay spread widely over its extent. In this, more or less float mineral occurred. The mines were located in Washington, Franklin, Jefferson and St. Francois counties.' Very similar deposits in rocks of about the same geological horizon also occur in the central part of the State, in the counties near the Osage River. The district has been called the Central by Winslow. 2.06.05. Example 246. Livingston County, Kentucky. Veins in limestone of the St. Louis stage of the Lower Carbon- iferous, containing galena in a gangue of fluorite, calcite and clay. The ore bodies have never been well described, and no very accurate account can be given. They are found in Liv ingston, Crittenden, and Caldwell counties, Kentucky, in that portion of the State lying south of the Ohio River and east of the Cumberland. While limestone always forms one wall, a sandstone of geological relations not well determined forms the other. The veins run from two to seven feet wide and in in- stances are richer in their upper portions than in the lower. As yet they are of greater scientific than practical importance. Some galena occurs also in irregular cracks in the limestone. As a possible indication of a stimulating cause for the forma- tion of the veins, the interesting dike of mica-peridotite may be cited, which has been described by J. S. Diller.^ The dike occurs in the same fissure with a vein of fluorspar.' ' Compare the older references under Example 23, and the following : A. Litton, Second Ann. Rep. Missouri Oeol. Survey, 1854. J. D. Whitney, Metallic Wealth, p. 419. Arthur Winslow, "Lead and Zinc Deposits of Missouri," Vols. VI. and VII. of Mo. Oeol. Survey; Trans. Amer. Inst. Min. Eng., XXIV., 634. ' "Mioa-Peridotite from Kentucky," Airier. Jour. Sci., October, 1892. ' S. F. Emmons, "Fluorspar Deposits of Southern Illinois," Trans. Amer. Inst. Min. Eng., February, 1892. C. J. Norwood, "Report on the Lead Region of Livingston, Crittenden and Caldwell Counties," Ken- tucky Oeol. Survey, 1875, New Series, Vol. I., p. 449 MO KEMP'S ORE DEPOSITS. 3.06.06. Example 25. Southwest Missouri. Zincblende and very subordinate galena with their oxidized products, asso- ciated with chert, residual clay, calcite, a little pyrite and bitu- men, in cavities of irregular shape and in shattered portions of Subcarboniferous limestone. Across Missouri, from a point south of St. Louis, and including the country as far to the northwest as Sedalia and Glasgow, a broad belt, called the Ozark uplift, extends southwesterly into Arkansas. It has formed a great plateau in central and southern Missouri, and consists largely of Silurian rocks. These have a fringe of Devonian on the edges and dip under the Lower Carboniferous. The plateau reaches 1,500 feet above the sea in Wright County, b\it on the limit is succeeded by lower country. To the southwest it drops somewhat, with Lower Carboniferous strata outcropping, which in Kansas are overlain by the coal measures. The surface then rises again in the prairies. At the edge of the plateau is a trough, in whose bottom the Lower Carbonifer- ous strata are cut by the Spring River, which flows southwest- erly from Missouri across the western State line into Kansas, and has a general direction parallel to the western limits of the uplift. It receives tributary streams on each bank, which cut the strata in strongly marked valleys, and afford good expo- sures. Those on the east bank, from south to north, are Shoal Creek, Short Creek, Turkey Creek and Center Creek, while from the west come the Brush, Shawnee, and Cow creeks, all in Kansas. Along the first mentioned creeks the principal mining towns are situated, but others are found on the minor streams. They extend through an area fifteen miles broad from east to west, and twenty-five miles from north to south. Newton and Jasper are the most productive counties in Mis- souri, while Cherokee County, in Kansas, also contains nota- ble mines. Undeveloped districts are recorded in Arkansas, but apparently at a lower geological horizon. The ore occurs in the Keokuk or Archimedes limestone of the Lower Carbonif- erous. A generalized section of the rocks, according to F. L. Clerc, is as follows : On the higher prairie, some 15 feet of clay or gravel; 10 feet of flint or chert beds; 40 feet of lime- stone with thin beds of chert ; 60 feet of alternating layers of limestone and chert; 100 feet and more of chert, sometimes chalkj' with occasional beds of limestone; 325 feet in total. In LEAD AND ZINC. ■Ul basins and extensive pockets in these rocks, deposits of slates With small coal seams are found, of undetermined geological relations. The large bed of limestone of the section affords a Qatum of reference in relation to which the ores may be de- 3%Found Ore . ^ 85% 34% 75/aFo\ind 40 to 60 ft. Lena & Zinc BO%Foundj No Ore 60/SFound Ore jO'^Found Zinc Oi-o at rOTSto 1100 fl. i i I I The Flint and Llmcstonq samo-as Bt the surface. Fig. 78. — Chart showing the results of deep borings in the Joplin district. Mo. From, the Engineering and Mining Journal, March 18, 1899, p. 331. scribed. A few minor, shallow deposits occur in the flints over it. In the limestone the ores are associated with a gangue of dolomitic clay and residual flint. They occupy irregular cavi- ties or openings, locally known as circles, spar openings, and 242 KEMP'S ORE DEPOSITS. runs. (Clerc.) Below the limestone the ore is fonnd in "sheets, bands, seams, and pockets," and filling in the inter- stices of a breccia of chert, which has been formed by the breaking down of the chert layers on the solutions and removal of the interbedded limestones. There are districts where the overlying bed of limestone has also disappeared, and they then lack it for a capping. The deposits extend to considerable depths below the position of the limestone. The present mines have not demonstrated as yet their limit of depth. At times the ore is associated with a later-formed quartz rock that has coated and filled the cavities of the breccia. Although the mining is, as yet, comparatively shallow, the results of a large number of deep bore-holes are now available, and are shown in the accompanying Fig. 78. From the chart it is evident that there are four ore-bearing horizons distributed down to a depth of about 1,100 feet. Below this, and down to 2,005 feet, no ore was met. The holes were all drilled in Jas- per County, and near Joplin and Webb City. 2.0G.07. The removal of the interbedded layers of limestone and the caving in of the associated cherts have been the princi- pal causes of the formation of cavities. Adolph Schmidt re- ferred the shrinkage to the dolomitization of pure lime carbon- ate, an idea that has had extended adoption. Dolomitization has also an important part in causing the general porosity. Schmidt traced five periods in the geological history of the ore bodies: 1. Period of deposition of the rocks. 2. Period of dolomitization of certain strata and bf principal ore deposition. 3. Period of dissolution of part of the limestone, of breaking down of chert, and of continued but diminishing ore deposition. 4. Period of regeneration, secondary deposition of carbbaate of lime and quartz, and continued ore deposition. 5. Period of oxidation. Schmidt's work was done in 1871-72. Since then the in- creased development of the mines has afforded greater opportu- nities for observation. Haworth, in 1884, referred, with much reason, the shattering of the chert in certain areas to oscilla- tions of the strata, and Clerc, in 1887, emphasized particularly the dissolving action of water. It is a hard problem to dis- cover the original source of the metals. The earlier writers said nothing of this subject, or else, as in Haworth's paper, dis- LEAD AND ZINC. 243 cussed a possible precipitation from the ocean, or, as in Clerc's, referred them to the pockets of slate and coal. In 1893, at the Chicago meeting of the American Institute of Mining Engi- neers, W. P. Jenney presented an abstract of the results of his work while detailed by the U. S. Geological Survey to study these ore deposits. As will appear in the abstract of the paper given below, the ores are supposed to have come up through fissures of displacement, and hence from below. These con- ^. , / ), , , ■..'.■•/,■/•//'•,-'' Pi'obable flint floor of VIZ (,' v'*-' y,!^\! v' ^•-■'•JJJ^'^ ^\/j J^/Jw^''v^^\r^'^''^''^''y^' ore.deposit. Typical ziNC-BLENOE ORE'BODY NEAR Webb City, Mo. Vertical Section. -^ SubcarboniferouB Limestone ^^y^'' Flint rocK ^^^^linc-blande ore-bodies Worked out part of ore-deposit. Qalenite ir^iasures & bedding-planes In limestone Fig. 79. — Vertical section of a typical zincblende ore body, near Webb City, Mo. After C. Henrieh, I'rniis. Amer. Inst. Mill. Eng., XX., p. 14. elusions have been controverted by others, on account of the difficulty in proving the existence of faults when evidence of displacement is so obscure. In Jenney's paper all the lead or lead and zinc regions of the Mississippi Valley are considered together. They are described as occurring along three lines of upheaval. The region of Wisconsin and Iowa is on the flanks of the Archean "Wisconsin Island" of Chamberlin, re- ferred to above under 2.06.01. The southeast and southwest 344 KEMP'S ORE DEPOSITS. Missouri regions are on the Ozark uplift, while a minor argen- tiferous galena district is on the line of the Ouachita uplift of Arkansas and Indian Territory. The formation of the ore bod- ies in the first three of these is regarded as having been in gen- eral the same. They are thought to have originated from up- rising solutions, which came through certain principal fissures, and spread laterally into strata favorable to precipitation. In southwest Missouri this was the Cherokee limestone of the Lower Carboniferous. In its unaltered state it is an extremely pure carbonate of lime. It has a maximum thickness, where not eroded, of 165 to 200 feet, and contains many interbedded layers of chert. Much organic matter, and more or less bitu- men, are also at times present. The limestone seems to have been raised above the ocean level at the close of the Lower Carboniferous, and to have remained for a long period exposed to the atmospheric agents. Much caving in of unsupported layers of chert and much attendant brecciation resulted. The general stratum became quite open and cellular in certain portions. At a later period, supposed from several indications to be at the close of the Cretaceous, dynamic disturbance oc- curred, which along certain lines produced fissures, sometimes parallel, sometimes intersecting. Solutions arose through these which dolomitized much of the remaining limestone and caused additional porosity. Zinc and lead ores were afforded, and where the conditions were favorable they spread laterally from the fissures and deposited the sulphides in the cellular rock or replaced the limestone itself. The intersection of crossing fis- sures is a frequent point of deposition, and at times parallel master fissures have given a wide area of impregnation. This form of ore deposit is called a run. The runs are from 5 to 50 feet in height, 100 to 300 feet long, and 10 to 50 feet across. At Webb City thej' are even larger. As a general thing the ore is in the interstices of the brecciated chert, but it is also in limestone and dolomite, and associated with a silicified form of the insoluble residue left by the solution of the limestone, which Jenney calls "cherokite." All the ores require con- centration. Galena usually occurs near the surface, while blende is more abundant in depth. Cadmium is at times pres- ent in the blende in notable amount. In 1894, the verj' thorough report of Arthur Winslow on lead LEAD AND ZINC. 245 and zinc in Missouri, and incidentally elsewhere in the world, appeared, and likewise a briefer account before the American Institute of Mining Engineers. Winslow gives in the large volumes the roost detailed work of reference yet issued, and reaches a quite different view regarding the derivation and for- mation of the ores. He emphasizes the fact that the region has long been a land area, in fact, ever since the close of the Lower Carboniferous times. The subaerial decay has therefore been excessive and a considerable thickness of overlying rock has gone. This has favored the formation of caves, sinks and un- derground waterways, which have often collapsed. Extremely careful analyses of fresh and large samples of the various lime- stones associated with or overlying the lead and zinc deposits of the State were made, as well as of a series of the Archean rocks, from which, in the course of long erosion, the others are supposed to have been derived. The Archean rocks yielded 0.00197 to 0.0068 per cent, lead (.04 to .136 pounds per ton), and 0.00139 to 0.0176 per cent, zinc (.028 to .352 pounds per ton); the Silurian Magnesian limestones, a trace to 0.00156 per cent, lead (up to .03 pounds per ton); and a trace to O.Ol.oOs per cent, zinc (up to .307 pounds per ton); the Lower Carbon- iferous limestones, a trace to 0.00346 per cent, lead (up to .07 pounds per ton), and a trace to 0.00256 per cent, ziinc (up to .05 pounds per ton). Winslow concludes from the above data and observations and from the difJSculty, if not impossibilitj-, of discovering actual evidence of fault fissures, that the ores have become concentrated in the shattered rock by the down- ward percolations of lead and zinc-beading solutions, which have derived the metals from the overlying and largely decom- posed strata. 2.06.08. Some interesting alterations of the minerals have occurred, which have changed the blende to smithsonite and calamine. In one case a secondary precipitation of zinc sul- phide has yielded a white, amorphous powder, which is of very recent date. With the original precipitation of the blende, the asphaltic material noay have had something to do. In the matter of production, W. P; Jenney fixes the ratios of the blende, galena, and pyrite at about 1,000 : 80 : 0.5.^ ' MissoTTEi. — G. C. Broadhead, "Geological Histor}' of the Ozark Up- lift,' Amer. Oeol, III., 6. H. M. Chance, "The Rush Creek (Arkansas) 346 KEMP'S ORE DEPOSITS. 2.06.09. Other zinc and lead deposits are known in central Missouri generallj'- resembling the above quite strongly, but of less economic importance. Some, however, are described by Schmidt as conical stockworks. They sometimes are found in Lower Silurian strata. fig. 5 Fig. 80. — Geological section of the Bertlia zinc mines, Wythe County, Va. After W. H. Case, Trans. Amer. Inst. Mitt. Eng., XX [I., p. 530. 2.06.10. Both the mines of Example 25 and those of Exam- ple 24 were originally worked for lead, and the zinc minerals Zinc District," Tratis. Amer. Inst. Mi it. Eng., Vol. XVIII., p. 505, 1890. F. L. Clevc, Geological description of the mines in a statistical pamphlet on the Lead and Zinc Ores of Southwest Missottri Mines, p. 4, published by J. M. Wilson, Carthage, Mo., 1887. Reo. See also Eng. and Mitt. Jour., June 4, 1887, p. 397; " Zinc in the United States," Mineral Resources, 1882, p. 368. G. T. Cooley, "Dressing Lead and Zinc Ores in Kansas," Eng. and Min. Jour., July 7, 1895, p. 9. Eng. and Min. Jour., November 3, 1888, p. 389 ; March 8, 1890, p. 386. ' ' Distribution of Lead and Zinc near Joplin, Mo.." Idetti, March 18, 1891, 331. Rec. E. Haworth, " A Contribu- tion to the Geology of the Lead and Zinc Mining District of Cherokee Coiinty, Kansas, Oskaloosa, Iowa," 1884. C. Henrioh, " Zinoblende Mines and Mining near Webb City, Mo.," Trans. Amer. Inst. Min. Eng., XXL, p. 3, 1892; Eng. and Min. Jour., June 4, 1893. J. R. Holibaugh, "The Lead and Zinc Mining Industry of Southwest Missouri and Southeast Kan • .sas," Eng. and Min. Jour.. LVIII., 1894, 199, 394, 413, 487, 460, 485, 508 and 535 Also issued as a separate book by the Scientific Publishing Co. , 50 cents. W. P. Jenney. ' ' Lead and Zinc Deposits of the Mississippi Valley, ' Trans. Amer. Inst. Min. Eng., XXII., 171, 1893. Rec. C. Luedekingand LEAD AND ZINC. 247 were regarded as a nuisance ; of late years the zinc has been much more of an object than the lead. The deposits in south- west Virginia (Example 26) also produce lead, but are best known for zinc. 2.06.11. Example 26. Wythe County, Va. Residual de- posits or crusts of calamine and smithsonite, resting upon Lower Silurian (Ordovician), limestone or dolomite, and prob- ably derived from disseminated blende, during the weathering of the country rock. Deposits of blende are also known in the limestone. The ore- bearing terrane is exposed over a considera- ble extent of country, running from near Roanoke, one hundred miles westward. The largest mines are in Wythe County, and of these the Bertha is best known. The Bertha ores are cala- H. A. Wheeler, "Notes on Missouri Barite,'' Aiitei-. Jour. Sci., December, 1891, p. 495. R. W. Raymond, "Note on the Zinc Deposits of Southern Missouri," Trann Amur. Inst. Min. Eng., VIII., 105; Eng. and Min. Jonr., October 4, 1879. J. D. Robertson, " A New Variety of Zinc Sulphide from Cherokee County, Kansas," A.iner. Jour. Sci., iii., XL., p. 160. "Missouri Lead and Zinc Deposits," Ainer. Geol., April, 1893, 235. A. Schmidt and A. Leonhard, MisHOuri Geol. Survey, 1874. A. Schmidt, " Forms and Origin of the Lead and Zinc Deposits of Southwest Missouri," Tca/i.?. St. Louis Acad. Sci., III., 246; Anier. Jour. Sci., iii., X., p. 300. Die Bleiund Zinle Erzlagerstatten von Sildwest Missouri. Heidelberg, Germany, 1876. E. J. Schmitz, "Notes of a Reconnaissance from Springfield, Mo., into .Irkansas, '' Trans. Ainer. Inst. Min. Eng., February, 1898. W. H. Sea- men, "Zinciferous Clays of Southwest Missouri," Arner. Jour. Sci., iii., XXXIX,, p. 38. H. S. Wicks, "The Joplin Tii^tY^iA,," Engineering Mag- azine. Februarj', 1894. Artluir Winslow, "Notes on the JLead and Zinc Deposits of the Mississippi Valley and the Origin of the Ores," Jomc. of OeoL, I,, 612, 1893. Reo. "Lead and Zinc Deposits of Missouri," Trans. Amer. Inst. Min. Eng., XXIV,, 634 and 931. Rec. "Report on Lead and Zinc," Missouri Geol. Survey, VI. and VII., 1894. Rec. See also pamphlet on "Missouri at the World's Fair," 1893. "Historical Sketch of Lead and Zinc," Eng. and Min. Jour., November 17, 24, 1894; January 19, lS!)o. Kansas. — G. P. Grimsley, "Kansas Mineral Products," Eleventh Bien- nicd Report Kansas Board of Agriculture, 1897-98, 502. E. Haworth, "A Couti-ibution to the Geology of the Lead and Zinc Mining District of Cherokee County, Kan., Oskaloosa, la.," 1894, privately printed. R. Hay, "Geological and Mineral Resources of Kansas," Eighth Biennicd Report .State Board of Agriculture, 1891-92, 25. B. F. Mudge, Idem, 1878. O. St. John, Idem, 1881-82. See also J. D. Robertson, cited under Missouri. Arkansas. — E. J. Schmitz, "Notes of a Reconnaissance from Spring- field, Mo., into Arkansas," Trans. Amer. Inst. Min. Eng., February, 1898. A Report on Lead and Zinc in Arkansas is now in press with the State Geol. Survey (1899). 248 KEMP'S ORE DEPOSITS. mine acd smithsonite, both crystallized and earthy or ochreous. They lie upon a limestone which is of very irregular surface, be- ing so deeply pitted by superficial decay that it projects in knobs and pil- lars, and sinks in interven- ing depressions. These are shown very graphically in Figs. 82 and 83, where they are left in relief by the stripping. They are mantled and rounded off by the overlying residual clay, which may be 50 to 75 feet deep. The ore lies in crusts and chunks or as a powdery mass upon or "near the limestone in the clay, and is won either by stripping this, or by shafts and drifts. (See Fig. 80.) According to Boyd, in one section there are 486 feet of strata impi'egnated with zinc and lead sulphides, with some pyrite. At the Wythe Company's mines both the oxidized ores and the unchanged sulphides of zinc and lead in the underlying limestone are exploited, but at the Ber- tha mines there is practi- cally no lead, the product being a very pure spelter. More or less limonite is NIVlNnOM'fillVd ONIHVOB •AlO '0 'N ■« 'a 'M V 'H U3Am M3N « Nivj.Nnon tiadvuo ■a -a *« » 'N i > K M -^_ 5 « fl o I" S , 5 . ? i. = !r g ! WB OOJODr^tDin-^cooi • ■as s a .5- K) t I 6 'MVOO VNOOi'lV Fig. 83. — View of open cut in the Bertha Zinc Mines, Va. photograph by J. F. Kemp, 1895. From a FiGh 83. — View of open cut in the Wythe Zinc Mines, Va. photograph by J. F. Kemp, 1895. From a LEAD AND ZINC. 249 obtained from all these surface workings, and is sent to neigh- boring blast furnaces. Near Bonsacks the gossan of the ore was exposed, but not recognized for a longtime, in a cut of the Norfolk and Western R. R. The mine yielded rich earthy oxidized ores, which, how- ever, passed in depth into a very intimate and rebellious mix- ture of zinc-blende and pyrite. These deposits extend over a wide stretch of country, running from near Roanoke, one hundred miles westward.' Related deposits occur in eastern Tennessee, and have fur- nished more or less ore, chiefly calamine. They are not large as a rule.^ They occur in the Knox dolomite, at the base of the Lower Silurian, and favor its contact with the underlying Cambrian Conasauga shale^ in the area of the Cleveland folio cited below. 2.06.12. Blende is a frequent associate of galena in the Rocky Mountains, but it has been only recentl}' worked for any zinc product, and then largely as a by-product in extract- ing silver. (See 2.07.10.) ' C. R. Boyd, "Resources o" Southwest Virginia," p. 71. "Mineral Wealth of Southwest Virginia," Trans. Amer. Inst. Min. Eng., V., 81; Jbid, VIII., 340. " The Wythe Lead and Zinc Mines, Va.," Eng. and Min. Jour., June 17 and 24, 1893. W. H. Case, "The Bertha Zinc Mines at Bertha, Va.," Trans. Amer. Inst. Min. Eng., Vol. XXII., p. 511, August, 1893. H. Credner, Zeitsch. fur die gesamrnten Naturwissenschaften, 1870, XXXIV.,' p. 24. F. P. Dewey, "Note on the Falling Cliff Zinc Mine (Bertha Company)," Trans. Amer. Inst. Min. Eng., X., 111. A. v. Groddeck, Typus Austin. Lehre von den Lagerstattt'u der Erze, p. 103. ' J. M. Safford, Geology of Tennessee, p. 482. W. H. Gildersleeve, "Zinc Ores in Tennessee," TJnixtersity Scientific Magazine, August, 1896 Quoted by the Eng. and Min. Jour., September 18, 1897, 386. ' Cleveland Folio, by C. W. Hayes. U. S. Geol. Survey, Morristo^M:i Folio. Arthur Keith, Idem, CHAPTER VII. ZINC ALONE, OR WITH METALS OTHER THAN LEAD. 2.07.01. Zinc commonly occurs in association with lead, but there are one or two exceptional deposits in this country which are without lead, and which have no parallel in other parts of the world. The minerals containing zinc at Franklin Furnace and Ogdensburg, N. J., are known elsewhere only as rarities, although they are found in vast amounts in New Jersey.^ ZINC SERIES. Zn. 8. Fe. SiO^, Mn. Sphalerite (oommonly call blende) ZnS 67 33 Zineite, ZnO 80.3 FrankHnite, (Fe.Zn.Mn)0(Fe.Mn)203 (variable) 5. .54.. .01.8 ... T.-o Willemite, 2ZiiO.Si02 58. .5 27.0 ... Calamine, aZnO.SiO^, H^O .54.2 .. .. 2.5.0 ... Smithsonite, ZnO.COa 52.0 2.07.02. Example 27. Saucon Valley, Pennsylvania. Zinc-blende and its oxidation products, calamine and smith- sonite, filling innumerable cracks and fissures in a disturbed, magnesian limestone, thought to belong to the Chazy stage. The ore bodies occur in the Saucon Valley near the town of Friedensville, about four miles south of Bethlehem. The lime- stone is inclosed between two northerly spurs of the South Mountain, and has apparently been tilted and shattered by the upheaval of the latter. The shattering and disturbances decrease as the South Mountain is left and the dip decreases. There are three principal mines, the Ueberroth, the Hartman, and the Saucon, the first named being in the portion which is ' F L. Clerc, "Zinc in the United States," ilfmerai Resources, 1882, p. 358. W. R. Ingalls, " The Nomenclature of Zinc Ores," Trans. Amer. Inst, ilin. Eng., XXV., 17 and 955, 1895. ZINC ALONE. 251 tilted nearly to a vertical dip, and is much disturbed, while the next is where the dip has gradually decreased to 35°. The mines are on a belt some three-quarters of a mile long. At the Ueberroth an enormous quantity of calamine was found on the surface, but it passed in depth into blende and was clearly an oxidation product. In the others the blende came nearer the surface. The ore follows the bedding planes, and the joints normal to these throughout a zone varying from 10 to 40 feet across, and fills the cracks. At their intersection the largest masses are found. Six larger parallel fissures were especially marked at the Ueberroth. This mine proved in development to be very wet, and a famous pumping engine, the largest of its day, was built to keep it dry. The Hartman and Saucon are less wet. A little pyrite occurs with the blende, and thin, powdery coatings of greenockite sometimes appear on its sur- face, but it is entirely free from lead and a very high grade of spelter is made from it. The mines were strong producers from 1863 to 1876, but little has been done since, although it has been reported that the great pumping engine might again start, and the mines may once more furnish considerable quantities of ore. 2.07.03. The veins were evidently filled by circulations from below that brought the zinc ore to its present resting place in the shattered and broken belt. Drinker considers it to have been derived from a disseminated condition in the limestone.^ 3.07.04. Example 2S. Franklin Furnace and Sterling, N. J. Bed veins consisting of franklinite, willemite, zincite, etc., in crystalline limestone, in many respects analogous to the magnetite of Example 13. The franklinite and zincite bedded deposits are in a belt of white, crystalline limestone which runs southwesterly from Orange County, New York, across north- western New Jersey. It was considered metamorphosed Lower Silurian by H. D. Rogers, but its association with Archean gneiss is so intimate and involved that others have regarded it as likewise Archean. Blue Siluro-Cambrian limestone and • F. L. Clerc, Mineral Resources, 1882, 361. Reo. H. 8. Drinker, "On the Mines and Works of the Lehigh Zinc Company," Trans. Amer. Inst. Min. Eng., I., 67. C. E. Hall, in Rep. D3, Second Qeol Survey, Penn., p. 339. IXe Gfruben und Werke der Lehigh Zink Qesellschaft in Pennsyl- vanien, B. und H. Zeit., 1872, p. 51. a52 KEMP'S ORE DEPOSITS. quaitzite are also near. F. L. Nason has recently supported the Cambro-Silurian age of the white limestone, on the ground that the white and the blue varieties are inextricably involved, and that many intrusions of granite are present, which would account for the metamorphism of the latter. In one of the smaller areas of blue that was in the midst of the white, some fossils of the Olenellus fauna were discovered. J. E. Wolff and others in association with him have referred the white limestone to the Archean rocks, and have agreed that the blue was either mixed with it because of faults or because the quartzite had filled cavities in the former during the advance of the Cambrian sediments across the Archean rocks. Of the presence, however, of granites and other intrusions in the white limestone there is no doubt, but they are tbought by Wolff to be pre-Cambrian, and probably to.be later than the ore. In limestones and ore at once so mashed and so old the relations BUCKWHEAT Fig. M.— Gross section at Franklin Furnace, N. J., corresponding to AA. of map (Fig. 88), and four times the scale of map. At the left is blue limestone and quartzite. After J. F. Kemp, Trans. N. T. Acad, of Sciences, XIIL, 86, 1893. are obscure. At Franklin Furnace the crystalline limestone forms a low hill (Mine Hill) east of the upper waters of the Wallkill, and again at Ogdensburg, two miles south, another (Sterling Hill), on the west bank. There is a valley and unex- posed strip between, so that the unbroken continuity without a possible intervening fault cannot be established. The bed at Franklin outcrops on the west side of the hill. It begins on the north just across the Hamburg road, and runs south 30° west as a continuous bed for about 2,500 feet. This portion is called the Front vein. It contains on the north the old Ham- burg mine, then the Trotter mine, and in the southern portion belongs to the New Jersey Zinc and Iron Company. It runs from 8 to 30 feet broad at the outcrop, but swells below. It dips southeast 40 to 60° into the hill, and is interbedded in the jiraestone. In the Trotter mine a wedge or horse of hornblende. Fig. 85.— View of the west vein at Franklin Furnace looking south. The two shafts are at the Trotter Mine. Photograph^ by J. F. Kemp, 1893. Fig. 86. — View of open-cut at south end of Mine Hill, Franklin Furnace, N. J. , exposing the syncline of ore. From a photograph by J. F. Kemp, February 34, 1899. Fig. 87. — View of Stirling Hill, Ogdensburgh, N. J., looking southwest from the N. Y., S. and W. R. R. embankment. The mines are at the foot of the hill. From a photograph by J. F. Kemp, 1893. ZING ALONE. 253 augite, plagioclase, and various other silicates enters the bed a short distance. In this horse some of the most interesting minerals have been found, such as fluorite, rhodonite, blende (var. cleiophane), smaltite (var. cholanthite ), axinite, etc. At the end of the Front vein — or, more properly, bed— a branch or bend strikes off at an angle of 30 to 40° to the east. This more easterly branch, which is called the Bucjjwheat mine, outcrops on the surface some 500 feet, and then, after being cut by a trap dike 32 feet wide, pitches down at an angle of 27° and passes under the limestone. The portion of the mine northeast of the dike furnishes the most and best ore. The surface out- crop of the Buckwheat was 25 to 30 feet across, but it swelled below to 52 feet, and in the second level, about 200 feet from the surface, it was penetrated by a cross-cut 125 feet without finding the wall. The character of the ore varies; for, while it is excellent at the point of the cross-cut, at 125 feet nearer the intersection with the front bed it becomes lean, while pre- serving its width lower. Beyond the dike the bed is likewise broad, and is mined out for 40 to 50 feet across. The workings are now some distance down on the pitch. The impression made by the arch of the roof and by the curving beds is that this is the crest of an anticline whose axis pitches north 27°, and whose central portion is formed by the franklinite bed being doubled up together on itself before the two parts diverge in depth. Its western portion probably is continuous in a syncli- nal trough with the front bed, and its eastern portion dips east at some unknown angle. It may, however, be merely a bulg- ing termination of the bed and the results of deeper mining will be awaited with interest. About 1890 deep drilling was instituted along the strike of the Buckwheat ore, and about one-third of a mile distant from it. The holes caught the ore at approximately 1,000 feet down, and H large shaft was at once installed which has since proved extremely productive. The workings have shown that the prolongation of the Buckwheat ore body flattens notably at this portion, and rounds out along the strike in a sort of spoon-bowl termination. To express the exact shape in this portion the stereogram Fig. 90 should be somewhat modified, still it illus trates the general shape fairly well. Apparently the ore is cut off by a fault to the northeast, but the relations are not yet 254 KEMP'S ORE DEPOSITS. fully demonstrated. The whole southern portion of the ore body, as far as the trap dike, is now being stripped of limestone preparatory to open-cut mining, and the geological relations are beautifully displayed. 3.07.05. The ore consists of franklinite in black crystals, usually rounded and irregulai', but at times affording a quite perfect octahedron combined with the rhombic dodecahedron and set in a matrix of zincite, willemite and calcite. The rich- est ore lacks the calcite and consists of the other three in vary- ing proportions. The best ore is in largest amount in the Buckwheat mine, beyond the trap dike which cuts it. The limestone containing the ore has a notable percentage of man- ganese replacing the calcium, and where it is exposed to the atmosphere it weathers a characteristic brown. An analysis of a sample occurring with the ore at Sterling Hill afforded F. C. VanDyck: CaCOj 80.33 MnCOa 16.57 FejiOa 0.50 SiOg 0.20 H5O 1,00 100.50 The percentage of manganese' is very high for a limestone. 2.07.06. The Sterling Hill outcrop is less extensive. It be- gins on the north with the New Jersey Zinc and Iron Com- pany's property, and runs south 30° west for 1,100 feet. It then branches or bends around to the west and runs north 60° west for 30 feet, bending again to north 30° east, and pitches beneath the surface. Thus the general relations between the front and back beds are somewhat the same as at Mine Hill, and the dip and pitch are similar. The principal workings are on the Front vein, where there are two veins (beds), ac- cording to the older descriptions, one rich in franklinite and the other in zincite. It is doubtful if there really are two dis- tinct beds, but probably one portion is richer in zincite than the other. The part mined is from two to ten feet. The foot- wall is corrugated and causes many pinches and swells, whose troughs pitch north. The limestone between the front and back outcrop is charged with franklinite and various silicates ZINC ALONE. 256 (jeffersonite, augite, garnets, etc.), and has been mined out in large open cuts now abandoned. A deposit of calamine was found in the interval about 1876, and has furnished many fine museum specimens. 2.07.07. It is not clear that the Sterling Hill and Mine Hill deposits were once continuous. The bed at Mine Hill runs in the front portion close to the contact of the white limestone and the gneiss. The Sterling Hill bed is much farther away from the gneiss, and this would indicate that it is at a higher horizon. The evidence, too, of a pitching syncline is strong, but a pitching S-fold is not as clear. A faulting of the Arche- an rocks in an east and west line across their strike, and a sub- sequent tilting so as to give them a northerly pitch, is a very Figures 88 and 89. — Qenlogical maps of Mine Hill and Sterling Hill, showiny the relations oj the ore-bodies. After J. F. Kemp, Trans. N. Y. Acad, of Sciences, XIII., pp 81 and 85, 1893, widespread phenomenon in the Highlands, and lends weight in this instance to the idea that a fault intervenes between the two hills. 2.07.08. The origin of these beds is very obscure. They are so imique in their mineralogical composition that very lit- tle direct aid is furnished by deposits elsewhere. At Mine Hill, below the franklinite bed a bed of magnetite was early discovered, and was mined for iron. It has since been met in the drill cores from the deep shaft of the northeast, and is therefore remarkably persistent beneath the zinc ore. There are many points of analogy between the franklinite beds and extended magnetite deposits. They are both minerals of the 256 KEMP'S ORE DEPOSITS. spinel group, and tbe spinels are a common result of raetamor- phic action. The presence of zincite and willemite complicates matters, however, and while an original ferruginous deposit' might he conceived with a large percentage of manganese, such abundance of zinc is beyond previous experience. It is. however, suggestive that no inconsiderable amount of zinc is found in the Low Moor (Va.) limonites, as shown by the flue dust (see E. C. Means, "The Dust of the Furnaces at Low Moor, Va.," Buffalo meeting, Amer. Inst. Min. Eng., XVIL, p. 179), and this in the course of a protracted blast may amount to many tons, but it does not approach the Franklin Furnace ores. None the less, in the absence of a better explanation, the franklinite bed may be thought of as perhaps an original man- FlGlTEES 90 and 91. — Stereograms of the ore bodies at Mine Hill and Sterling Hill. After J. F. Kemp. Trans. N. Y. Assoc. of Sciences, XIII. , pp. 83 and 89, 1893. ganese, zinc, iron deposit in limestone, much as many Siluro- Cambrian limonite beds are seen to-day, and that in the gen- eral metamorphism of the region it became changed to its pres- ent condition. Minerals of the spinel group occur all through this limestone belt, and in Orange County, New York, to the north, there is an old and prolific source of them. 2.07.09. As has been earlier stated, granite intrusions are common in the white limestones adjacent to or near the ore, and unless these are proved to be of later age than the ore, they may have been an important factor in the ore formation. It is very reasonable that the igneous intrusion should start ore- bearing currents along a certain stratum in the limestone, which would replace it with ore. Subsequent folding and ZINC ALONE. -Ibl metamorphism must then have changed these ores, whatever they were, to the present unupual minerals. This view of the method of origin has been advocated by J. F. Kemp in the paper cited below, and more careful search, as well as the sinking of the new shaft on the strike of the back vein at Mine Hill, have served to bring to light more intrusions of granite than were previously known. Chon- drodite, fluorite and other contact minerals occur near them. Nason has also shown by an interesting series of analyses that the limestone next the granites tends to be pure CaCOs, shading gradually at a distance to dolomitic varieties. Victor Mon- heim, in discussing the vein of willemite worked in the forties at Stolberg, near Aachen, has urged that at temperatures suffi- ciently high the anhydrous silicate of zinc may separate di- rectly from the solutions, while at lower temperatures the hj'drous salt results. His experiments and conclusions give support to the view that the igneous, pJutonic intrusions have played an important role in the ore deposition. (See V. Mon- heim, Verli. d. Naturhist Ver. der preus. Rheinlaiide u.. Westphalen, V., 162, 1848 ; VI., 1, 1840.) Were this true we would not be compelled to assume an original bed of blende from which these oxidized compounds have been derived. It is a general experience, however, that hj'drated oxidized ores of zinc have passed in depth into blende, and this fact, in con- nection with the almost entire absence of blende in these mines, adds to their puzzling character. Were they, however, at one time a thoroughly oxidized gossan containing the three metals specially prominent, the intrusions of granite are probably responsible for the change to their present combinations.^ ' F. Alger, "On the Zinc Mines of Franklin, Sussex Co., 11. S." Amer. Jour. Set., l, XL VIII., 252, 1845. Rec. J. Beco, De I'Etat actual, des Industries du Zinc, etc., aux Etats Unis d'Amerique, Revue Universelle des Mines, 1877, II., 129. W. P. Blake, in paper on "Zinc Ore Deposits of Southwestern New Mexico,'' Trans. Amer. Inst. Mm. Eng., XXIV., 187, 1894, gives notes on the " New Jersey Ore Bodies. " N. L. Britton, Ann. Rep. of the State Oeologist, N. J., 1886, p. 89. An excellent cross-section of Mine Hill is given. G. H. Cook, " On the Probable Age of the White Limestone at the Sussex and Franklin Zinc Mines," Amer. Jour. Sci., ii., XXXII., 208, Geol. of New Jersey, 669, 1868, with map. Rec. H. Cred- aer, "On the Franklinite Beds," Berg-tt. Hutt. Zeitung, 1866, 29; 1871, 369. Rec. E. F. Durre, ' ' Metallurgische Notizen aus New Jersey und 258 KEMRS ORE DEPOSITS. 2.07.10. Blende is known in nximerous places in the Rockj' Mountains, and is often argentiferous. When mixed with lead silver ores it has generallj' proved a drawback, and has raised the smelting charges. Eecently works have been erected at Canon City, Col., for the treatment of such ores, and very considerable quantities of blende are there turned into zinc- white. While the local demand for this pigment is not so heavy in the West as in the East, any process which frees the dem Lehigh Thai," Zeitsch. des Vereins deutscher Ingenieure, 1894, p. 184. B. K. Emerson, "On the Dykes of Micaceous Diabase, Penetrating the Bed of Zinc Ore at Franklin Furnace, Sussex Co , N. J.," Amer. Jour. Sei., May, 1883, 376. Aug. F. Foerste, "New Fossil Localities in the Early Paleozoics of Pennsylvania, New Jersey and Vermont,'' etc., Amer. Jour. Sci., iii., XL VI., 345. Discusses the local stratigraphy with a map. P. Groth, "Die Zinkerzlagerstatten von New Jersey," Zeitschrift fur Prak- tische Oeologie, May, 1894, p. 230. W. H. Keating and L. Vanuxem, "Geology and Mineralogy of Franklin in Sussex County, N. J.," Jour. Phila. Acad. Nat. Scl, 11, 277, 1822. Rec. J. F. Kemp, "The Ore Deposits at Franklin Furnace and Ogdensburgh, N. J.," Trans. N. Y. Acad. Sci., XIII., 76-98, 1893; gives a full bibliography and annotated list of minerals. Rec. F. L. Nason, Ann. Rep. State Oeol, N. J., 1890, p. 25; Amer. Oeol, VII., 241; VIII., 166; XII., 154. Amer. Jour. Sci., iii., XXXIX., 407, 1890. "The Franklinite Deposits of Mine Hill, Sussex County, N. J.," Trans. Amer. Inst. Min. Eng., February, 1894; Eng. and Min. Jour., May 3, 1894, p. 197. Rec. "Chemical Composition of Some of the White Limestone in Sussex Co., N. J.," Amer. Oeol., March, 1894, p. 154. T. Nuttall, ' ' Geological and Mineralogical Remarks on the Min- erals of Paterson and on the Valley of Sparta," N. Y. Med. and Phys. Jour., April, May and June, 1823. Amer. Jour. Sol, i., V., 239, 1833. Jos . 0. Piatt, Jr. , " The Franklinite and Zinc Litigation Concerning the Deposits of Mine Hill at Franklin Furnace, Sussex Co., N, J.," Trans. Amer. Inst. Min. Eng., V., 580, 1876-77. H. D. Rogers, "Geology of New Jer- sey, 1849, pp. 63-71, with a list of Minerals by Dr. S . Fowler. " Rec. G. C. Stone, "Analyses of Franklinite and Some Associated Minerals (two analyses of Zincite, four of Franklinite, five of "Willemite, one of Teph- roite)," School of Mines Quarterly, VIII., 148, 1887. G. Troost, "Observa- tions on the Zinc Ores of Franklin and Sterling, Sussex Co., N. J.," Jour. Phil. Acad. Nat. Sci., IV., 320, 1824. J. P. Wetherell, "The Mine Hill Ore Deposits in New Jersey and the Wetherell Concentrating Plant," Eng. and Min. Jour., July 17, 1897. J. D. Whitney, " Metallic Wealth of the United States," p. 348, 1854. J. E. Wolff and A. H. Brooks, "The Age of the Franklin White Limestone of Sussex Co., N. J.," XVIIl., Ann. Rep. Dir. U. 8. Oeol. Survey, Part II., pp. 425-457, 1899. J. E. WoM, "Oc- currence of Native Copper at Franklin Furnace, N. J.," Proc. Amer. Acad. Arts and Sci., XXXIII., 439, 1898, " Hardystonite, a new Calcium-zinc Silicate from Franklin Furnace, N. J.," Proc. Amer. Acad. Arts and Sci., XXXIV., 479. ZINC ALONE. 259 lead-silver or copper-silver ores of the objectionable zinc will operate favorably on many mines no\v handicapped. This has already proved to be the casev?ith the refractory sulphides met in depth at Leadville. Deposits of oxidized ores in southwestern New Mexico, near the town of Hanover, have recently been mined to a notable extent. The smithsonite and calamine as well as the blende, which is met in the same vicinity, are unmixed with galena, but the blende often contains intermingled pyrites. The ores occupy irregular caverns and seams in Paleozoic or Archean limestone, in close geological association with intrusive granite, contact zones and iron ores. A lenticular shape is often notable in the masses of blende. As remarked by Blake, the deposits show some interesting points of resemblance to those of New Jersey. The richest carbonates and calamine have been shipped to the East, but with the unavoidably high freights only the purest and best surface ores are available. (W. P. Blake, "Zinc-ore Deposits of Southwestern New Mexico," Trans. Amer. Inst. Min. Eng., XXIV., 187.) Large deposits of hematite and mag- netite have been worked to some extent in the same region, as a flux for lead-silver smelters, but their remoteness militates against their use as an iron ore. 2.07.11. A large amount of zinc ore is turned directly into zinc white and employed as a pigment. For this reason the statistics of the metal do not indicate all the ore mined. The accompanying figures are short tons. For detailed statistics see the annual volumes on "Mineral Industry" of the Engineer- ing and Mining Journal, 1894, and the"" Annual Heports of the U. S. Geological Survey. 1882. 1890, 1897. lUinois and Indiana 18,301 26,243 38,680 Kansas 7,366 15,199 33,895 Missouri 2,500 13,127 18,413 Eastern and Southern States 5,698 9,114 9,900 33,765 63,683 100,387 The amounts for 1883 and 1890 are from the Mineral Re- sources of the United States, 1889-90. p. ,89, those for 1897 are from the Mineral Industry, VI., 661. The statistics give the metallurgical output for the several States, not the mining. Indiana has no zinc mines. CHAPTER VIII. LEAD AND SILVER. 2.08.01. There are two general methods of extracting silver from its ores, the one indirectly, by smelting with and for lead ; the other by amalgamation, chlorination, or some such process. Hence under silver there are two classes of mines^ — -lead-silver and high-grade silver ores. Both have almost always vary- ing amounts of gold. The lead-silver mines furnish also, as noted above, by far the greater portion of the lead produced in the United States. Ores adapted to lead-silver metallurgical treatment form, in general, the oxidized alteration products of the upper parts (above permanent water level) of deposits of galena and pyrites. They may be well-marked fissure veins, chimneys, chambers, or contact deposits. Ores which of them- selves are adapted to other processes are often worked in with the lead ores, and unchanged sulphides are artificially oxi- dized by roasting preparatory to smelting. The localities are taken up geographically from east to west. 3.08.03. Lead-Silver Deposits in the Rocky Moun- tain Region and the Black Hills. — The mines are de- scribed in order from south to north, beginning with New Mexico. new MEXICO. 3.08.03. Example 39. The Kelley Lode. Oxidized lead ores, with some blende, calamine, etc., forming a contact de- posit betwe™ slates and porphyry. The ore body is in the Magdalena Mountains, thirty miles west of Socorro, and has supplied the Billings smelter at that point. Numerous other ore bodies along the contact between sedimentary and eruptive rocks occur in the same region. 3.08.04. Lake Valley. Farther south in Dona Ana County LEAD AND SILVER. 361 the mines of Lake Valley are and have been worked upon deposits very closely analogous to those of Leadville, which furnish the principal type. They contain less lead, hardly enough, in fact, to be classed as lead -silver ores, according to the recent valuable paper of Ellis Clark, although earlier descriptions place greater emphasis on the presence of carbon- ates of this metal. According to Clark, the geological section involved includes quartzite and limestone, considered Silurian, 600 feet; Lower Carboniferous, black shale, 100 feet; green shale, 60 feet; nodular limestone, 48 feet; blue limestone, 24 feet; crinoidal limestone, 125 feet, and overlying limestone, 50 feet; about 1,000 feet in all. These are penetrated by four distinct eruptions of igneous rocks, hornblende-andesite, rhyo- lite, obsidian and porphyrite. The obsidian is comparatively Fig. 92. — Qeological cross section at Lake Valley, New Mexico, to show the relations of the ore. The black mass is ore ; the dark hachures in the lower left-hand corner are black shale. After Ellis Clark, Trans. Amer. Inst. Min. Eng., XXIV., p. 155. unimportant, and of the others the porphyrite is most inti- mately associated with the ore. The ore bodies are always connected with the blue limestone, and lie along the contact of this, either with the porphyrite or the overlying crinoidal limestone. They are in the nature of large chutes or elongated contact deposits, very similar, as the figure will indicate, to those at Leadville. The ores are of several varieties but the general components, in addition to the silver, are silica, oxides of iron and manga- nese, limestone, some galena at times, and some zinc. The varying percentages of the silica and bases afford basic, neutral and siliceous ores. In the bonanza called the Bridal Chamber, great masses of horn-silver were found. Many 263 KEMP'S OBE DEPOSITS. ores, and interesting metals, such as vanadinite, descloizite, etc., have made the district well known to collectors. Clark favors the view that the leaching of the porphyrite (which is argentifer- ous) during its exposure and erosion, by descending surface waters, has been the source of the ore. An earlier view attrib- uted it to uprising currents.' COLORADO. 2.08.05.' Example 30. Leadville. Bodies of oxidized lead- silver ores, passing in depth into sulphides, deposited in much faulted Carboniferous limestone, in connection with dikes and sheets of porphyry. Leadville is situated in a valley which is formed by the head waters of the Arkansas River. The valley runs north and south, being confined below by the closing in of the hills at the town of Granite. It is about twenty miles long and sixteen broad, and even to superficial observation is seen to be the dried bottom of a former lake. The mountains on the east form the Mosquito range, a part of the great Park range, while those on the west are the Sa watch, and constitute the Contiisen- tal Divide at this point. Leadville itself is on the easterly side, upon some foothills of the Mosquito range. The eastern slope of the Mosquito range rises quite gradually from the South Park to a general height of 1:3.000 feet. The range then forms a very abrupt crest, with steep slopes looking westward, which are due to a series of north and south faults whose east- erly sides have been heaved upward as much as 7,500 feet. The faults pass into anticlines along their strike. The Mosquito range consists of crystalline Archean rocks, foliated granites, gneisses, and amphibolites, and of over 5,000 feet of Paleozoic sediments and igneous rocks. The former include Cambrian quartzite, 150 to 200 feet; Silurian white limestone, 160 feet, and quartzite, 40 feet; Carboniferous blue limestone, 200 feet (the chief ore-bearing stratum) ; Weber shales and sandstones, 2,000 feet; and Upper Carboniferous limestones, 1,000 to 1,500 feet. The igneous rocks are generally porphyries. The sedi- mentary rocks were laid down in Paleozoic time on the shores ' E. Clark, "The Silver Mines of Lake Valley. N. M.," Trans. Amer. Inst. Min. Eng., XXIV., 138, 1894. Rep. of Director of the Mint, 1883, Lake Valley, p. 341 ; Kelley Lode, p. 37(5. B. Sillimaii, ' ' Mineral Eegions of New Mexico," Trann. Amer. Inst. Min. Eng.. X., 234. LKAD AND SILVKU. 263 of the Archean Sawatch Island, and were penetrated by the igneous rocks, probably at the close of the Cretaceous. They were all upheaved, folded, and faulted in the general elevation of the Rocky Mountains, about the beginning of the Tertiary period. The intrusion of the igneous rocks was the prime mover in starting ore deposition, and the solutions favored the under sides of the sheets, along their contacts with the blue Carboniferous limestone. 2.08.06. The early history of Leadville will be subsequently referred to in speaking of auriferous gravels. The lead-silver ores first became prominent in 1877, although discovered in 1874, and bj' 1880 the development was enormous. The region grew at once to be the largest single producer of these ores, and has remained such ever since. The mines are situated east of the city on the three low hills. Fryer, Carbonate and Iron, but recently a deep shaft in the city itself has found the extension of the ore chutes and opened up great future supplies. The ores have chiefly come in the past from the upper oxidized por- tions of the deposits. Of late years, however, the older and deeper workings have been showing the unchanged sulphurets. The ores are chiefly earthy carbonate of lead, with chloride of silver, in a clayey or siliceous mass of hydrated oxides of iron and manganese. In the Robert E. Lee mine silver chloride occurred without lead. Some zinc is also found, and a long list of rare minerals. Where the ore is in a hard, siliceous, limonite gangue it is called hard carbonate, but where it is sandy and incoherent it forms a soft carbonate, or sand carbon- ate. All the older mines produce small amounts of gold, but in some newer developments the gold is of more importance than the silver. A few ore bodies are found at other horizons than the Carboniferous. They also run in instances as much as 100 feet from the contact, and may likewise be found in the porphyry, doubtless replacing included limestone. They were all deposited as sulphides, and, according to Emmons, when the rocks were at least 10,000 feet below the surface. In 1891 and 1892 great interest centered in the discovery and development of ore bodies, whose values in gold much ex- ceeded those in silver, and which were situated further east from the city of Leadville than the older silver mines. The gold output has now proved very considerable, although lim- LEAD AND BILVER. 305 ited to but few mines. The geological associations are much the same as in the older workings, and indeed the gold ores occur on the extended lines of the older chutes, when projected to the eastward. 2.08.07. In the valuable monograph on the region, which is now a classic on the subject, and which is cited below, Em- mons endeavors to prove the following points : I. That the ores were deposited from aqueous solution. II. That they were originally deposited mainly in the form of sulphides. III. That the process of deposition involved a metasomatic interchange with the material of the rock in which thej' were deposited. IV. That the mineral solutions or ore currents were concen- trated along natural water channels, and followed, by prefer- ence, the bedding planes at a certain geological horizon, but that they also penetrated the adjoining rocks through cross joints and cleavage cracks. These additional points are also advanced : I. That the solutions came from above. II. That they were derived mainly from the neighboring eruptive rocks. 2.08.08. The first four points are doubtless correct, and No. III. is an important application of the theory of replacement, frequently referred to in the introduction. The last two propo- sitions merit less confidence. Seven additional years of mining have brought many new facts to light, and have led others (A. A. Blow in particular, whose valuable paper is cited below) to refer the ores to upward rising currents. Emmons foresaw this possibility and mentioned it on p. 584 of his mono- graph. The amount of the adjacent, igneous rocks is quite insufficient to afford the ore. In alteration the galena has passed through an intermediate s1;age of sulphate before chang- ing to carbonate. These mines have been important not alone in their own metallic products, but in furnishing the smelters with oxidized lead ores, they have supplied a means of reduc- tion for many other more refractory ones, which could be con- veniently beneficiated through the medium of lead.' Much copper occurs with the sulphides now met in depth. ' F. M. Amelung, "The Geology of the Leadville Ore District," Eng. 266 KEMP'li ORE DEl'OSITS. 2.08.09. Example 30a. Ten Mile, Summit County. Bod^ ies of argentiferous galena, pyrite, blende and their oxidized products replacing or impregnating beds of Upper Carbonifer- ous limestone, or filling fissure veins. The geological section at Ten Mile resembles that of Leadville, which lies 15-20 miles south, but the productive strata are in the Upper Carbonifer- ous or Maroon formation, instead of in the Lower Carboniferous or Leadville limestone. The Maroon formation is chiefly sandstones. It is estimated at 1,500 feet thick, and is separated from the Leadville blue limestone by 300 feet of Weber grits. It contains several thin beds of limestones in connection with which some of the ores are found. The ore bodies present at least two types. The first is illustrated by the Robinson mine, E'ig. 94, in which the ore lies along two small faults and replaces the limestone between and on either side of them. In this as in the other mines the chief mineral in the unoxidized por- tion is pyrite, or marcasite or pyrrhqtite. With one or the other of these are smaller amounts of galena and blende. The oxi- dized portions proved the richest, the others require concen- tration. The fissure vein type is illustrated by the Queen of the West mine, whose ores were found in several parallel fault and Min. Jour., April 16, 1880, p. 25. " On the Origin of the Ore," Ibid., December 30, 1879. A. A. Blow, " The Geology and Ore Deposits of Iron Hill, Leadville, Colo.," Trans. Amer. Inst. Min. Eng., XVIII., 145, 1889. Rec-. Ann. Rep. Colo. School of Mines, 1887, p. 62. "The Leadville Gold Belt," Eng. and Min. Jour., January 36, 1895. Rec. Maps. S. F. Emmons, "Geology and Mining Industry of Leadville," Monograph 1 J, U. S. Geol. Survey. Eec. Second Ann. Rep. Director of V. S. Oeol. Sur vey. Ret;. Tenth Census, Vol. Xlil., p. IG. F. T. Freeland, "The Sul- phide Deposits of South Iron Hill, Leadville," 2''rans. Amer. Inst. Min. Eng., XIV., 181. C. Henrich, "The Character of the Leadville Ore Deposits," jEng. and Min. Jour., December 27, 1879, p. 470. "Origin of the. Leadville Deposits," Etig. and Min. Jour., May 12, 1888. p. 43. "On the EveiiingStar Mine," Ibid., May 7, 1881, p. 361. "Leadville Geology," Ibid., June 3 and 10, 1883; "Historical," May 30, April 6, 13, 30, 27, 1878; also many other allusions, 1879-81. R. W. Raymond, "Report on the Little Pittsburg Mine," Eng. and Min. Jour., June 38, 1879. L. D, Ricketts, "The Ores of Leadville," Princeton, 1883. C. M. Rolker, "Notes on Leadville Ore Deposits," Trans. Amer. Inst. Min. Eng., XIV., 373, 949. F. L. Vinton, " Leadville and the Iron Mine," Eng. and Min. Jour., Feb- mary. 15, 1879, p. 110; also June 28, p. 45. A series of shoi't paper.« on ' ' The Gold Belt " was published in 1894, by the Leadville Chamber of Commerce. LEAD AND SILVER. 267 fissures, as shown in Fig. 95. The ores were rich in the oxi- dized zone, but grew lean in the sulphides. In the White Quail type the ores are somewhat less definitely eircumscribed. They still form elongated replacements, but contain consider- TV Fig. 94. — Section through the No. 2 ore-chute of the Robinson mine. Ten-mile district, Colo. After 8. F. Emmons, Ten-mile Special Folio, U. S. Geological Survey. Fig, 95. — Cross-section, Queen of the West mine, Ten-mile district, Goto. Ihe rich ore appears in the darker vertical bands. After S. F. Emmons, Ten-mile Special Folio, U. 8. Geological Survey.' able quartz, calcite and barite. They shade out laterally into jasperoid quartz, which is succeeded by barren limestone. The amount of sulphides is enormous.' ' S. F. Emmons, Tenth Census. Vol. XIII., p. 73. Ten Mile Special Folio, 1899. Rec. The above description has been chiefly drawn from this folio. 368 KEMP'S ORE DEPOSITS. 2.08.10. Example 306. Monarch district, Chaffee County. Oxidized lead-silver ores in limestone. The belt of limestones south from Leadville contains some notable ore bodies in Chaf- fee County. The Monarch district is the most important. It is situated at the head waters of a branch of the South Arkan- sas River. The ore lies in limestones whose age is not yet accu- rately determined. The Madonna mine is the best known and has shipped much ore to Pueblo.^ 3.08.11. Example 30c. Eagle River, Eagle County. Galena and its alteration product, anglesite, in Carboniferous lime- stone, on the contact between it and quartzite or porphyry. The mines lie in the valley of Eagle River, on, the western slope of the Continental Divide. The galena has changed to the sulphate, instead of carbonate, probably having been less completely oxidized than at Leadville, and marking the inter- mediate stage in the process. The wall rocks lie quite undis- turbed, having a low dip of 15° north, and not being faulted. Lying lower than the lead-silver deposits, and in Cambrian quartzite, on the contact with an overlying sandstone, are found chutes carrying gold in talcose clay.^ 3.08.13. Example 30d. Aspen, Pitkin County. Bodies of lead-silver ores, largelj'' oxidized, occurring with much barite, chiefly at the intersections of a series of vertical cross-faults, with two bed faults in Carboniferous limestone and dolomite; but also in less important amounts, although in similar rela- tions to faults, in strata both older and later. Aspen is on the western slope of the Continental Divide, in the valley of the Roaring Fork, just at the point, where it crosses the contact of crystalline Archean gneisses and Paleozoic sediments. The stream cuts them at right angles to the strike. Aspen Moun- tain lies on the south side, and Smuggler Mountain on the ' S. F. Emmons, Tenth Census, Vol. XIII., p. 79. Rep. Director of the Mint. 1884, p. 181. ° S. F. Emmons, "Notes on some Colorado Ore Deposits," Colo. Sci. Soc. Vol. II., Part II., p. 100. E. E. Oloott, "Battle Mountain Mining District, Eagle County, Colorado," Eng. and Min. Jour., June 11, 1887, pp. 417, 435; i6iU, May 21, 1893, p. 545. G. C. Tilden, " Mining Notes from Eagle County," Ann. Rep. Colo. State School of Mines. 1886, p. 39. LEAD AND SILVER. 269 270 KEMP' 8 ORE DEPOSITS. north. The limestone belt continues north and south, and is prospected over a stretch of nearly forty miles. 3.08.13. The geological section at Aspen embraces the following strata, which have been carefully determined and measured by J. E. Spurr. Upon the Archean granite rests the Sawatch formation of the Cambrian, 300 to 400 feet thick. Beginning as a thin conglomerate, it passes into a quartzite and then into a sandy dolomite. The Yule formation of the Silurian is a dolomite, 3.50 to 400 feet in thickness. The Parting Fig. 97a. — Cross section of the Delia S. Mine, Smuggler Mountain. Aspen, Colo. After .T. E. Spurr, Monograph XXXI. U. S. Geological Survey, Plate XLII, b. Section through the Durant and Aspen Mines, by D. Rohlfing, Mem, Plate XL. The hlacTc is ore. Quartzite, Devonian, 60foet thick, lies above. The Carbonifer- ous has three members. The lowest is the Leadville limestone, of which 300 to 350 feet is a brown dolomite, and 100 to 150 feet a blue limestone, the two being separated bj'the "Contact" bed- fault. Above the Leadv-lle limestjne are the Weber shales and carbonaceous limestone, 1,000 feet or more; and the Maroon grits, 4,000 feet. The Mesozoic beds which rest on the last named are very thick, but have no important relation to the ore. LEAD AND SILVER. 271 2.08.14. Aside from the Archean granite there are two eruptive rocks in the district. A diorite-porphyry forms a sheet at and below the Parting Quartzite, and thickest at the south, but thinning to the north. A quartz-porphyry, very like the "White Porphyry" at Leadville (compare Pig. 93), is 400 feet thick on Aspen Mountain, but it thins out both to the north and the south. It appears near the base of the Weber shales. The age of both the porphyries is probably late Cretaceous. 2.08.15. After the deposition of the Laramie beds, of- the Cretaceous, a compressive force from the west developed an overturned anticline, which culminated in a great fault along Castle Creek, to the west of the mines. A syncline was pro- duced on the east limb of the great anticline, and was later domed upward by an uplift, which gave the trough a marked pitch to the north. During the folding two faults were produced parallel with the bedding of the Leadville limestone. One runs along at the contact of the dolomite and the blue limestone (the "Contact" fault) ; the other follows the contact of the blue limestone and the Weber shales (the "Silver" fault). Many cross-faults were also formed at about this time, which inter- sected the bed-faults, but along which movement seems to be still in progress. At a certain stage ore-bearing solutions appear to have circulated along the bed-faults, and are thought by J. E. Spurr, to have been precipitated by other solutions in the cross-faults, so that the shattered rock at the intersections became replaced with ore.' 2.08.16. Example 30e. Rico, Dolores County. Contact deposits of lead-silver ores, in Carboniferous limestones, along ' D. W. Brunton, "Aspen Mountain: Its Ores and Mode of Occurrence, ' Eng. and Min. Jour., July 14 and 21, 1888, pp. 22, 42. S. F. Emmons, "Preliminary Notes on Aspen," Proc. Colo. Sci. Sac, Vol. II., Part III,, p. 251. Rec. C. Henrich, "Notes on the Geology and on some of the Mines of Aspen Mountain," ?ran,s-. Ainer. Inst. Min. Eng., XVII,, 156. A. Lakes, "Geology of the Aspen Mining Region," Ann Rep. Colo. School of Mines, 1886. W. E. Newberry, "Notes on the Geology of the Aspen Mining District," Ti-aiis. Amer. Inst. Min. Eng., XVII., 27.3, 1889. Rec. L, D. Silver, "Geology of the Aspen (^Colo, ) Ore Deposits, ' Eng. and Min. Jour., March 17 and 21, 1888. J. E, Spurr, "Geology of Aspen Mining District," TJ. S. Geol. Survey, Monograph XXXI., 1809. Rec, 273 KEMP'S ORE DEPOSITS. intrusive porphyries. Considerable base bullion has been shipped. There are coals in the vicinity, but the operation of the smelter has been somewhat intermittent. The IsTewman Hill mines are mentioned under "Silver." ' Note. — ^Example 30/ will be found after Example 31, which has been inserted for geographical reasons. 2.08.17. Example 31. Red Mountain, Ouray County. Oxidized lead-silver ores passing in depth into sulphides, in large and small cavities, in knobs of silicified andesite. The cavities have a close resemblance to caves, but differ from ordi- nary caves in not being in limestone. They permeate the mountain in an irregular way, and mark the courses of old hot spring conduits. The andesite is generally altered to a mass of quartz, but the process is thought by S. P. Emmons to have taken place at a considerable depth, and that the quartz is a residual deposit left by the removal of more soluble elements of the andesite. T. B. Comstock regards them as hot spring deposits.^ SOUTH DAKOTA. 2.08.18. Example 30/. Galena (town), in the Black Hills. Deposits of galena in part altered to carbonate, in Cambrian (Potsdam) sandstone, near intruded sheets of trachyte. Th? ore occurs in local enrichments distributed at irregular inter- vals through the sandstone. It is rarely found in the overly- ing limestones of the Carboniferous. The ore bodies are closely akin to the so-called "siliceous, "or "Potsdam" gold ores, later described. Galena and Carbonate are the best known localities.' ' M. C. IhlseAg, "Eeview of the Mining Regions of the San Juan," Ann. Rep. Colo. School of Mines," 1885, p. 43. ^ T. B. Comstock, " Hot Spring Deposits in Red Mountain, Colorado," Trans. Amer. Inst. Min. Eng., XVIII., 261. S. F. Emmons, "Notes on Some Colorado Ore Deposits," Proo. Colo. Sci. Soc, Vol. II., Part II., p. 97. M. C. Ihlseng, "Review of the Mining Interests of the Sau Juan Region," Ann. Rep. Colo. School of Mines, 1885, p. 46. T. E. Schwartz, " The Ore Deposits of Red Mountain, Colorado," Trans. Amer. Inst. Min. Eng., XVm., 139, 1889: Proo. Colo. Sci. Soc, Vol. III., Part I., p. 77. " F. R, Carpenter, "Ore Deposits of the Black Hills of Dakota," Trans. Amer. Inst. Min. Eng., 1889, Vol. XVII., p. 570. See also report by Dr. Carpenter on the geology, etc. , of the Black Hills, to the trustees of the Dakota School of Mines, 1888,- p. 124. S. F. Emmons, Tenth Census, Vol. XIII., p. 91. LEAD AND SILVER. 373 MONTANA — IDAHO. 2.08.19. Example 33. Gleodale, Beaver Head County. Ore bodies of argentiferous galena, zincblende, copper and iron pyrites, and their oxidation products, occurring parallel with the stratification planes of a blue-gray limestone, of age not yet determined. These deposits constitute the Hecla mines, and are in the southwestern part of the State. They offer some parallel features with those of southeastern Missouri. (Exam- ple 23.) They differ from Example 30 in not being associated, so far as known, with igneous rocks/ 3.08.20. Example 33a. Wood River, Idaho. Bodies of argentiferous galena and alteration products, irregularly dis- tributed in limestone, of age as yet undetermined. Southwest- ern Idaho is largely formed of granite, southeastern is cov- ered by the immense fissure outpourings of basalt along the Snake River. North of these, and on the flanks of the gran- ite, are slates and limestones, especially on the Wood River. The latter contain the lead-silver ores. They are not in immediate association with igneous rocks, and from published descriptions appear to be somewhat irregularly distributed, although possi- bly connected with fissures. The stuctural relations with Ex- ample 23 may again be referred to. The neighboring slates and granite contain gold and silver veins, which are taken up later on. Several small smelters have been erected in the region, and have been intermittently operated. The country is really in the northern end of the Great Basin. ^ 3.08.21. Example 33. Wickes, Jefferson County, Mont. Fissure veins near the contact of granite and liparite, but cut- ting both rocks and carrying in a gangue of quartz the ores, galena, zincblende, copper and iron pyrites, and mispickel. The liparite is said by Lindgren to be Cretaceous or Tertiarj-, Wickes is just south of Helena, and was one of the first places in the West to establish successful concentration. There are two companies, the Helena and the Gregory, both large pro- ducers. ' S. F. Emmons, Tenth Census, Vol. XIII. , p. 97. " G. F. Becker, Tenth Census, Vol. XIII., p, 55. Eng. and Min. Jour,, July 2, 1887, p. 2. Rep. Director of the Mint, 1882, p. 198. G. H. Eldredge, XVI.; Ann. Rep. Dir. U. S Geol. Survey, II., 264. Rec. J. B. Hastings, Eng. and Min. Jour., March 25, 1895, 268. 274 KEMP'S ORE DEPOSITS. 3.08.22. Example 34. Coeur d'AlSne, Idaho. Galena and very subordinate alteration products, in a mineralized zone having a well-marked footwall and an impregnated, brecciated hanging of the same rock. The ore is in large chutes, vs^hioh fill innumerable small fractures in the rock. The mines are iii Wardner Canon, in the Bitter Eoot Mountains, northern Idaho. The rocks are quartzite, and thin beds of schists, much folded along east and west axes. In this way they became faulted and shattered, and in the principal mineral belt afforded an opportunity for the ore to deposit. The gangue is siderite. The mines are extremely productive and are the chief sources of ore supply for lead smelbers in Montana and on the Pacific coast.' Detailed descriptions are much needed. UTAH. 2.08.23. Example 35. Bingham and Big and Little Cot- tonwood Canons, Utah. Bed veins, often of great size, contain- ing oxidized lead-silver ores above and galena and pyrite below the water level, in Carboniferous limestones, or underlying quartzite, or on the contact between the two. The mines are situated in the Oquirrh and Wasatch Mountains, southwest and southeast of Salt Lake City, in canons well up toward the summits. The region is much disturbed, and there are great faults and porphyry dikes and knobs of granite associated with the sedimentary rocks. The ores occur in belts, extending con- siderable distances, and these in places have the rich chutes or chimneys of oxidized products. In Bingham Canon an im- mense bed of auriferous quartz is found, overlying the lead zone and next the hanging. Some peculiarity about the gold prevents its easy treatment, but much of the rock is very low grade. Recently very extensive deposits of copper ore have been found in the Highland Boy. Other fissure veins in the massive rock of the region are known, but are of less import- ance. The general geological relations suggest the deposits mentioned under Example 30 and subtypes. The mines were the occasion of the first development of the lead-silver smelters in the West, and have made Salt Lake City an important cen- ' J. E. Clayton, "The Coeur d'Alene Silver-lead Mines," Eng. and Min. Jour., February 11, 1HS8, p. 108. r s « o •8 N ^ .S "« S Si c^ '^ =»-> 1 1 c o Qi fS e 3 ■+* ao 'Bi 1 •pa 5- t^^ .Si S I 00 OS 6 '^"^w ■ > ' ' T • — !^, « ^ ' Fia. 99. — View of the tenon of Mammoth, Tintie district, Utah. From a photograph by L. E. Riter, Jr. , 1898. Fig. 100.— Bullion and Beck Mine and Mill, Eureka, Tintie district, Utah. From a photograph by L. M. Biter, Jr., 1898. LEAD AND SILVER. 275 ter of the industry. The Telegraph group, the Emma, Flag- staff, and others were famous mines in their daj'. As will appear, nearly all the Utah mines are productive of lead-silver ores. 3.08.24. Example 35a. Tooele County. Bed veins in limestone, or between it and quartzite, and containing lead- silver ores with others, in rich chutes. The deposits occur in the west side of the Oquirrh range, in Ophir and Dry canons, over the divide from Bingham. The principal mine is the Honorine. Fissure veins also occur in the region, but are of less importance. The Deep Creek district, near the Nevada line, is mentioned under 2.11.04.' 2.08.25. Example 356. Tintic District. Ore beds or belts, three in number, and one to three miles long, generally paral- lel with the stratification of vertical blue limestones, but some- times running across them. The ore-bearing zone is from 300 to 600 feet wide in at least one belt, and bears in places rich chutes of cai bonate ore. The Crismon-Mammoth has been referred to under "Copper" (Example 20g), as it contains much copper. The ore is thought by Hollister to have replaced the limestone. ^ Passing mention should also be made that lead-silver ores occur in Summit County, at the Crescent and other mines. 2.08.26. Example SOgr. Horn Silver Mine, Beaver 'County. A great contact fissure between a rhyolite hanging wall and a limestone footwall, and carrying, at the Horn Silver mine, oxidized lead-silver ores, chiefly anglesite, with considerable ' W. P. Blake, "Brief Description of the Emma Mine,' Amer. Jour. Sci., ii., II., 316. C. E. Fenner, "The Telegraph Mine," School of Mines Quarterly, July, 1893. O. J. Hollister, " Gold and Silver Mining in Utah," Trans. Amer. Inst. Min. Eng., XVI., 3. Rec. D. B. Huntley, Tenth Census, Vol. XIII, p. 407. G. Lavagnino, "The Old Telegraph Mine," Trans. Amer. Inst. Min. Eng., XVI., S.i. " Little Cottonwood and Bing- ham, Utah," Eng. and Min. Jour., August 14, 1880, p. 106; also July 19, 1889. J. S. Newberry, School of Mines Quarterly, 1884, p. 329. R. W. Raymond, Mineral Resources West of the Rocky Mountains, 1868-76, and J. R. Brown, Ibid., 1867-68. Ann. Reps, of Director of the Mint. B. Sil- Hman, " Geological and Mineralogioal Notes on Some Mining Districts of Utah," Arner. Jour. Sci., iii.. Ill , 195. ' D. B. Huntley and O. J. Hollister, as above, under last footnote. J. S. Newberry, Eng. and Min. Jour., September 13 and 30, 1879. A report on the district is in press with the U. S. Geological Survey. 276 KEMP'S ORE DEPOSITS. barite, and with many other rarer minerals. The town of Frisco, containing the mine, is at the southern end of the Grampian Mountains. The great fissure is known for two miles, but is proved valuable only between the lines of the Horn Sil- ver mine. It strikes north and south and dips 70° east. In the neighborhood of the vein the rhyolite is largely altered to residual clay. The mine is very dry, and the entire region lacks good water. The vein in general varies from 30 to 60 feet, but has pinched twi(!e in going down, and of late j'ears has largely ceased producing, although there may yet be much ore below. The ores are smelted near Salt Lake, and the base bullion is refined at Chicago. Some free milling ore has been afforded.' 2.08.27. Example 33a. Carbonate Mine, Beaver County. A fissure vein in hornblende andesite, filled with rounded frag- ments of wallrock, which are cemented by residual clay and galena. Some oxidized products occur near the surface. The mines are two and a half miles northeast of Frisco, but are in a different eruptive rock from that forming the walls of the Horn Silver. The literature is the same as for Example dOg, especially Hooker, 1. c. p. 470. 2.08.28. Example 33&. Cave Mine, Beaver County. Cham- bers irregularly distributed in the limestone, and more or less filled with limonite and oxidized lead-silver ores. Small lead- ers of ores, which mark old conduits, connect the chambers. Up to 1880 five large and fifteen small chambers had been found. They are of very irregular shape, and have a vacant space of from one to ten feet between the ore and the roof. This deposit was the typical one cited by Newberry as illustrat- ing the chamber or cave form of deposit. According to this view, the chambers were formed before the ore was brought in. It is also possible that the ore bodies have been deposited by replacement of the limestone with sulphides, as is known abun- dantly elsewhere, and that the alteration of these to oxides has occasioned the apparent caves. The products of the mine afford but 5 to 1% lead, but are valuable as an iron flux to the ' O. J. Hollister, " Gold and Silver Mining in Utah," Trans. Ainer. Inst. Min. Eng. , XVI. , 3. Rec, W. A Hooker. Report quoted in the Tenth Census, Vol. XIII., p. 464. LEAD AND SILVER. 277 neighboring smelters. The mines are in the Granite range, seven miles southeast of Milford.^ Note. — Although the larger part of the Utah mines are for lead and silver, several others of great importance will be taken up under "Silver" itself. NEVADA. 2.08.29. Example Sf). Eureka. Bodies of oxidized lead- silver ores in much faulted and fractured Cambrian limestone, with great outbreaks of eruptive rocks near. The Eureka geo- logical section is one of the most interesting in the entire coun- try, and involves some 30,000 feet of Paleozoic strata, divided as follows; Cambrian quartzite, limestone, and shale, 7,700 feet; Silurian limestone and quarztite, 5,000 feet; Devonian limestone and shale, 8,000 feet; Carboniferous quartzite, lime- stone, and conglomerate, 9,300 feet. These have afforded some extremely valuable materials for comparative studies with homotaxiai strata in the East. The ore occurs especially in what is called the Prospect Mountain limestone of the Cam- brian, one smaller deposit being also known in Silurian quartz- ite. The limestone has been crushed and shattered along a great fault, and through its substance ore solutions have circu- lated, replacing it in part with large bodies of sulphides which have afterward become oxidized to a depth of 1,000 feet. The ore bodies were puzzling as regards their classification, and a famous mining suit, with mauj' interpretations from various experts, resulted. The alteration of the ore has caused shrink- age, and the formation of apparent caves over it. But there are many empty caves, formed by surface waters long after the ore was deposited, and J. S. Curtis very clearly shows that the ore bodies originated by replacement. All are connected with more or less' strongly marked fissures which formed the con- duits. Mr. Curtis made a careful series of assays of the neigh- boring igneous rocks to find some indication of the source of the ore. A quartz porphyry gave significant results, and to this the metals are referred, the portions of the mass at a great ' O. J. Hollister, "Gold and Silver Mining in Utah," Trans. Amer. Inst. Min Eng., XVI., 3. D. B. Huntley, Tenth Census, Vol. XIII , p. 474. J. S. Newberry, School of Mines Quarterly, March. 1880. Reprint, p. 9. Cf. also J. B Kimball. "The Silver Mines of Eulalia, Chihuahua," Amer. Jour. Set. ii.. XLIX-, 161. 278 KEMP'S OMIS DEPOSITS. depth are considered to have furnished them. Eureka was one of the first places in this country where the hypothesis of replacement was applied to ores in limestone. The district is now far less productive than it was fifteen or twenty years ago.' Fig. 101. — Section at Eureka, Nev. Reproduced in line work after colored plate by J. S. Curtis. Monograph VI., U. 8. Oeol. Survey. ' G. P. Becker, Tenth Cenms, Vol. XIII., p. 33. Rec. W. P. Blake, " The Ore Deposits of the Eureka District, Nevada," Trans. Amer. Inst. Min. Eng., VI,, 554. J. S, Curtis, "Silver-lead Ore Deposits of Eureka, Nev.," Monograph VII. , U. 8. Oeol. Survey. A. Hague, "Geology of the Eureka District," Monograph XX., U. 8. Geol. Survey. Abstract in Tliird Ann. Rep. Director U. 8. Oeol. Surveg. W. S. Keyes, "Eureka Lode of Eureka, Nev.," Trans. Amer. Inst. Min. Eng., VI., 344. J. S. Newberry, School of Mines Quarterly, March, 1880. R. W. Raymond, "The Eureka- Richmond Case,". Trans. Amer. Inst. Min. Eng., VI., 371. C. D. Walcott, "Paleontology of the Eureka District," Monograph VIII, U. S. Oeol. Survey. LEAD AND SILVER. 379 ARIZONA — CALIFORNIA. 2.08.30. Comparatively small amounts of lead ores are ship- ped from Arizona from time to time, chiefly from Cochise County (Tombstone region) and Pima County (Tucson region). They will be mentioned under "Silver." Insignificant amounts are also afforded by California (about $2,000 in 1889), mostly from Inyo County. (See Eleventh Census, Bull. No. 80, June 18, 1891.) CHAPTER IX. SILVEK AND GOLD. —INTRODUCTORY : EASTERN SILVER MINES AND THE ROCKY MOUNTAIN REGION OP NEW MEXICO AND COLORADO. 3.09:01. The two "precious'' metals are so generally asso- ciated that they cannot be separately treated. While endeav- oring to preserve the distinctive impression given by examples, it is practically impossible to set forth all the widely varying phenomena of the silver-gold veins of the West in any other than an approximate way. Hence geographical considerations are placed first and where markedly similar ore bodies in'dif- ferent States are to be grouped together cross references are given. The following general examples have been made be- cause their individual features are based on those geological relations which are most vitally concerned with questions of origin. 3.09.02. Example 37. Veins containing the precious met- als usually with pyrite, galena, chalcopyrite, and less common sulphides, sulpharsenides, sulphantimonides, etc., in igneous rocks. No special subdivision is made on the character of the gangue, which may be quartz, calcite, barite, fluorite, etc., one or all. The first named is commonest. A great and well- defined original fissure is not necessarily assumed, but some crack, or joint or crushed strip must have directed the ore- bearing solutions, which may have then replaced the walls in large measure. For other structural features see the discussion of veins (1.05.01); compare also Example 17, Butte, Mont. Example 37a. Replacements more or less complete of igneous dikes, which have usually been described as porphyry. Compare Example 17a under "Copper" (Gilpin County, Colo- rado), and Example 20d (Santa Rita, N. M.). Ore and gangue. where the matrix is not the dike rock, as in Example 37. SILVER AND GOLD. 281 Example 38. CoEtact deposits between two kinds of igneous rock or between two different flows. Ore and gangue as in Example 37. Example 39. Agglomerates of rounded, eruptive boulders, bombs, etc., in abandoned volcanic necks or conduits, and coated with ores. "The Bassick mine of Custer County, Colo- rado, is the only example of an ore deposit of this kind yet identified. Example 40. Contact deposits between igneous and sedi- mentary rocks. No subdivisions are made on the kind of rocks. Ore and gangue as in Example 37, The ore body may replace a calcareous rock along the under side of an intruded sheet. Com- pare also Example 20, "Arizona Copper"; Example 21a, " Triassic Copper" ; Example 30, "Leadville"; and Example iOg, "Horn Silver Mine." Example 41. Veins in sedimentary rocks, generally cutting the bedding, but at times parallel with it. Lateral enlarge- ments are frequent. The ore body may be largely due to the replacement of some calcareous rock, such as limestone or lime- shales, beneath some relatively impervious bed. Ore and gan- gue as in Example 37. Example 42. Veins cutting both sedimentary and igneous rocks, and therefore due to disturbances after the intrusion of the latter. Ore and gangue as in Example 37. No special examples are made for metamoiphic rocks. 2.09.03. Minerals containing silver or gold. Ag. S. As. Sb Native silver 100. Argenite (silver glance), Ag^S 87.1 Prousite (light ruby silver), SAg^S.ASjSa . . 65.5 Pyrargerite (dark ruby silver), SAgsS.SbsSj 60. Stephanite (brittle silver), SAg^S.SbgSj. ... 68.5 Cerargerite (horn silver), AgCl 75.3 13.9 19.4 15.1 17.8 .... 23.2 .. 16.3 .... 15.3 .. Cl. 24. Silver also occurs with galena (Cf."Lead") and with tetra- hedrite (Cf. "Copper"). Gold occurs combined with tellu- rium in teliurides; mechanically mingled with pyrites; and as the uncombined native metal. From a metallurgical point of view the ores of the precious metals are divided into two classes. 1. Those whose amount of precious metal amalga- mates readily with quicksilver, and is thus obtained with com- 382 KEMP'S ORE DEPOSITS. parative ease — the free milling ores, 2. Those which require roasting or some previous treatment before amalgamation, chlorination, or similar process, or which must be smelted pri- marily for lead or copper, from which the precious metals are afterward extracted — the rebellious ores. In the subsequent description the endeavor has been made to work from the dis- tinctively silver mines to those of gold, where geographically possible/ The precious metals seem to have been derived in almost all cases from deep-seated sources, and presumably from igneous rocks, even though they may now be found in sediments or metamorphic rocks. The valuable and thorough researches of J. R. Don upon the Australian gold-bearing reefs, the neighbor- ing wall rocks, and the sea water as a possible source of the precious metal have led to increased faith in its derivation by uprising solutions. Both Blake and Merrill have discovered ' Ann. Reps. Directors of the Mint. Reo. W. P. Blake, "The Various Forms in which Gold Occurs in Nature," Rep. Director of the Mint. 1884, p. 573. Eec. " Gold in Granite and Plutonic Rocks," Trans. 4mer Inst. Min. Eng., XXVI., 290, 1896. Brown, Raymond, and others, 186S to 1876, "Mineral -Resources West of the Rocky Mountains.' Annual. T. C'. Chamberlin, " On the Geological Distribution of Argentiferous Galena," Oeol. of Wis., Vol. IV. Cumenge and Robellaz, "L'Or dans la Nature." Paris, 1879. L. De Launay, "Contribution a I'etude des Gites Metal- liieras, Annales des Mines, August, 1897, 108. J. R. Don, "The Genesis of Certain Auriferous Lodes," Trans. Amer. Inst. Min. Eng., XXVII., 564, 1897. Reo. J. F. Kemp, "Geological Occurrence and Associates of the Telluride Gold Ores," The Mineral Industry, VI., 395-320, 1898. Clarence King, " Production of the Precious Metals in the United States," Second Ann. Rep. Director U. S. Oeol. Survey, p. 333. A. G. Look, Gold, 1882. G. P. Merrill, "Gold in Granite," Amer. Jour, of Set., April, 1896, 309. Mineral Resources of the U. S. ; annual publication of the Geological Survey. R. I. Murchison, "General View of the Conditions under which Gold is Dis- .tributed," Quar. Jour. Geol. Soc, VII., 134. Also in Siluria anA Amer. Jour. Sci., ii., XVIII., 301. J. S. Newberry, " On the Genesis and Distri- bution of Gold," School of Mines Quarterly, III., No. 1, and Eng. and Min. Jour., December 24 and 31, 1881, pp. 416, 437. R. Pearce, "On the Ores of Gold," etc., Colo. Sci. Soc. III., p. 237. J. A. Phillips, Ore Deposits, 1884. The Mining aiid Metallurgy of Oold and Silver, 1867. Tenth Cen- sus Report on the Precious Metals. Albert Williams, ' ' Popular Fallacies Regarding Precious Metal Ore Deposits," Fourth Ann. Rep. Dir. U. S. Oeol. Survey, 1884. J. H. L. Vogt, Zeitschrift fiir prakt. Geologic, Sep- tember, 1898, 331. "XJeberdie Bildung des Gediegen Silbers," etc., Idem, April, 1899, 113. SILVER AND QoLD. 283 gold in granite, and Moricke, as earlier cited, 1.03.06, observed it in obsidian. 2.09.04. Example 22a. Atlantic Border. Already men- tioned (2.06.03), the region is only of historical interest as af- fording silver, although lately some attention has been directed to Sullivan, Me., where the veins have pyrite and probably stephanite, in a quartz gangue, in slates, associated with gran- ite knobs and trap dikes, which are of later age than the veins. Some silver is generally found in the galena of the Eastern States, but the ores have never yet proved abundant enough to be important.' Mention may also be made at this point of the argentiferous galena veins along the Ouachita uplift of Arkansas. A few are known, usually with Trenton shales or slates for walls. They are low grade, and though o.ice the basis of a small ex- citement, their production has never been serious. Additional reference to the region will be found under "Antimony." Some mines of the latter metal are stated by W. P. Jenney to show low-grade, argentiferous ores in depth.'' 2.09 05. Example 42. Silver Islet, Lake Superior. A fissure vein carrying native silver, argentite, tetrahedrite, galena, blende, and some nickel and cobalt compounds in a gangue of calcite, in flags and shales of the Animikie (Algon- kian) system, and cutting a large trap dike, within which alone the vein is productive. Silver Islet is or was originally little more than a bare rock some 90 feet square, lying off the north shore of Lake Superior just outside of Thunder Bay, and within the Canadian boundaries. The native silver was de- tected outcropping beneath the water. The vein was produc- tive to a depth of 800 or 1,000 feet, but below this it yielded lit- tle. The trap dike has usually been called diorite, but is deter- mined to be norite by Wadsworth {Bull, 2, Minn. Geol. Sur- vey, p. 92), and gabbro by Irving {Monograph V., U. S. Geol. ' C. W. Kempton, "Sketches of the New Mining District at Sullivan, Me.," Trans. Amer. Inst. Min. Eng., VII., 349. M. E. Wadsworth, "Theories of Ore Deposits," Proc. Boston Soc. Nat. Hist.. 1884, p. 205. Eng. and Min. Jour:, May 17, 1884. Bull. Mus. Comp. ZoSl., 3, Vol, Vli., 181. ' T. B. Oomstock, Ann. Rep. Geol. Survey of Arkansas, 1888, Vol. I., "Gold and Silver." 284 KEMP'S ORE DEPOSITS. Survey, p, 378). Some $3,000,000 were obtained from the miue, yet the expenses were so great in. keeping up the surface works against winter gales and ice that but little profit was realized. The vein has been traced 9,000 feet, but is nowhere else productive. Considerable graphite has been found in the workings, and some curious pockets of gas.' 2.09.06. Example 42. Thunder Bay, Canada. The main- land near Silver Islet contains many similar veins. They have furnished considerable silver, as argentite in a gangue of quartz, barite, calcite and fluorite, and associated with zinc- blende, galena, and pyrite.^ THE REGION OF THE ROCKY MOUNTAINS AND BLACK HILLS. NEW- MEXICO. 2.09.07. Geology. — The general topography and geology of New Mexico were outlined in the introduction. Much remains to be done in developing its geology. The eastern part belongs to the prairie region, and is very dry. A few rivers, notably the Pecos and the Eio Grande, afford water for irrigation, the former of which is now being utilized on a grand scale, and for the latter plans have been prepared. In the central portion many subordinate north and south ranges of mountains are found, which are less elevated than those of Colorado. The Colorado ranges virtually die out at the northern boundary. The north- western portion comes in the great Colorado plateau, and has been quite fully described by Captain Button {Eighth Ann. Rep. Director U. S. Geol. Survey). In numerous localities ' R. bell, Eng. and Min. Jour., January 8 and 15, 188 7.* See also May 14, 1887. W. M. Courtis, " On Silver Islet,'' Eng. and Min. Jour., Decem- ber 21, 1873, and Trans. Amer. Inst. Min. Eng., V... 474. E. D. Ingall, Ann. Rep. Can. Geol. Survey, 1887-88, Part II., p. 14. F. A. Lowe, "Tn^ Silver Islet Mine and it^ Present Development,'' Eng. and Min. Join December 16, 1882, p. 321. T. MacFarlane, 'Silver Islet,"' Tra?!s. Amer Inst. Min. Eng., VIII., 326. Geol. of Canada, 1863, 717. Canadian Nat- uralist, Vol. rV., p. 37. McDermott, Eng. and Min. Jour , Vol XXIH., Nos. 4 and 5. '^ R. Boll, "Silver Mines of Thunder Bay,'' Eng. and Min. Jour., Jan uary 8 and 15, 1887. E. D. Ingall, Ann. Rep. Can. Survey, 1887-88, Part II., p. IH. Rec. See also Eng. and Min. Jour., M?iy 14, 1887; February 18, 1888, p. 123; May 26, 1888, p. 383. W. M. Courtis, "Animikie Rocks and their Vein-plienomena as shown at the Duncan Mine," Trans. Amer. Inst. Min. Eng., XV., 671; see also V., 473. SILVER AND GOLD. 385 throughout the Territory volcanic action has been rife, and in places is but recently extiact. The eastern part is largely Cre- taceous, and also the northwestern plateau, which contains much valuable coal. The mountain ranges often have nuclei of Archean crystalline rocks, with successive strata of Carbon- iferous, Permian, Triassic, Jurassic and Cretaceous on the flanks. The mining regions are in these ranges of mountains.' 2.09.08. The southwestern county is Grant, whose lead- silver deposits have been briefly referred to. North of Silver City are quartz veins of gold and silver ores, in diabase and quartz porphyry (Example 37), and again, west of Silver City, are ferruginous deposits with chlorides and sulphides of silver in limestone. In the Burro Mountains are silver ores in lime- stones, apparently Lower Silurian. The Santa Rita Mountains contain, in addition to the copper (Example 20d), silver and gold in quartz veins in eruptive rocks (Example 37). Lake Valley, in Dona Aiia County, has been mentioned (2.08.04). In Lincoln County gold ores are reported from the White Oak district. The principal mines of Socorro County have been ' W. P. Blake, Proc. Bost. Soc. Nat. Hist, 1859, Vol. VII., p 64. "Ge- ology of the Rocky Mountains in the Vicinity of Santa Fe," Amer. Asso. Adv. Sci., 1859. A. E. Conkling, "Report on Certain Foothills in North- ern New Mexico," Wheeler's Survey. Rep. of Chief of U. S. Engineers, 1877, II., 1298. E, D. Cope, "Report on the Geology of a Part of New Mexico," Wheeler's Survey, 1875; Appendix Gl. C. E. Dutton, "Mount Taylor and the Zuni Plateau," Sixth Ann. Rep. U. S. Geol. Survey, pp. 111-305. S. F. Emmons, Tenth Census, Vol. XIII., 100. O. Loew, "Re- port on the Geology and Mineralogy of Colorado and New Mexico. ' Wlieeler's Survey, IKT.T; Appendix G2, p. 27. J. Marcou, "The Mesozoic Series of New Mexico," Amer. Geol, IV., 1.55. 216. R. E. Owen and E. J. Cox, "Report on the Mines of New Mexico," Washington, 1865, 60 pp., Amer. Jour. Sci., ii., XL.. 391. G. F. Runton, "On the Volcanic Rocks of New Mexico," Qtiar. Jour. Geol. Soe., Vol. VI., p. 251, 18.50. B. Silli- man, Jr., "The Mineral Regions of Southern New Mexico," Trans. Amer. Inst. Min. Eng., X. , 424. F. Springer, " Occurrence of the Lower Burling- ton Lime.stone in New Mexico, ' Amer. Jour. Sci, iii. , XXVII., 9T. J. J. Stevenson, "Geological Examinations in Southern Colorado and North- ern New Mexico," Wlieclefs Survey. 1881. " Geology of Galisteo Creek," Amer. Jour. Sci.. iii., XVIII., 471. "On the Laramie Group of Southern New Mexico," Atner. Jour. Sci., iii., XXIL, 370. For the Bibliography of the Geology of the Territory in general, see Bulletin of the U. S. Geol. Survey, 127 (literature up through 1891); 130 (1892-1893); 135 (1894); 146 (1895) ; 149 (1896) ; 156 (1897), and annual issues. 286 KEMP'S ORE DEPOSITS. mentiooed (Example 39), and the copper in Permian sandstone under Example 31c. There are other silver-bearing lodes ii the Socorro Mountains near the town of Socorro. Henrich has described (1. c.) a curious deposit of quartz carrying gold and silver (the Slay back Lode) on the contact between the older bedded eruptions and a later siliceous dike in the Mogollon range (Example 38). In Santa Fe County are important placer mines (Example 44) and thin veins of galena in rhyolite. In Bernalillo County, are placers on the slopes of the Sandia Mountains. In Colfax County, in the Rocky Mountains, are other placers, and reported gold and silver mines.' COLORADO. 3.09.09. Geology. — The eastern portion contains plains and is a region lacking water. It consists of Quarternary and Cretaceous rocks. The plains rise in the foothills, which are chiefly upturned Jura-Triassic and Cretaceous strata. The Paleozoic is relatively limited, although known. It rests on the crystalline rocks of the Archean. There are some minor uplifts, running out at right angles to the Front range, that divide the foothill country into basins, and are especially important in connection with coal. Next come the easterly ranges of the Rocky Mountains, in linear north and south succession. They consist largely of dome-shaped peaks of granite, with great local developments of volcanic rocks. To the west follow the several parks, chiefly consisting of Meso- zoic strata. They are bounded by ranges again on the west, some of which, like the Mosquito range (see under Example 30), mark great lines of post-Cretaceous upheaval, and are accom- panied by immense igneous intrusions. On the east and west flanks of the Sawatch range (the granitic Continental Divide) are Paleozoic strata in considerable thickness, but to the west ' W. P. Blake, "Gold in- New Mexico," Pro6. Post. Soc. Xaf. Hist.. "VII., p. 16, July, 1859. "Observations on the Geology, etc., near i-'anta Fe," Amer. Asso. Adv. of Sci., XIII., 314, 1860. 8. F. Emmons, Tenth Census, XIII., p. 101. C. Henrich, "The Slaybaok Lode, New Mexico," Eng. and Mm. Jour., July 13, 1889, p. 37. R. E. Owen and E. T. Cox, Rep. on the Mines of New Me.vico, Washington, 1865. Rep. Director of the i)/mf, 1882, p. 339. B. Silliman, "Mineral Resources of Southern New Mexico," Trans. Amer. Inst. Min. Eng., X., 424. Eng. and 3Ii)i Jour.. October 14 and 21, isy3, pp. 199, 213. SILVER AND GOLD. 287 they dip under the vastly greater development of Mesozoic ter- ranes, which shade out into the Colorado plateau. In northern, central and southwestern Colorado are vast developments of igneous rocks that have attended the geological disturbances/ 3.09.10. The San Juan region includes several counties in southwestern Colorado, in whole or in part, viz. : Ouray, Hins- dale, San Juan, Dolores, and La Plata. The chain of the San Juan Mountains consists of great successive outflows of erup- tive rocks, andesite, diabase, diorite, basalt, etc., which cover up the Archean and later sedimentary terranes, except in a few scattered exposures. Considerable masses of rocks formed of fragmental ejectamenta are also known. All these are crossed by immense vertical veins, largely with quartz gangue, and con- taining argentiferous minerals of the usual species, galena, tetrahedrite, pyrargerite, and native silver, as well aa bismuth compounds. Gold has been quite subordinate, although late developments near Ouray have shown some peculiar and inter- esting deposits. R. C. Hills, as quoted by S. F. Emmons, 1885, traced three systems of veins. (1) Silver bearing, narrow (six inches to three feet), nearly vertical veins, with base metal ores ' G. L. Cannon, "Quaternary of the Denver Basin," Proc. Colo. Sci. Soc, III., 48. See also III., 200. "Geology of Denver and Vicinity,"' Idem, TV., 235. Rec. W. Cross, "The Denver Tertiary Formation,' Amer. Jour. Sci., iii., XXXVII., 261. "Pike's Peak," Atlas Folio, U S. Oeol. Survey, No. 7. Rec. "On a Series of Peculiar Schists near Salida," Proc. Colo. Sci. Soc, IV., 286. Rec. "The Laccolitic Mtn. Groups of Colorado, Utah and Arizona," Ann. Rep. Dir. U. S. Oeol. Sur- vey, XIV., 165. Rec. G. H. Eldredge, "On the Country about Denver, Colo.," Proc. Colo. Sci. Soc, III., 86. See also 140. S. F. Emmons, " Orographic ilovements in the Rocky Mountains, " Geol. Soc. of America , I., 24.V286. F. U. Endlich, "On the Eniptive Rocks of Colorado, " Tenth Ann. Hep., Hayden's Survey. H. Gannett, "Report on the Arable and Pasture Lands of Colorado," Hayden's Survey, 1876, p. 313. H. C. Free- man, ".The La Plata Mountains," Trans. Amer. Inst. l\Iin. Eng., XIII, 681. G. K. Gilbert, "Colorado Plateau Province as a Field for Geological Study," Amer. Jour. Sci., iii., XII., 16, 85. J. D. Hague, Fortieth Paral- lel Survey, Vol. HI., p. 475. F. V. Hayden, Reps, of Hayden's Survey, 1873, 18'r4, p. 40; 1875, p. 33; 1876, pp. 5, 70. R. C. Hills, "Preliminary Notes on the Eruptions of the Spanish Peaks," Proc. Colo. Sci. Soc, III., 24, 224. "The Recently Discovered Tertiary Beds of the Huerfano River Basin," Proc. Colo. Sci. Soc, III., pp. 148, 217. "Jura-Trias of South- eastern Colorado," Amer. Jour. Sci, iii., XXIII., p. 243. "Orographic and Structural Features of Rocky Mountain Geology," Proc Colo. Sci 288 KEMP'S ORE DEPOSFl'8. and no selvage. (2) Large, strong, gold-bearing veins dipping 60° with selvages and intersecting (1). (3) Like (l), but larger and more persistent, and carrying occasional bismuth and anti- monial ores with gold and little or no silver. T. B. Comstock {Trans. Amer. Inst. Min. Eng., XV., 218) has classified the veins in three radiating systems. (1) The northwest, with tetrahedrite (freibergite). (3) The east and west, with bismuth and less often nickel and molybdenum. (3) The northeast, with tellurides and antimony and sulphur compounds of the precious metals. Quite recently a series of small caves near Onray, in quartzite overlaid by bituminous shales have been found to contain native gold, and have excited great interest. It is thought by Endlich that they represent inclusions of shale, now dissolved away, and that the gold was precipitated on the walls. If this view is correct, they mark one of the very few illustrations of chamber deposits which are known. More extended mining work has proved them to be in all cases connected with a supply fissure from which small leaders guide the miners to the chambers. In the vicinity of Telluride there is a very interesting devel- opment of veins. One of the most remarkable and persistent ^Soc, III., 362. Eec. "Types of Past Eruptions in the Rocky Mountains," ' Idem, TV., 14. Eec. A. Lakes, " Extinct Volcanoes in Colorado," ^me?-. Geol., January, 1890, p. 38. Oscar Loew, "Report on the Minerals of Colorado and New Mexico," Wheeler's Survey, 1875, p. 97. "Eruptive Rooks of Colorado," Wheeler's Survey, 1873. C. A. H. McCauley, "On the San Juan Region, " Rep. Chief of U. S. Engineers, 1878, III. , p. 1753. C. S. Palmer, "On the Eruptive Rooks of Boulder County," etc., Proc. Colo. Sci. Sac, III., p. 230. A. C. Peale, "On the Age of the Rocky Mountains in Colorado," Amer. Jour. Sei., iii., XIII., p. 172; Reply to the above by J. J. Stevenson, Amer. Jour. Sei., iii., 2CIII., 297. T. A. Rick- ard, "Gold Resources of Colorado," The Mineral Industry, 11., 325; IV., 315. S. H. Soudder, "The Tertiary Lake Basin at Florissant," iTai/den's Survey, 1878, p. 271; see also 1877. J. A. Smith, Catalogue of the Princi- pal Minerals of Colorado, Central City, 1870. J. J. Stevenson, " Notes on the Laramie Group of Southern Colorado," ^nter. Jour. Sci., iii., XVIII., 139. "TheMesozoic Rocks of Southern Colorado," J.mer. Qeol., III., p. 391. P. H. Van Diest, " Colorado Volcanic Cones," Proc. Colo. Sci. Soc, III., p. 19. C. A. White, "On Northwestern Colorado," MjiWi .Anw. Rep. Director U. 8. Geol. Survey, 683-710. For the complete geological bibli- ography of the State, see Bulletins U. S. Geol. Suney, 127 (1732-1891) ; 180 (1892-93); 135 (1894); 146 (1895); 149 (1896); 156 (1897), and current annuals. SILVER AND QOLD. 289 is the Smuggler, recently described by J. A. Porter. It is known for a stretch of four miles and cuts the high divide that Hot Classified 1 ^ 1 as to Geologic Age. 1 ^ Hhyolites and Andesites. San Juan Formation Andeeitic Breccia Jurassic and Cretaceous Shales and Sandstones. Fig. 103. — Geological sketeh-map of the Telluride district, Colorado. AJter Arthur Winslow, Trans. Amer. Inst. Mi/n. Eng., February, 1899. separates the Marshall hasin near the town of Telluride, on the south, in the drainage area of the San Migbel River, from 290 KEMP'S ORE DEPOSITS. the valleys of Canon Creek, a tributary of the Uncompahgre Eiver, that lies to the north. (See Fig. 102.) The summit of the divide is 13,200 feet above tide. Whitman Cross has been mapping an atlas sheet for the U. S. Geological Survey in the vicinity of Telluride, and has prepared in advance of its issue a sketch of the local geology. ("The San Miguel Formation, Igneous Books of the Telluride District," Proc. Colo. Sci. Soc, September, 1896.) The formations of interest in connection with the vein, begin with the San Miguel conglomerate, which is probably of closing Cretaceous or early Eocene age. On this is the San Juan formation, 2,000 feet thick, of bedded volcanic andesitio tuffs, the chief wall rocks. Above follow sheets of various andesites and rhyolites, which are cut by the highest parts of the vein. The fissure containing the ore body has cut this series and is known for 3,500 feet vertically, but what its character is in the San Miguel conglomerate is not yet demon- strated. The gangue is chiefly quartz, with some rhodochrosite, calcite, siderite and barite. The values in silver are highest at the north, and yield to gold values to the south. Two other notable veins cross and fault the Smuggler, one the Pandora, containing auriferous quartz, the other the Revenue, with con- siderable lead. So constant is the character of the Smuggler thatstoping ground has been broken for a mile without a break. (J. A. Porter, "The Smuggler-Union Mines, Telluride, Colo.," Trans. Anier. Inst. Min. Eng., XXVI., 449.) The region is indeed one of remarkably persistent and clear-cut fissures,^ which are shown on Fig. 102. Placer gold mines (Example 44) are quite extensively worked in San Miguel County. J. B. Farish has de- scribed the veins at Newman Hill, near Rico, in a valuable paper cited below. The lowest formation exposed is magnesian limestone, supposed to be Carboniferous. It contains large ore bodies of low grade, and is also, strangely enough, heavily charged with carbonic acid gas. Above this for 600 feet are alternating sandstones and shales, and then a narrow stratum of limestone 18 to 30 inches thick. This is followed by about ' C. W. Purington, " Preliminary Report on the Mining Industries of the Telluride Quadrangle,' Eighteenth Ann. Rep. Director U. S. Geol. Survey. Arthur Winslow, " The Liberty Bell Gold Mine, Telluride, Colo- rado," Trans. Amer. Inst. Min. Eng., February, 1899. SILVER AND GOLD. 291 292 KEMP'S ORE DEPOSITS. 500 feet additional of shales and sandstone, regarded as Car- boniferous. Fifty feet above the lowest limestone a laccolite of porphyrite has been intruded. Two sets of fissures are pres- ent—one nearly vertical and striking northeast, the second dip- ping 30 to 45° northeast, and striking ndrthwest. The former are the richest, are rudely banded and persistent, being worked in one case for 4,000 feet. The flatter fissures are less rich. The principal ore bodies, however, occur as horizontal enlarge- ments of both these sets of veins. Just over the thin bed of limestone mentioned above the ores have spread out into sheets from 20 to 40 feet wide, and from a few inches to three feet thick. They consist of solid masses of the common sulphides, galena, pyrite, gray copper, etc., and are very rich. Above Fig. 104. — Oeological cross sections of strata and veins at Newman Hill, near Rico, Colo. After J. A'. Parish, Proc. Colo. Sci Soc, April 4. 1893. See also Figures 5 and 6. them the fissures a;pparently cease, or at least are tight. Two hundred feet down from them the vein filling becomes nearly barren, glassy quartz. These are most remarkable ore bodies, and would appear to have been formed by uprising solutions, which met the tight place and spread sidewise, depositing their minerals; but as Mr. Farish advances no explanation, it is hardly justifiable for others, less familiar than himself with the phenomena, to do so. T. A. Rickard has also written of them, and has illustrated the details of vein structure in a very significant series of plates, which show the banding to be ir- regular and not persistent. He has also introduced some cor- rected interpretations of the faults. The lead-silver ores of Red Mountain and Rico have al- SILVER AND GOLD. 293 ready been mentioned (2.08.17). Silverton and Ouray are the principal towns of the San Juan.' 2.09.11. The new mining region of Creede, now decided to be in Saguache County, should be mentioned in this connec- tion. It is situated near the junction of Saguache, Ouray and Hinsdale counties, and some ten or twelve miles from Wagon Wheel Gap. There is a great development of igneous rocks as well as of Carboniferous limestone, but the veins as yet devel- oped are in the former. They appear to be fissure veins, and have quartz, in large part amethyst, with some manganese minerals as a gangue, and, with these, oxidized silver ores. The mines are on two mountains. Bachelor and Campbell, which are on opposite sides of Willow Creek Canon. ^ ' T. B. Comstock, "The Geology and Vein Structure of Southwestern Colorado," Trans. Amer. Inst. Mia Eng., Vol. XV., 218: also XI., 16.5, and Eng. and Min. Jour., numerous papers In 1885. " Hot Spring Formation in the Red Mountain District, Colorado," Trans. Amer. Inst. Min. Eng., XVII., 261. S. F. Emmons, "On the San Juan District," Eng. and Min. Jour., June 9, 1883, p. 332. "Structural Relations of Ore Deposits," Trans. Amer. Inst. Min. Eng., XVI., 804. Rec. Tenth Census, Vol. XIII., p. 60. F. M. Endlich, "Origin of the Gold Deposits near Ouray," Eng. and Min. Jour., October 19, 1889. " San JvLnnJiistrict," Hayden's Survey, 1874, p. 229. Ibid., 1875, Bull. Ill, Amer. Jour. Scl, iii., X., 58. J. B. Farish, "On the Ore Deposits of Newman Hill, near Rico, Colo.,' Colo. Sci. Soc, April 4, 1892. Rec. W.H.Holmes, " 1^0, Plaia, District," Hayden.'s Siirveij. 1875; Amer. Jour. Sci., iii., XIV. , 420. M. C. Ihlseng, "Review of the Mining Interests of the San Juan Region," Rep. Colo. State School of Mines, 1885, p. 27. G. E. Kedzie, "The Bedded Ore Deposits of Red Mountain Mining District, Ouray County, Colorado," Trans. Amer. Jn.sf. 3Iin. Eng., XV., aiO. Rec. G. A. Koenig and M. Stocker, " Lustrous Coal and Native Silver in a Vein in Porphyry, Ouray County, Colorado," Trans. Amer. Inst. Min. Eng., IX,, 650. T. A. Rickard, " Vein Structure in the Enterprise Mine." Proc. Colo. Sci. Soc, Adv. Sheets, Vol. V. T. E. Schwartz, "The Ore Deposits of Red Mountain, Ouray County, Colorado,' Trans. Amer. Inst. Min. Eng., XVIII., 139, 1889. J. J. Stevenson, "On the San Juan," Wheeler'S' Survey. III., p. 376. "The San Juan Region," Eng. and Min. Jour., August 27, 1881, p. 136; September 24, 1881, p. 201; July 17, 1880; December 20, 1879; and many other references in 1879 and 1880. P. H. Van Diest, "Notes on a Trip to Telluride, San Miguel Co., Colo.," Proc. Colo. Sci. Soc, II.. 28, 1885; Idem, January, 1886. ^ E. B. Kir by, "The Ore Deposits of Creede and their Possibilities," Eng. and. Min. Jour., March 19, 1892, p. 325. Rec. T. R. MacMechen, "The Ore Deposits of Creede," Eng. and Min. Jour., March 12, 1892, p 301. Rec. 394 KEMP'S ORE DEPOSITS. 2.09. 12. The Gunnison region lies on the western slope of the Continental Divide, and embraces both mountains and pla- teaus. West of the main and older range are the later Elk Mountains, in which several mining districts are located. Aspen has already been mentioned, and the long series of ore bodies in the Carboniferous limestones. The other principal districts are Independence, Ruby, Gothic, Pitkin and Tin Cup. The ores at Independence are sulphides with silver, in the Archean granite rocks. In the Tin Cup district the Gold Cup mine is in a black limestone and contains argentiferous cerussite and copper oxide. In the Ruby district the ores are in the Cretaceous rocks, and in the Forest Queen they are rnby silver and arsenopyrite, partly replacing a porphyry dike. On Copper Creek, near Gothic, a series of nearly vertical fissures traverse eruptive diorite. They contain sulphide of silver and native silver. The Sylvanite is one of the principal mines. Arthur Lakes has described some very curious veins in Gunnison Co., the Vulcan and Mammoth, that contain opaline silica and native sulphur together with pyrites.^ 2.09.13. Eagle County. The lead-silver mines of Red Cliff have already been mentioned (Example 30c), and also the underlying gold deposits. The Homestake mine, northwest of Leadville, over toward Red Cliff, is on a vein of galena in granite, and was one of the first openings made in the region.^ 3.09.14. Summit County. The Ten-Mile district, which is the principal one, has been mentioned under Example 30a. Lake Countj^, containing Leadville, has been treated under Example 30. Mention should also be made of the placer depos- ' F. Amelung, " Sheep Mountain Mines, Gunnison County, Colo.," Eng. and Min. Jour., August 28, 1886, p. 149. F. M. Chadwick, "The Tin Cup Mines, Gunnison County, Colorado,'' Eng. and Min. Jour., January 1, 1881, p. 4. See also Example 12d for iron mines. J. E. Holibaugh, "Gold Belt of Pitkin, Gunnison Co., C'olo.,"^«5f. and Min. Jour., Decem- ber 12, 1896, p. 5.59. Arthur Lakes, "Sketch of a Portion of the Gunni- son Gold Belt, " etc.. Trans. Amer. Inst. Min. Eng., XXVI., 440. = F. Guiterman, "On the Gold Deposits of Red Cliflf," Proc. Colo. Sei. Soc, 1890. "On the Battle Mountain Quartzite Mines," Mining Industry, Denver, January 10, 1890, p. 28. E. E. Oloott, "Battle Mountain Mining District, Eagle County," Enx}. and Min. Jour.. June 11 and 18, 1887, pp. 417, 436; May 21, 1893. G. C. Tilden, "Mining Notes from Eagle County," Ann. Rep. Colo. State School of Mines, 1886, p. 139. SILVER AND GOLD. 5i95 its in California Gulch, which first attracted prospectors to the region in 1860. In its eastern part Summit County borders on Clear Creek County, and at Argentine are some veins related to those of the latter. They are high up on Mount McClellan, and are remarkable for the veins of ice that are found in them.' 2.09.15. Park County, which lies east of Lake County and embraces the South Park, has some mines on the eastern slope of the Mosquito range, and in the Colorado range, to the north- west. The latter are similar in their contents to the George- town silver ores, mentioned under Clear Creek County, but the former are bodies of argentiferous galena and its alteration products in limestone and quartzite. Pyrite is also abundant, and at times a gangue of barite appears. The mines are in the sedimentary series, resting on the granite of the Mosquito range, and are pierced by porphyry intrusions, as at Leadville. The placer deposits at Fairplay deserve mention, as it was from these that the prospectors spread over the divide to the site of Leadville in 1860.^ 2.09.16. Chaffee County, on the south, contains the iron mines referred to under Example 12d. There are some other gold-bearing veins near Granite and Buena Vista. The lead- silver deposits of the Monarch district are mentioned under Example 30&. In Huerfano County, in the Spanish Peaks, veins of galena, gray copper, etc., are worked to some ex- tent.' 2.09.17. Rio Grande County. In the Summit district are a number of rich gold mines, of which the Little Annie is the best known. The gold occurs in the native state, in quartz on the contact between a rhyolite and trachyte breccia and andesite. The deposits are thought by R. C. Hills to be due to a silicificationof the rhyolite along those lines, probably by the sulphuric acid, which brought the gold. Then the rocks were folded. Oxidation and impoverishment of the upper parts fol- " E, L. Berthoud, "On Rifts of Ice in the Rooks near the Summit of Mount McClellan. " etc. , Amer. Jour. i5.^ >l oc' » , „ < '> '•■is '4 li " 0. o c > 1 ■ Jv Kew Shaft Old Shaft •,-,™gr asd'Level 3jO Le\ el °^, Fig. 105. Fig. 106. Fig. 105. — Cross section of the Bassic Mine, near Rosita. After S. F. Emmons XVII. Ann. Rep. U. S. Oeol. Survey, Part II., p. 434. Fig. 106. — Cross section of the Bull- Domingo Mine, near Silver Cliff, Goto. After S. F. Emmons, X VII. Ann. Rep. U. S. Ceol. Survey, Part IL, p. 442. compare the two chimneys of the Bassick and Bull Domingo with that of the Annie Lee at Victor in the Cripple Creek district Specimens and notes given the writer by E. J. Chibas SILVER AND GOLD. 299 would indicate a similar deposit at the miners of the Darien Gold Mining Company, Cana, Columbia. (See also E. R. Woakes, Amer. Inst. Min. Eng., Atlantic Citj- meeting, Feb- ruary, 1898.) 3.09.21. Humboldt-Pocahontas. This vein is one of sev- eral which have been discovered near Rosita, It is a fissure vein which cut in its upper portion a mass of andesite and andesite breccia, but which at the fourth level, as shown in Fig. 107, forked into several feeders. Above this point it was one of the most regular and clear-cut fissures ever mined in the West. The ore was tetrahedrite in a gangue of barite and TRACHYTE GRANITE BROKEN ZONE POKPHYRT OF PORPHYRT & ANDESITE Fig. 107. — Gross section of the Humboldt- Pocahontas vein, near Rosita, Colo. After S. F. Emmons, XVII. Ann. Rep. U. S. (Jeol. Survey, Part II., p. 42T decomposed wall rock, with which were" associated cbalcopy- rite, pyrite, galena and antimonial sulphides of silver. In the lower levels the vein broke up into several small fissures and troubles, such that operations ceased. 2.09.22. Silver Cliff. At Silver Cliff there is a large flow of porous rhyolite just north of the town, which was early found to be impregnated along small fissures, with chloride of silver and black manganese minerals. For a time free-mill- ing ore was quarried. Later a deep shaft was sunk in the Gey- ser mine, which at 1,850 feet found the faulted contact with the 300 KEMP'S ORE DEPOSITS. Archean gneiss and 200 out into the rhyoliticj tuff a cross-cut encountered a vein that proved productive of rich silver ore. This deep shaft afforded some interesting samples of deep and vadoso waters, which have been analyzed by W. H. Hille- brand, as given in Emmons' paper (see above p. 31). The rhyolite also afforded in the surface workings some extraordi- narily large spherulites which have been described by Cross. Assays of fresh and unaltered samples of the country rocks, which were made for 8. F. Emmons, indicated the presence of silver in five out of nine, viz..: trachyte, 0.007oz. per ton; Fair- view diorite', 0.01 oz. per ton; rhyolite, 0.402 oz. per ton; red granite, 0.005 oz. per ton; black granite, 0.025 oz. per ton; bisilicates of the granite, 0.04 oz. silver per ton, and 0.045 per cent, lead.^ 2.09.24. Teller Coianty. The region of Cripple Creek is the only one of serious importance in this county, but the remarka- ble developments of the last few years have placed it in a very important position. The productive mines are situated in the foothills of Pike's Peak, about ten miles west from the peak itself. The summit is clearly visible from many of them, as are also the peaks of the Sangre de Cristo range, many miles to the south. The town of Cripple Creek lies in the valley of the small stream of the same name, which is a branch of Oil Creek, itself a tributary of the Arkansas River. The valley is an open. and moderately broad upland, but the approaching depressions are narrow defiles, that have presented great diffi- culties to railways. The general country rock of the region is the red granite/ of Pike's Peak. This contains masses of still older mica schists, presumably caught up in its intrusion. The ' R. N. Clark, "Humboldt-Pocahontas Vein,'' Trans. Amer. Inst. Min. Eng., VII., 21. " Si'-'ev Clifif, Colorado,'' Eng. and Min. Jour., Novem- ber 3, 1878, p. 314. W. Cross, "Geology of the Rosita Hills," Proc. Colo. Sci. Soc, 1890, p. 369. Reo. Seventeenth Ann. Rep. U. S. Oeol. Survey, Part 11., 369. Rec. S. F. Emmons, "The Genesis of Certain Ore Depos- its," Trans. Amer. Inst. Min. Eng., XV., 146. Tenth Cmsus, Vol. XIII., p. 80. "The Mines of Custer County, Colo.," Seventeenth Ann. Rep. U. S. Oeol. Survey, Part II., 411. Rec. L. C. Gray bill, "On the Peculiar Features of the Bassick Mine," Trans. Amer. Inst. Min. Eng., XI., p. 110; Eng. and Min. Jonr., October 38, 1883, p. 336. Rec. O. Loew and A. R. Conkling, "Rosita and Vicinity," Wheeler's Survey, 1876, p. 48. See also Stevenson in the Report for 1873, 303 KEMP'S ORE DEPOSITS. schists arfe pre-Cambrian, as are the granites and certain dia- base dikes that occur in the streets of Cripple Creek and on Mineral Hill, but that are of no importance in connection with the ores. At the close of the Eocene or in the Miocene times a small volcanic center broke out in the granite hills now lying east of the town, and perhaps elsewhere. It was marked at first by explosive activity that besprinkled the neighboring region with a breccia made up of fragments of granite and andesite. Later came eruptions of phonolite of one or two varieties that form many dikes associated with the ore bodies. Some minor outcrops of nepheline-syenite and syenite-porphyry are possibly deep-seated and coarsely crystalline representatives of the phonolite magma. Explosive eruptions of this phase seem also to have contributed some phonolite to later breccias. Last of all, dikes of several kinds of basalt, including nepheline basalt, feldspar basalt, and limburgite, closed the eruptive phe- nomena. The breccias, after their formation, became in many cases silicified, so as to produce a very firm rock, and as a rule are so altered that their original rock is to be recognized more by its physical texture than its mineralogy. In areal distribu- tion the breccias are the most prominent rocks near the mines; next follows the granite, while through both are intruded the dikes of phonolite and basalt. The ores are almost entirely productive of gold, for although some little silver often occurs with it, and although lead, zinc and copper minerals are met in one or two mines, the former is of slight economic account and the latter are rareties. Iron pyrites is very widespread, but it is not a great carrier of gold. The real source is the telluride of gold, calaverite, fronx which more or less of the native metal has been derived in the uppor parts of the veins by oxidation. The gangue minerals are quartz, fluorite and decomposed country rock. When the lat- ter is granite, it has lost its mica and often its quartz, leaving a cellular rock more or less impregnated with fresh or decom- posed telluride. The wash of these veins has yielded, some placer diggings, especially on Mineral Hill. The ore deposits are true veins that have been formed along lines of displacement whose amount is, as a rule, slight. The fissures themselves are often insignificant in appearance, but the impregnations of the wall rock with ore to a width of from «SBb**'' H| ^£2— at^,jS4. UMi ^^ ■ 3 H iH 1 1 Fis. 109.— Fietu o/ Cripple Creek, Colorado, from Mineral Hill; Gold Hill in the background. From a photograph by J. F. Kemp, July, 1895. Fig. Wa. — View of Battle Mountain, Victor, Colorado. Fromamndow in Victor. The Portland group of mines is on the left in the background. The Independence mine is on the extreme right. From a photograph by J. F. Kemp, July, 1895. B. & a. 304 KEMP'S OBE DEPOSITS. one to several feet afford very rich and valuable ore bod- ies. The fissures frequently follow the courses of dikes, but are clearly later than, the latter because they cross them, leave them, return to them, and behave in a more or less independent v?ay. Yet the presence of dikes is in a measure a favorable thing, because the dike itself has filled a fissure, and because it, being an offshoot from a larger body of heated rock, and with lines of weakness along the contacts with its walls, doubt- less has often exercised a directing influence on solutions. The y a- / A ^ %^ 7 1 V , ',-1 11 ii \\ \\ Ii t ' / %: / / f t / t / 1 Fig. 113. — Stereogram of the Annie Lee ore-short, Victor, Oolo. After R. A. F. Penrose, XVI. Ann. Rep. TJ. S. Oeol. Survey, Part II., p. 206. accompanying map, from the timely and valuable report of Cross and Penrose, which, with the Pike's Peak Atlas Sheet of the U. S. Geological Survey, should be consulted by all who are especially interested in the region, will give the main fea- tures of the geology. The veins are not large, but they have yielded in the aggregate great amounts of high grade ore. As elsewhere the ores follow shoots in the veins, and the shoots approximate the vertical. Small cross fractures have often exercised an influence upon them. The veins themselves are 8ILVMB AND GOLD. 305 also often in a series of small parallel fissures, rather than in a single one, and impregnate the intervening walls. Ore has been found in blind veins, outside the main lines of deposition, so that frequent cross-cuts are desirable to make sure of the country. The most productive section is on Battle Mountain, just above Victor. The Portland group and the famous Inde- pendence, of which a cut is here reproduced from Penrose's report, are in this hill. Fig. 112 illustrates the Annie Lee ore-body, a very curious one that forms a chimney in a basaltic dike. Bull Mountain, with its spur, Bull Cliff, contains a considerable number around the town of Altman. The fissure on which the Buena Vista, Lee and Victor mines are located is one of the most extended in the district. Raven Hill, Gold Hill, Globe Hill and various minor spurs have also yielded important bodies of ore.' It has been customary to send the ores up to $20 to the ton to tbe stamp mills, for which treatment, however, they are not vv'ell adapted, as the losses are heavj'. Ores from $20 — $40 go to the cyanide mills, and above $40 to the smelters. 2.09.22. Gilpin County has already been mentioned under "Copper" (2 04.08). The general geology of the veins is much like that of Clear Creek, although the ores are quite different. ' W. p. Blake, "The Gold of Cripple Creek," Eng. andMin. Jour., Jan- uary 13, 1894. Whitman Cross, Pike's Peak Atlas Folio of the U. S. Geol. Survey ; to be obtained by sending 35 cents to the Director of the Survey, Washington, D. C. Rec. Whitman Cross and R. A. F. Penrose, Jr., "Geology and Mining Industries of the Cripple Creek District, Colorado," Sixteenth Ann. Rep. of the Director of the U. S. Geol. Survey, 1894-95. Rec. W. F. Hillebvand, "Chemical Composition of Calaverite from Crip- ple Creek," in Cross and Penrose's Report, p. 133. W. H. Hobbs, "Gold- schmidtite, a New Mineral," Amer. Jour. Sci., May, 1899, 357. F. C Knight, "On the Composition of the Cripple Creek Telluride," Proc. Colo. Sci. Joe., October 1, 1894. H. L. McCarn, " Notes on the Geology of the Gold Field of Cripple Creek, Colo.," Science, January 19, 1894, p. 31. R. Pearee, " The Mode of Occurrence of Gold in the Cripple Creek District," Proc. Colo. Sci. Soc, January 8, 1894; Eng. and Min. Jour., March 24, 1894. " Further Notes on Cripple Creek Ores," Proc. Colo. Sci. Soc, April .'i, 1894. S. L. Penfield, "On Calaverite Crystals from Cripple Creek," Cross and Penrose's Report, p. 135. E. Skewes and H. J. Eder, "The Vic- tor Mine, Cripple Creek, Colo.," Eng. and Min. Jour., August 19, 1893, p. 193. E. Skewes, "The Ore Shoots of Cripple Creek," Trans. Amer. Inst. Mm. Eng., September, 1896. G. H. Stone, "The Granitic Breccias of the Cripple Creek Region," Amer. Jour. Sci., January, 1898, 21. 306 KEMP'S ORE DEPOSITS. R. Pearce has shown the existence of bismuth in the ore, and gives reasons for believing that the gold is in combination with it. Clear Creek County contains veins on a great series of jointing planes in gneiss (granite), and in large part replace- ments of the wall. Others are replacements of porphyry dikes or of pegmatite segregations. The ores are chiefly galena, tetrahedrite, zincblende, and pyrite, and the gangue is the wall rock. The curious decrease of value in depth of a series of parallel veins in Mount Marshall was earlier referred to (1.05.05). Georgetown is the principal town and mining center. Others of importance are Idaho Springs and Silver Plume.^ 2.09.23. Boulder County contains veins along joints or faulting planes in gneiss, or granite, or associated with por- phyry dikes, or pegmatite segregations, and carrying tellurides of the precious metals more or less as impregnations of the country rock. The prevalent country rock is called by Emmons a granite-gneiss. Van Diest distinguishes four successive ter^ ranes of massive and schistose rocks along three principal axes and two side ones, and states that the mines are on the sides of the folds. The country is very generally pierced by porphyry dikes, with which the ore bodies are often associated. A large number of species of telluride minerals have been determined from the region, especially by the late Dr. Genth, of Philadel- phia. The mines afford very rich ores, somewhat irregularly distributed.^ ' S. F. Emmons, Tenth Census, Vol. XIII., p. 70. Eec. F. M. Endlich, Hayden's Survey, 18T3, p. 293; 1876, p. 117. P. Fraser, Hayden's Survey, 1869, p. 101. J. D. Hague, Fortieth Parallel Survey, Vol, III., p. 589. Eeo. R. Pearce, Proe. Colo. Sci. Sac., Vol. III., pp. 71, 310. "The Asso- ciation of Gold with Other Metals in the West," Trans. Amer. Inst. Min. Eng., XVIII., 447, 1890. Forbes Rickard, "Notes on the Vein Formation and Mining of Gilpin County, Colo.," Trans. Amer. Inst. Min. Eng., Feb- ruary, 1898. J. J. Stevenson, Wheeler's Survey, Vol. III., p. 3.51. F. L. Vinton, "The Georgetown (Colo.) Mines,' Eng. and Min. Jour., Septem- ber 13, 1879, p. 184. ' Bergrath Burkart, " Ueber das Vorkommon Verschiedener Tellur- Minerale in den Vereinigten Staaten von Nordamerika," Neues Jahrbuch, 1873, 476; April, 493, 1874. 30. Whitman Cross, "A List of Specially Noteworthy Minerals of Colorado," Proe. Colo. Sci. Soo., I., 134, 1884; cites Tellurium, Melonite, Altaite, Hessite, Coloradoite, Sylvanite, Tellurite. A. Filers. "A New Occurrence of the Telluride of Gold and Silver," Trans. Amer. Inst Min. Eng., I., 316, 1872. Red Cloud Mine. S. F. Emmons, SILVER AND GOLD. 307 2.09.35. The resources of the remaining counties of Colo- rado are chiefly in coal. " Sketch of Boulder County," Tenth Census, Vol. XIII., p. 64, 1885. F. JI Endlieh, " Tellurium Ores of Colorado,'' Eng. and Min. Jour.. XVIII, \y,'i, 1874 F. M. Endlieh, " Minerals of Colorado Territory," Hayden's Sara;!/. 1873, 353. J. B. Farish, " Interesting Vein Phenomena in Boulder County, Colo." (Golden Ago Mine), Trans. Amer. Inst. Min. Eng., XIX., 541, 1890, "A Boulder County Mine " {The Golden Age and Sentinel), Proc. Coin. Sol Soo., III., 316, 1890 (same as above). F. A. Genth, " On Tellurides from Red Cloud and Uncle Sam Lodes," Proo. Arner. Phil. Sac, XIV., 235, 1874. "Tellurides from Keystone, Mountain Lion, and John Jay Mines," 7dem, XVII., 115, 1877. J. K. Hallowell, "Boulder County as It Is," Denver, 1883. Worthless. N. P. Hill, "Announces Tellurides at Red Cloud Mine," Amer. Jour. Scl, V., 387, May, 1873. W. F. Hillebrand, "Melonite Forlorn Hope Mine, Boulder County," Proe. Colo. Sci. Soc, I., 133, 1884. E. P. Jennings, "Analyses of Some Tellurium Minerals " (Native Tellurium from John Jay Mine; Sylvanite, Smuggler Mine), Trans. Amer. Inst. Min. Eng., VI., 506, 1877. A. Lakes, "On Boulder County" Geology of Colorado Ore Deposits, c. 1888. A. R. Marvin, " Metamorphic Crystalline Rocks.of the Front Range. " Hayden's Survey, 1873. ' ' On Boulder County, " pp. 144, 147-152, 685. Map. C. L. Palmer, "Eruptive Rocks of Boulder County, Colorado," Proc. Colo. Sci. Soc, III., 380, 1889. C. L. Palmer and Henry Fulton, "The Quartz Porphyry of Flagstaff Hill, Boulder, Colorado," Idem, 351, 1890. R. Pearce, "Remarks on Gold Ores of Rocky Mountains," R. Pearce, In Discussion of Paper by P. H. Van Diest, Proc. Colo. Sci. Soc, IV., 349, 1893. B. Silliman, "Mineral- ogical Notes; Tellurium Ores in Colorado," ^mer. Jotir. Sci.. July, 1874, 3.5-33. Reprinted in Hayden's Report, 1873, 688. J. Alden Smith, quoted by P. H. Van Diest as mentioning Boulder County Mines in his Biennial Report for 1880. P. H. Van Diest, "Notes on Boulder County Veins," Proc. Colo. Sci. Soc, II., 50, 1886. "The Mineral Resources of Boulder County, Colorado," Biennial Rep. State School of Mines, 1886, 25. P. H. Van Diest, ' ' Evidence Bearing on the Formation of Ore Deposits by Lateral Secretion ; The John Jay Mine at Boulder County, Colorado," Proc Colo. Sci. Soc, IV., 340, 18. CHAPTER X. SILVER AND GOLD, CONTINUED. — ROCKY MOUNTAIN REGION, WYOMING, THE BLACK HILLS, MONTANA, AND IDAHO. WYOMING. 2.10.01. Geology.— The southeastern part of Wyoming is in the region of the Great Plains, the southwestern in the Colo- rado Plateau. The Eocky Mountains shade out more or less on leaving Colorado, but are again strongly developed in north- ern Wyoming. The northwestern portion contains the great volcanic district of the National Park, and the northeastern, a part of the Black Hills. The Cretaceous and Tertiary strata chiefly form the plains and plateaus. Granite and gneiss con- stitute the central portion of some of the greater ranges. Pale- ozoic rocks are very subordinate. The resouiies m i.recious metals so far as yet developed are small, consisting cijiefly of gold in quartz veins in the gneisses, schists and granites of Sweetwater County. The great mineral wealth of the State is in coal. The iron mines have already been mentioned (2.03.09), and the copper (2.04.27).' ' H. M. Chance, ' ' Resources of the Black Hills and Big Horn Countxy, Wyoming," Trana. Anier. Inst. Min. Eng., XIX., p. 49. T. B. Comstock, "On the Geology of Western Wyoming," Amer. Jour. Sci., iii., VI., 436. S. F. Emmons, Tenth Cenms, Vol. XIII., p. 86. F. M. Endlich, "The Sweetwater District," Hayden's Survey, 1877, p. 5; "Wind River Range Gold Washings," p. 64. A. Hague, "Geological History of the Yellow- stone National Park,'' Trans. Amer. Inst. Min. Eng., XVI., 783, and Yellowstone Park Folio, U. S. Geol. Surv. See also F. V. Hayden, Amer. Jour. Sci., iii.. III., 10.5, 151. F. V. Hayden, Rep. /or 1870-72, p. 13; also Amer. Jour. Sci., ii., XXXI., 329. A. C. Peale, "Report on the Geology of the Green River District." Hayden's Survey, 1877, p, 511. Raymond's Statistics West of the Rocky Mountains. W. 0. Knight, Bull. U, Wyo. Exp't Station, October, 1893. SILVER AND GOLD, CONTINUED. 309 SOUTH DAKOTA.— THE BLACK HILLS. 2.10.02. Geology.— The, Black Hills lie mostly in South Da- kota. They consist of a somewhat elliptical core of granite and metainorphic rocks, with a ndrth and south axis, and on these are laid down successive strata of Cambrian, Carbonifer- ous, Jura-Trias, and Cretaceous rocks. There are some igne- ous intrusions. The principal product of the Black Hills is gold. The" lead-silver deposits have already been described (3.08.18), and the tin, etc., will be mentioned later.' 6 543 1 22 1345 6 Fig. 113. — Geological section of the Black Hills. After Henry Newton Report on the Black Hills, p. 206. 1. Schists. 2. Granite. 3. Potsdam sandstone. 4. Carboniferous. 5, 6, Jura-Trias. 7. Cretaceous. 2.10.03. The gold occurs in stream placers of Quarternary and recent age, and of no great importance; in supposed, old beach or channel placers in the Cambrian (so-called Potsdam), conglomerates, the "cement" deposits; in impregnations of the ' F. R. Carpenter, "Ore Deposits in the Black Hills," Trans. Amer. Inst. Min. Eng., XVII., 570. Prelim. Rep. on the Oeol. of the Black HiUs. Rapid City, So. Dakota, 1888. W. O. Crosby, •■Geology of the Black Hills," Bost Soc. Nat. Hist., XXIII., p. 89. P. Frazer, "Notes on the Northern Black Hills of South Dakota," r^-fms. Amer. Inst. Min. Eng., XXVII., 304, 1897. John D. Irving, "A Contribution to the Geology and Ore Deposits of the Northern Black Hills, South Dakota," Aniicds N. Y. Acad. Sciences, XII., Part II., }899. Eec. Newton and Jenney, Report on the Black Hills, Washington, 1880. F. C. Smith, "The Occurrence and Behavior of Tellurium in Gold Ores, more particularly vrith Reference to the Potsdam Ores of the Black Hills," Trans. Amer. Inst. Min. Eiiy., XXVI., 485, 1103, 1896. "The Potsdam Gold Ores of the Blacky Hills of South Dakota," Idem., XXVII., 404, 428, 1897. Rec. C. R. Van Hise, "The Pre-Cambrian Rocks of the Black Hills," Bull. Geol. Soc. Amer.. I., 303-244. N. H. Winchell, "Report on the Black Hills," iJep. Clnef. of U. S. Engineers, 1874, Part II., p. 630. The U. S. Geological Survey is preparing a report on the Black Hills, S. F. Emmons and T. A. Jaggar being in charge of the work. 310 KEMP'S ORE DEPOSITS. Cambrian lime-shales, with siliceous gold ores in the neigh- borhood of intruded dikes and sheets of phonolite; in crevices in the heavy Carboniferous limestone, now filled with siliceoup gold ores; and in broad zones or fahlbands of Algonkian slaty and mica schists, carrying auriferous pyrites. The above are l~l — ^ ^ 1 1 S J 1 IV V 1 i 1 \ : . 1 1 1 ; 1 1 . ; 1 1 \\ ; 1 1 K ; I \ ill N i^J^L. l-rJ \ f ^N^-^;i i, CARBONIFEKOUS lIMESTOn PINK UMCSTOlie UAMBAIAH SHAltS , AIGOHKIAN SUTES. tUARniTES ETCl Fig. 114. — Geological section of the strata in the Nortliern Black Hills, S. D. After John D. Irmng, Annals of the New York Academy of Sciences, XIL, Pa/rt II., 1899. found in the northern Hills. In the central portion pegmatites have recently proved gold-bearing. The Quarternary and recent gravels were effective in attracting prospectors in the early days of settlement. They are scarcely worked to-day. The ancient beach gravels are still followed beneath the caps of por- phyry in some small mines in Deadwood Gulch. As described 8ILVEB AND GOLD, CONTINTJED. ;5ii by W. B. Devereux in 1882, the gravels were regarded as hav- ing derived their gold by the beating of the veaves of the Cam- brian Ocean against the auriferous schists described below, but later work has made it probable that they are impregnations like the Potsdam siliceous ores. The pay gravel now runs as a shoot under the later lava sheets. The impregnations of the Cambrian, locally called Potsdalm, lime-shales with tellu- Cambrian Shale and Sandrock. (Very Calcareous) Cambrian Quartzite and Conglomerate ("Cement") Algonkiau Cross Section op Oke Chute. Plan op Oke Chute. The orb is broken awat to show the vebticaiis. Fig. 115. — Plan and, cross-section of a Cambrian, siliceous gold-ore the Black Hills, 8. D. After John D. Trving, Annals N. T. Academy of Sciences, XTL, Part II., 1899. rides and pyrites, constitute a form of ore body that has been of rather recent development, but that is now the leading producer. The mines, as indeed nearly all the gold developments, are in the northern Hills, and are especially abundant around Terry Peak. The Cambrian lies flat, and is penetrated very abun- dantly by dikes and sheets of trachyte and phonolite. The ig- 312 KEMP'S ORE DEPOSITS. neous rocks have themselves sometimes been impregnated, when they lie near an ore body. Associated with the ore shoots and usually bisecting that portion of the floor that lies beneath them are found cracks, called "verticals," that run down to unknown depths, but that are not accompanied by any notable, if, in- deed, by any appreciable faulting; The verticals have di- rected, or have served to introduce the solutions, which have then spread laterally into beds of lime-shales and have replaced +4++^+++ '+ + + + ++ t■+■+■'■■•■^■+■^+++ + +-^■+++^-1-+■■^+■+-^-^++ /UmeBhAntie. Fig. 116. — Plan and section. Mail and ExpresD Mine, to illustrate the siliceous gold ores of the Black Hills, S. D. After John D. Irving, Annals N. T. Academy of Sciences, XII., Part II., \%Q9. the calcareous portion of them with ore and silica. Those beds of lime-shales have proved moat favorable which rest upon a floor of hard quartzite, and this association is so constant that the miners, in regions of phonolite sheets, sink to the quartzite, and then explore for ore. The ore runs in long shoots on the strike of the verticals. The ores contain as gangue quartz, fluorite and the unre- plaeed residue of the lime -shales. The metallic minerals are Fig. 117. — Oreen Mountain. Black Hills, S.D.; a laccolite of phonolite, with the mines of siliceous ore on the so-called "upper contact " around its foot. Photographed by John D. Irving, 1898. Fig. 118. — View of the Union Mine, in siliceous ore, near Terry, in the Black Hills, S. D. Photographed by John D. Irving, 1898. Siliceous Gold Ore IN Limestone. Enlarged Boulder GhowiDg Silicitication o£ Brecciated Limestone and line of demarcation between the Ore and Wall-i-ock Type op Ragged Top Veetical IN Cakbonifeeous Limestone ON Dacy flat Lawrence Co. South Dakota. Fig. 130. — Perspective cross-section of siliceous gold ore in Carboniferous limestone, Dacy Flat, Black Hills. After John D. Irving, Annals N. Y. Academy of Sciences, XII., Part II.. 1899. Fig. 131. — View of the Oolden Star open cut, Lead City, S. D. From a photograph by J. F. Kemp, 1896. SILVER AND GOLD. CONTINUED. 313 pyrite and a supposed telluride of gold, whose presence is indi- cated by analysis, but -which has not been actually seen. Tho- rium has also been detected by F. C. Smith. There are two varieties, red, or oxidized, ores, and blue, or unoxidized. They are collectively known as siliceous or Potsdam ores. The presence of tellurium, of fluorite, and of phonolite is highly suggestive of Cripple Creek, Colo., and of several newer dis- tricts in Montana. At times the vertical may lie alongside of an intruded dike as shown in Fig. 119, and then the ore fol- lows the dike and may impregnate it more or less. The intruded igneous rocks have seldom been able to pierce the heavy cap of Carboniferous limestone, but the laccolites •^,'r -.7:: .r: ±^/. H .-"' M 1 izi: 1.— ^-r- Fig. 119. — Cross-section of a siliceous gold-ore body lying next to a prophyry dike. Black Hills, S. D. After John D. Irving, Annals N. T. Academy of Sbiences. XIL, Part IL, 1899. have served to dome it up, and to fissure it more or less. In the vicinity of the Ragged Top laccolite, on Dacy Flat, these fissures or crevices have been the seat of the deposition of rich, siliceous ores. The ores have replaced and cemented into a hard aggregate, the brecciated limestone that filled the fissure before their introduction. (See Fig, 120.) The older, and formerly the chief source of gold in the Black Hills, is in the great zone or fahlband of schists near Lead City, which carries little lenses and veinlets of quartz, with aurifer- ous pyrites. The pay is thought to lie in the schists. The ores are free-milling, and are controlled by the Homestake Com- pany. They are situated in and near Lead City, in. hills which 314 KEMP'S ORE DEPOSITS. form steep divides between the narrow gulches. The schists strike about N. 20 W., and dip 60 E., and in the Golden Star are stoped out in a cross-section over 450 feet. Porphyry dikes cut the schists, and have spread laterally, so as in their present eroded condition to appear like surface caps of lava. They may have exercised an important influence in the enrichment of the schists, but it seems certain that gold was present in them in the Cambrian times, because the Cambrian sediments when carefully panned almost always afford some trace of the yellow metal. The special local enrichment of the schists may have been influenced by the porphyry. The ores are low grade, run- ning $3 — $4 or less. The Old Abe, Golden Star, Deadwood- Terra and Father de Smet are the chief locations.' In addition to the types of ore body described above, there are found throughout the schists of the Hills occasional quartz veins, of the old so-called "segregated" variety, that have yielded a little gold. Recently pegmatites near Harney Peak have proved productive,' affording ores similar in their geology to those described by Hiissak from Ouro Preto, Brazil,^ and to some in the Transvaal. MONTANA. 2.10.04. Geology. — The eastern part of the State belongs to the region of the Great Plains, which is, however, in portions greatly scarred by erosion, forming the so-called Bad Lands. The approaches to the Rocky Mountains are not abrupt and sudden as in Colorado, but are marked by numbers of outlying ranges of both eruptive and sedimentary rocks. The chain of the Rockies takes a northwesterly trend in Wyoming, and so continues across Montana. It is rather the prolongation of the Wasatch than of the Colorado Mountains, whose strike is for the Black Hills. The character of the ranges is also very dif- ' A. J. Bowie, "Notes on Gold Mill Construction, ' Trans. Amer. Inst. Mill. Eng., X., 87, 1881. W. B. Devereux, "The Occurrence of Gold in the Potsdam Formation," Idem, X., 465; Eng. and Min. Jour., December 23, 1883, p. 334. H. O. Hoffman, "Gold Mining in the Black Hills," Trans. Amer. Inst. Min. Eng. , XVII. , 498 ; also in preliminary report cited under Carpenter, under Geology. See, in addition, references on page 309. " E. Hussak, "Der goldfiihrende, kiesige Quarzlagergang von Passagem in Minas Geraes, Brasilien," Zeits. fiirprakt. Geologie, October, 1898, 345. SILVER AND GOLD, OONTINUED. 315 ferent. They are less elevated, and have broad and well- watered valleys between, that admit of considerable agricul- ture. Geologically the country is in marked contrast with Col- orado. While in the latter the lower Paleozoic is feebly devel- oped, in Montana it is important. Special interest attaches to the Lower Cambrian or perhaps pre-Cambrian quartzites and associated sediments that are present in great thickness in the northwestern part of the State, and along the Idaho line. Fos- sils have recently been reported by C. D. Walcott from a very low horizon. On the east of the Continental Divide the gneisses and schists of the Archean are succeeded by metamor- phosed sediments of the Algonkian, involving 7,000 feet or more, and known as the Cherry Creek formation of the U. S. Geologists. Unconformablj- upon this lies the Belt formation, of 6,000 to 10,000 feet of sediments, which are doubtfully re- ferred to the Algonkian. Still above come the true Cambrian, 1,000 to 1,500 feet; Siluro-Devonian (of which the latter alone is identified by fossils), 200 to 600 feet; Carboniferous limestones, 800 to 1,000 feet, followed by a quartzite and shale series of 200 to 600 feet; Jura-Trias up to 500 feet; and then some thou- sands of feet of Cretaceous and Tertiarj'. Great batholites of granite, in part at least post-Carboniferous, have been intruded as set forth earlier under Butte, 2.04.05. They have basic phases on the margins, and locally, within the masses, as at Butte. The above grouping modifies somewhat the section given in earlier editions of this work, and has resulted from the more repent work of W. H. Weed and A. C. Peale of the U. S. Ge- ological Survey, whose folios should be consulted for local de- tails so far as available. East of the main chain of the Rock- ies there are peculiar isolated groups of mountains of a lac- colite character, such as the Highwoods, the Judith, and the Little Rockies. They rise like huge blisters of sedimentaries, forced up by lenticular sheets of intrusives, and pierced by dikes in vast numbers. They are rocks prevailingly rich in soda, and present many rare and interesting types and some striking parallels with the Black Hills. ^ ' S. Calvin, "Iron Butte: Some Preliminary Notes," Amer. Geol. IV., 95. G. E. Culver, "A Little Known Eegion of Northwestern Montana," Wis. Acad, of Sel, December 30, 1891. W. M. Davis, "The Relation of the Coal of Montana to the Older Rocks," Tenth Census, Vol. XV., p. 697. Rec. 31C KEMP'S ORE DEPOSITS. 2.10.05. Montana took the lead of all the States in 1887 in the production of silver, was second in gold, and first in the total production of the two. It is now second to Colorado in silver, and fourth on the list in gold, but in copper it is first. In its mineral wealth it yields to no other State in the Union. The mining districts are mostly in the western central and western portions. Developments have progressed so rapidly that all the desirable data are not available. 3.10.06. Madison County. The chief product is gold. Near Virginia City the gold-bearing quartz forms veins in schists; in the northeastern part of the county the veins occur in gran- J. Eocles, "On the Mode of Occurrence of Some of the Volcanic Eocks of Montana," Quar. Jour. Geol. Sci., XXXVII,, 399. G. H. Eldridge, "Mon tana Coal Fields,'' Tenth Census, Vol. XV., p. 739. S. F. Emmons, Tenth OeMstts, Vol. XIII., 97. Eeo. Hayden's Survey, Ann. Eep., 1871-72. J. F. Kemp, "On Tellurides in Montana," see The Mineral Industry, YJ., 312, 1898. W. S. Keyes, in Brown's first report on mineral resources, etc., last part, Amer. Jour. Soi., II., 46, 431. Rec. W. Lindgren, "Eruptive Rocks." TenthCensus, Vol. XV., p. 719, forming Appendix B of Davis's first paper. See also Proc. Cal. Acad. Sci., Second Series, Vol. III., p. 39. J. S. Newberry, "Notes on the Surface Geology of the Country Bordering on the Northern Pacific Railroad," Annals JV. Y. Acad. Sci, Vol. III., 242; Amer. Jour. Sci., iii., XXX., 387. "The Great Falls Coal Fields," in Geol. Notes, School of Mines Quarterly, VIII., 327. A. C. Peale, Three Forks Folio, U. S. Geol. Survey, 1896. Rec. F. Rutley, "Microscopic Character of the Vitreous Rocks of Montana,'' Quar. Jour. Geol. Sci., XXXVII., 391. See Eocles, above. CD. Walcott, " Pre-Cambrian Fos- siliferous Formations," Bull Geol. Soc. Amer., X., 199, 1899. Rec. W. H. Weed, "The Cinnabar and Bozeman Coal Fields of Montana," Me??i, II., 349-364 Eng. and Min. Jour., May 14 and 21, 1893. "Montana Coal Fields," Bull. Geol. Soc. Amer., III., 301-330. Livingston Folio, U. S. Geol. Survey. Butte Special Folio, Idem; Little Belt Folio, Idem; BuU Folio (in preparation). Weed and Pirsson, "Highwood Mountains of Montana," Bull. Geol. Soc. Amer., VI., 389, 1895. "The Bearpaw Moun- tains of Montana, Amer. Jour. Sci., May, 1896, 283; June, p. 301; Septem- ber, p. 136; October, p. 188. "Geology of the Little Rocky Mountains,'' Jour. Geol., TV., 399. "The Castle Mountain Mining District," Bulletin 139, U. S. Geol. Survey, 1896. "The Judith Mountains," Ann. Rep. Dir. U. S. Geol. Survey, XVIII., 1899, Part III., 437. . All these are Rec. R. P. Whitfield, "List of Fossils from Central Montana," Tenth Census, Vol. XV., p. 712; Appendix A to Davis's paper. J. E. Wolff, "Notes on the Petrography of the Crazy Mountains," etc., Northern Trans. Survey. " Geology of the Crazy Mountains," Ball. Geol. Soc. Amer., III., 445. H. Wood, "Flathead Coal Basin," Eng. and Min. Jour., July 16, 1892, p. 57. H. R. Wood, "Mineral Zones in Montana," Idem, September 24, 1893, p. 292. SILVER AND GOLD, CONTINUED. 317 ite; at Rochester the gold is associated with galena; at Sheri- dan tetrahedrite and chalcopyrite are found in quartz veins and are rich in gold and silver.'- An interesting vein with tellur- ides has been discovered at the Mayflower mine in the Tobacco Root Mountains.^ It is a fault fissure nearly parallel to the bedding of upturned Cambrian limestones. The ore has re- placed the limestone and is largely oxidized. Placers were of extreme importance in this county in early days, and are still somewhat worked. Alder Gulch, near Virginia City, proved extraordinarily rich. • 2.10.07. Beaverhead County. Near Bannack City quartz veins with auriferous pyrite on the contact between the lime stone and so-called granite. At Glendale, in the northern part of the county, are the Hecla mines, referred to under "Lead- silver" (Example 33). Auriferous (juartz veins are reported farther north." 2.10.08. Jefferson County. There are many varieties of ore bodies in this county, but the commonest type is similar to that at Butte, i.e., veins in granite along fissures of slight displace- ment. The ore is altered country rock, which is mineralized with quartz, pyrite, arsenopyrite and galena. Rich sulphides of silver have been met in the upper portions. The Alta mine near Wickes was located on a vein in andesite. The Ruby mine, on Lowland Creek, appears to be a chimney of boulders of rhyolite, which are coated with gold-bearing silver-sul- phides. It resembles the Bassick mine of Colorado (2.09.20) in geological relations. One of the largest mines yet opened in the county is the Elkhorn. The ore-deposits resemble the "saddles" of the Bendigo Field, Victoria, Australia.* They ' For these notes the writer is especially indebted to Mr. W. H. Weed, of the U. S'. Geological Survey. See also S. F. Emmons, Tenth Census, Xni., 97. The northeastern portion of Madison County has been mapped by A. C. Peale — Three Forks Folio, U. S. Oeol. Survey- -by whom are also given notes on the mines Rec. " E. Pearce, ' ' Notes on the Occurrence of Tellurium in an Oxidized Form in Montana," Proc. Colo. Sci. Soc, November 3, 1896. » S. F. Emmons, Tenth Census, XIII., 97. R. W. Barrell, "The Min- eral Formation at the Golden Leaf Mines," Eng. and Min. Jour., July 17, 1897, 64. * E. J. Dunn, "Quarterly Report to the Mining Department of Victoria, ' December, 1888. T. A. Rickard, " The Bendigo Gold Field," Trans. Amer Inst. Min Eng., XX., 463, 1891. 318 KEMP'S ORE DEPOSITS. occur along the contact of Cambrian slate, and underlying lime- stone, and are replacements of the limestone at the crests of shattered anticlines. The ores are silver sulphides in a quartz gangue, but with occasional large bunches of galena, and very beautiful crystals of calamine/ 3.10.09. Silver Bow County. The mines around Butte are the chief if not the only ones of the county. Their general ge- ology and distribution will be found described under "Copper" — in connection with the copper veins, and a map is there given of the local geology. The silver veins surround the copper ones on the north, southwest and west. Their geological rela- iaS4B 6 1 S '^ Fig. 124. — Cross section af vein at the Alice mine, Butte, Mont. Tlie widtJi of vein is AO feet. After W. P. Blake, Trans. Amer. Inst. Min. Eng., XVI, p. 72. 1. Granite country. 2. Softened granite witli small veins. 3. Olay wall with decomposed granite. 4. Quartz, broken and seamed. 5. Clay and decomposed granite. 6. Quartz and manganese spar — " curly ore." 7, Quartz and ore—" hard veiii." 8. Soft granite with vein- ets. 9. Hard-colored, hard granite of the hanging-v all country. tions and character are much the same, but in mineralogy and distribution they are different. The silver veins occur both in the basic (Butte) granite, and in the acidic (Bluebird) granite. . They contain as gangue in addition to quartz, manganese com- pounds, rhodonite and rhodochrosite. The outcrops of the veins appear as blackened ledges of quartz, the stain being due to manganese oxides. The ores are sulphides of silver, galena, blende and pyrite, with almost no copper minerals whatso- ' The above notes ^vere cliiefly furnished by Mr. W. H. Weed. See also S. F. Emmons. Tenth Census. Vol. XIII., p. 97. J. S. Newberry, "On Red Mountain," Annals N. Y. Acad. Sci., III., p. 2f)l. 'SPA' SKi ■m ^■'" ^nitiaif- Fig. 133. — Outcrop of the Wabash silver lode, projecting above the granite, Butte, Montana. From a photograph by A. C. Beatty, 1896. Kff. . '-r :^^'^. -,'.-fh ._ .:^- :^>->^^:-;^.-^'/c. r^/^ Fig. 123. — Weathered granite, Butte, Montana. The boulders are due to the rounding off of blocks, produced by joints. From a photograph by J. F. Kemp, 1896. SILVER AND GOLD, OONTINVED. 319 ever, except along the border between the copper territory and the silver. The veins display recognizable banding of ore and gangne. One series of locations embracing the Moulton, the Alice and the Magna Charta, has been called the Rainbow lode bj' J. E. Clayton from its erescentic sweep. In other respects, as regards faults, relation to the walls and general origin, the remarks already recorded under "Cop- per" will hold good. Auriferous gravels were early washed in the valley of Silver Bow Creek, and led to the discovery of the deep veins.' 3. 10.10. Broadwater County has recently been organized, and contains quartz veins in slates near Winston, and auriferous pyrites in shattered granite at the Diamond Hill mines. Granite County, formerly a part of Deer Lodge, has important mines near Phillipsburg. The Granite Mountain mine is located on a fissure vein in granite, and yielded rich silver ores, with considerable gold. The vein adjoins sedimentary rocks, which are much metamorphosed by the granite.^ 3.10.11. Deer Lodge County. Placers are numerous along the Deer Lodge River, and auriferous quartz veins are not ' The Butte Special Folio of the U. S. Geological Survey is the best work of reference. It is by W. H. Weed, S. F. Emmons, and Geo. W. Tower. W. P. Blake, "Silver Mining and Milling at Butte, Mont.,'-' Trans. Ainer. Inst. Min. Eng., XVI., 38. "Rainbow Lode, Butte, Mont.," Idem, XVI., 65. Eec. E. G. Brown, "The Ore Dejtosits of Butte City," Idem, XXIV., 543,1894. Eec. S. F. Emmons, "Notes on the Geolo- gy of Butte, Mont.," Idem., XVI., 49. C. W. Goodale, "The Con- centration of Ores in the Butte District, Montana," Idem, XXVI., 599, 1896. Eichard Pearce, "The Associations of Minerals in the Gagnon Vein, Butte City," Trans. Amer. Inst. Min. Eng., XVI., 62. F. D. Peters, Mineral Resources of U. S., 1883-84, p. 374. E. G. Spilsbuiy, "Placer Mining in Montana," Eng. and Min. Jour., September 3, 1887, p. 167. Eec. " Silver Mines of Butte, Mont.," Ibid., Amil 18, 1885, p. 361. Wil- liams and Peters, on Butte, Mont., E^ig. and Min. Jour., March 38, 1885, p. 208. See also references under Butte Copper. ' H. M. Beadle, "The Condition of the Mining Industry in Montana in 1893," Eng. and Min. Jour., February 11, 1893, p. 133. W. H. Dodds, "Granite Mountain Mine," Colliery Engineer, December, 1892. G. W. Goodale and W. A. Akers, "Concentration, etc., with Notes on the Geol- ogy of the Flint Creek Mining District," Trans. Amer. Iiist. Min. Eng., XVIII., 342, 1890. Eeo. "The Granite Mountain Mine," Eng. and Min Jour., December 10, 1887; November 33, 1889. 330 KEMP'S ORE DEPOSITS. lacking. In the extreme eastern part are the veins of the Bald Butte group in slates and intrusive diorite/ 2.10.13. Lewis and Clarke County. The placer mines, near Helena (in Last Chance and Prickly Pear gulches), were the first in the county to attract attention. They were found by the prospectors who spread through the Rocky Mountains as the California gold diggings gave out. Since then many auriferous quartz veins in granite and slates have been devel- oped. Some twenty miles north of Helena, in the town of Marysville, is the Drumlummon group of veins, which carry refractory silver and gold ores, in a quartz gangue, on the con- tact between a diorite boss and the surrounding metamorphic schists. There are also other veins in the granite. Dikes of intrusive rocks occur associated with the ore bodies.^ 3.10.13. Meagher County contains the Castle Mountain min- ing district, once the heaviest producer of silver-lead ores in the State. The Castle Mountains embrace a geological section from and including the Algonkian to the present. Intrusions of granite, diorite, various porphyritic rocks and surface flows of considerable petrographical range are likewise present. In the closing years of the decade of the eighties discoveries were made of silver-lead ores in the Carboniferous limestones, in the neighborhood of intrusions of porphyry and sometimes in the contact zones. After several years of activity, which was maintained despite the remoteness from rail, the low price of silver caused their shutting down. The Cumberland mine, the largest opened, formed a chimney or tubular mass in the lime- stone, and was proved for over 500 feet in depth. Copper- bearing veins were also found in the Belt shales of the Algon- kian in the northern portion of the area.^ In the extreme northern portion of Meagher County, and near the line with Cascade County, the two mining districts of ' R. G. Brown, "Georgetown Mining District," Eng. and Min. Jour., October 13, 1894, 345. E. G. Spilsbury,. "Placer Mining in Montana," Ibid., September 3, 1887, p. 167. ^ J. E. Clayton, "The Drumlunimon Group of Veins,'' etc., Eng. and Min. Jour., August 4 and 11, 1888, pp. 85, 106. 8. F. Emmons, Tenth Census, Vol. XIII., p. 97. L. S. Griswold, "The Geology of Helena, Mont., and Vicinity," Jour, of the Assoc. Eng. Soc, XX., January 1898. ' Weed and Pirsson, "The Castle Mountain District, Montana," Bull 139, U. S. Geol. Survey, 1896. SIL VEB AND GOLD; OONTINUED. 331 Neihart and Barker are located in the Little Belt Mountains, but their outlets are to the north at Great Falls. At Neihart there is a series of fissure veins running north and south, in metamorphic gneisses and schists which are cut by diorite. The veins are narrow and barren in the dark colored gneisses and the diorite, but carry large bodies of galena, with zinc- blende and pyrite in the feldspathic gneiss. The vein filling is replaced and altered country rock with quartz seams in it. The quartz seams in some mines contain much polybasite, pyrargerite and chalcopyrite, carrying very high values in gold and silver. Dikes and larger intrusions of quartz-porphyry also occur, but are unfavorable to the veins , as in them the lat- ter split up and become barren, except within a hundred feet of the surface. At Barker the ores are chiefly silver- bearing galena and occur along the contact between granite-porphyry and limestone.^ 2.10.14. Cascade County contains important coal mines and the smelting center at Great Falls. In Missoula County at Quigley, southeast of Missoula,there is auriferous pyrite in slates of Lower Cambrian or Algonkian age (W. H. Weed). At Iron Mountain operations were formerly carried on, but are now suspended, and there are various minor camps throughout the country.^ ' The latter statement applies as well to Eavalli County in the south. Within the limits of the Lewis and Clarke Timber Re- serve there are occasional intrusions of porphyritic rocks in the Algonkian or Lower Cambrian shales and limestones, and in the neighborhood of the igneous rocks copper deposits are found.^ The Reserve lies in several counties. Similar depos- its are found amid the high peaks of the Continental Divide on the so-called "Roof of the Continent," along the line of Flat- head and Teton counties.* ' The XX. Ann. Rep. of the Director of the TJ. S. Qeol. Survey, which will probably be issued in 1901, will contain a paper by W. H. Weed, on the " Mining Districts of the Little Belt Mountains." The above notes have been kindly furnished by Mr. Weed, in advance of his longer paper. '' F. D. Smith, "The Cedar Creek Placers," Eng. and Min. Jour., Feb- ruary 4, 1899, 143. ' R. H. Chapman, " Geological Structure of the Rooky Mountains with- in the Lewis and Clarke Timber Reserve. " Read at the New York meet- ing, Amer. Inst. Min. Eng., February, 1899. ■• G. E. Culver, ' ' Notes on a little known Region in Northwestern 3ion tana," Trans. Wis. Acad, of Science, Arts and Letters, VIII., 187, 1891. 323 KEMP'S ORE DEPOSITS. 3.10.15. In Flathead County, in the extreme northwestern corner of the State, on Libbey Creek and the Yak Kiver, there have been recently discovered large deposits of gold-bearing pyrrhotite in diorite similar in geological relations to the ores subsequently described at Rossland, B. C. Tellurides were re- ported some years ago at a little camp called Sylvanite. 2.10.16. Choteau and Fergus Counties. Very great scien- tific interest and considerable economic importance areattacJaed to several new districts, that have been opened up in the small outlying groups of mountains, which rise from the plains well to the east of the main chain of the Rocky Mountains. They are all characterized by intrusions of igneous rocks, rich in alkalies, such as syenite-porphyries, phonolites, and related types. These are the rocks which are present in the Black Hills, where, in the Potsdam sandstones, tellurides of gold occur, associated with iiuorite; and at Cripple Creek, Colo., where the ore and gangue are the same. Weed and Pirsson have described the geology of the Little Rocky Mountains. In the central portion of a roughly elliptical area of- upheaval, crystalline Archean schists are seamed by intrusions of granite- porphyry, syenite-porphyry, and, near Landusky, by phonolite, Cambrian, Siluro-Devonian, Carboniferous and Jurassic strata mantle the edges. The ore and gangue are found coating the fragments of decomposed porphyry, but do not seem to lie along well-defined veins.' The parallelism with Cripple Creek is close. The Little Rockies are situated in Choteau County, 180 miles east of the main Rockies. The Judith Mountains, in Fergus County, neaver the central part of the State, are larger, but of much the same geological structure. A core of syenite-por- phj'ry is surrounded by the sediments, which have been up- lifted by its intrusion as a laccolite. It is associated with phonolite. Where the igneous rocks cut the sedimentaries and especially along their contacts with a white Carboniferous limestone free gold and tellurides with associated fluorite are ' W, H. Weed, "Ore Deposits of the Little Rocky Mountains," -Bjigr. and Min. Jour., May 3, 1896, 423. Weed and Pirsson, "Geology of the Little Rocky Mountains," Jour, of Geol., IV., 399, 1896. See also E. S. Dana, in Col. Wni. Ludlow's "Report of a Reconnaissance from Carroll, Montana, to the Yellowstone National Park, " War Dept. , Washington. 1876, 127. SILVER AND GOLD, CONTINUED. 333 found in the brecciated limestone/ Lewiston and Maiden are the chief settlements. The Sweet Grass Hills near the Canadian line in Choteau Countj' are similar in geology and have been the scene of some placer mining. Other groups of mountain, such as the High wood and Bearpaw ranges, which are piles of volcanic lavas and tuffs, are known to contain richly alkaline, igneous rocks, but ore bodies have not yet been reported.^ IDAHO. 2.10.17. (reoiogr?/. —The southern part of the State extends into the alkaline deserts of the Great Basin, and is dry and barren. North of this is the Snake River Valley, which is filled by a great flood of recent basalt, which stretches from the Wj'oming line nearly across the State. North of the Snake River a large area of granite appears in the western portion, and contains many mines. Extensive deposits of gravel also occur. Metamorphic rocks and Paleozoic strata largely consti- tute the northern portion of the State, and are penetrated by many igneous intrusions. The eastern part lies on the western slopes of the Bitter Root Mountains, whose general geology was outlined under Montana. The geology of Idaho has been but slightly studied, and the few reliable records have resulted from the scattered itineraries of Hayden's survey, iso- lated mining reports, and the collections of tbe Tenth Census,^ ' W. M. Courtis, " Gold in Possiliferous Limestone in the Judith Moun- tains," Eng. and Min. Jour., June 38, 1884, 4T8. H. C. Freeman, "The Ammon Mines, Fergus Co. , Mont. , " Idem, May 4, 1895, 416. W. H. Weed, "Mineral Resources of the Judith Mines," Idem. May 33, 1896, 496. Weed and Pirsson, " Geology and Mineral Resources of the Judith Moun- tains," XVIII. Arm. Rep. U. S. Oeol. Survey, Part III., p. 437. ' Weed and Pirsson, " Highwood Mountains of Montana,,'' Bull. Geol. Soc. Amer. ,YI., 389. "Bearpaw Mountains, "^mer. Jour. Sci., May, 1896, 383 ;June, 851; August, 136; September, 188. = G. F. Becker, Tenth Census, Vol. XIII., 53. F. H. Bradley, Hayden's Survey, 1873, p. 308. G. H. Eldredge, "-A Geological Reconnaissance across Idaho," XVI Ann. Rep. Dir. U. S. Geol. Survey. II., 317. F. V. Hayden, Ann. Rep., 1871, pp. 1,147; 1873, p. 30. W. Lindgren, "Mining Districts of the Idaho Basin and the Boise Ridge, Idaho, " XVIII. Rep. Dir U. 8. Geol Survey, Part III., p. 617. Pec. Boise Folio, C7". ,S'. Geol. Survey. Rec. Other folios are in preparation. An extended paper by Lindgren is in press for the XX. Ann. Report of the U. S. Geol. Survey, which will 324 KEMP'S ORE DEPOSITS. but it is DOW receiving vawch attention from tlie U. S. Geologi- cal Survey. 2. 10.18. The extreme northern portion of Idaho has assumed increasing interest in recent years on account of the notable mining developments in the neighboring parts of British Columbia, but discoveries are still larigely in the nature of prospects. Kootenai County forms the so-called "pan-handle," and in it some gold -quartz veins and placers are known. The great silver-lead mines of Coeur d'Alene in Shoshone County have already been described (3.08.23). Some scattered mining camps occur in Talah, Nez Perces and Idaho counties to the south. In the extreme southern tongue of Idaho County is the Sheep Mountain district. The country rock is granite, with associated schists and slates in larger or smaller masses, often as inclusions. There are also dikes of quartz-porphyrites and diorite porphyrites. The ores are impregnations of zones of the schists or slates, with silver-bearing galena, and antimonial and arsenical sulphides.^ 3.10.19. In Lemhi County is the famous old gold diggings at Leesburg, which had a large population in 1859-60, but which are now practically abandoned except for an extensive hydraulic workings at California Bar, further down Napias Creek. In the western side of Lemhi County is Yellow Jacket, with gold ores associated with a complex series of intruded igneous rocks, in metamorphic schists.^ The ores lie along fractured zones and in the Columbia properties are chiefly gold- bearing chalcopyrite. H. H. Armstead, Jr., informs the writer that tellurides have also been detected. In the Yellow Jacket mines the ore is free-milling quartz. In northeastern Lemhi County is Gibbonsville, where auriferous pyrite occurs in quartz veins in slates.^ 3.10.20. Custer County lies south of Lemhi and contains several well-known mines. The Ramshorn is in metamorphic probably be issued in 1901. J. S. Newberry, " Notes on the Geology and Botany along the Northern Pacific Railroad," Annals, N. Y. Acad. Sci., Til. 252. Eaymond's Reports on Mineral Resources West of the Rocky Mountains. O. St. John, Hayden's Survey, 1877, p. 323; 1878, p. 175. ' G. H. Eldredge, XVI. Ann. Hep. U. S. Geol. Survey. Part II., p. 258. ^ G. H. Eldridge, 'A Geological Eeoonnaissance Across Idaho," XVI Ann. Rep. U. S. Geol. Survey, II., 259. " B. MaoDonald, Eng. and Min. Jour., Octobei 3, 1896, 319. Fia. 125. — The old gold diggings on Napias Creek, Leesburg, Idaho, illus- trating an abandoned placer camp. From a photograph by J. F. Kemp, 1896. Fig. 136. — View on Napias CreeTc, below California Bar, Idaho, after a freshet. From a photograph by J. F. Kemp, 1896. SILVER AND GOLD, CONTINUED. 325 slates on a fissure vein that has rich chutes of high-grade sil- ver ores in a siderite gangue. The Custer and the Charles Dickens are farther west, near Bonanza City, and afford both silver and gold in quartz gangue from veins in porphyry. Smelting ores occur in the region, and have been used in some operations based on this treatment. Boise and Elmore coun- ties, on the west and southwest of Custer, contain very impor- tant mining districts. Lindgren has shown the extensive de- velopment of a gray, rather basic granite, baving close affini- ties with the quartz-mica-diorites. It is penetrated by numer- ous dikes of porphyries and minettes and is covered by Tertiary lake beds and effusive rocks. The granite has suffereil consid- erable faulting, usually on a small scale, and in a number of districts the fissures thus formed have been the scene of ore de- position. Their general characters are shown bj' Fig. 127. They may occur as single and isolated fissures, as parallel series, or as lines of crushing with disjointed vein fillings. Quartz is the almost invariable gangue, calcite being very subordinate. The metallic minerals arepyrite, gold, arsenopy- rite, zincblende and galena. These sulphides likewise impreg- nate the wall rock, but they are then low in the precious metals. Silver is invariably present, and in the Banner district in Elmore County, it is the chief source of value. At Atlanta, likewise in Elmore County, the lode is of quite extraordinary size, being known for two and one-half miles, with an a'verage width of sev- enty-five feet, and with man j- spurs. The pay ore occurs in four or five shoots in the main vein, which are of moderate widths. Silver predominates over gold. In the neighborhood of the gold- bearing veins in granite, placers have been and are extensively operated, and indeedj led to the settlement of the countrj'. The principal deep-mining localities are the Idaho City belt, the Quartzburg-Grimes Pass belt, both within the depression known as the Idaho Basin ; and then in the mountains to the west, called the Boise ridge, there are the Neal, Black Hornet, Boise, Shaw Mountain, Willow Creek and Rock Creek districts.' ' J. E. Clayton, "Atlanta District," Trans. Amer. Inst. Min. Eng., VI., 468. G. H. Eldridge, " A Geological Reconnaissance Across Idaho," XVI. Ann. Rep. U. S. Oeol. Survey, 217. W. Lindgren, " Mining Districts of the Idaho Basin and the Boise Ridge, Idaho, " XVIII, Idem, Part III., p. 617. Rec. The Boise Folio, U. S. Oeol. Survey. Rec. An important paper may be expected in the XX Ann. Rep. of the Survey. 326 KEMP'S ORE DEPOSITS. '^4.Hm->'"''"^'' Fig. 137. — Sections to illustrate typical gold veins in the Boise granite region, Idaho. After W. Lindgren, XVIII. Ann. Rep. U. S. Oeol. . U. 8. Oeol. Survey. Part II. , 165. C. E. Dutton, Report on the High Pla- teaus of Utah, Washington, 1880. S. F. Emmons, "Origin of Green River," Science, VI., 19, 1897. Sir. A. Geikie," Archean Rocks of the Wa- satch Mountains," Amer. Jour. Sci., iii., XIX., 363. G. K. Gilbert, "Lake Bonneville," Mijiioqraph I., U. S. Geol. Survey, and IT". Ann. Rep., 169-300 SILVER AND GOLD, CONTINUED. 339 2.11.03. The greater number of the Utah mines are for lead- silver ores, and have been mentioned under "Lead- silver." The northwestern county, Box Elder, is in the alka- line desert region of the Great Basin. The mining districts occur in the central part of the State, in the Wasatch and Oquirrh mountains, and are also found in the extreme south- west. 2.11.03. Ontario Mine. Nearly east of Salt Lake City, in Summit County, is the Ontario mine, a vein from four to twenty -three feet wide (averaging eight feet), in quartzite, but extremely persistent, being opened continuously for 6,000 feet. In the lower working a porphyry dike has come in as one of the walls. It is extensively altered by fumarole action to clay. The best parts of the mine have quartzite walls. The ores consist of galena, gray copper, silver glance, blende, etc. The Ontario vein extends through a number of claims and at least one other important vein is known, the Daly West, which however, has one wall, limestone. Its product and the latter developments on the Ontario have changed the camp to a lead- silver producer.' 3.11.04. The lead-silver veins of Bingham Canon, in Salt Lake County, have already been mentioned. Reference may "The Ancient Outlet of the Great Salt Lake, " Amer. Jour. Sci., ill., XV., 2.56; XIX., 341; see also A. C. Peale, lUd., XV., 439. "The Henry Mountains," Washington, 1877. R. C. Hills. "Types of Past Eruptions in the Rocky Mountains," Proc. Colo. Sci. Sac, IV., 14. International Geo- logical Congress, Washington meeting, 1891, Guide Book to the Rocky Mountains. J. D. Irving, " The Stratigraphical Relations of the Browns' Park Beds, Utah," Trans. N. Y. Acad. Sci., XV., 252. Hague, King, and Emmons, Fortieth Parallel Survey, Vols. I. and II. O. C. Marsh, " On the ■ Geology of the Eastern Uintah Mountains," Amer. Jour. Sci., iij., I., 191. H. Montgomery, "Volcanic Dust in Utah and Colorado," Science, I., 656, 1895. B. Silliman, " Geological and Mineralogical Notes on Some of the Mining Districts of Utah Territory," ^mer. Jour. Sci., in., III., 195. G. O. Smith, " Igneous Phenomena in the Tintic Mountains, Utah," Science, VII., 502, 1898. J. Walther, "The North American Deserts," Nat. Geog. Maguziiie. IV., 163. Wheeler, Gilbert, Lockwood and others, on Western Utah, Wheeler's Survey, Rep. Prog., 1869-71-72. Idem, Final Reports, III. ' T. J. Almy, "History of the Ontario Mine, Park City, Utah," Trans. Amer. Inst. Min. Eng., XVI., 35. "The Ontario Mine," E7ig. and Mm. Jour., May 28, 1881, p. 365. D. B. Huntley, Tenth Census, Vol. XIII., p. 438. H. L. J. Warren, "The, Daly West Mine, Park City, Utah," Eng. and Min. Jour., October, 14, 1899. 330 KEMP'S ORE DEPOSITS. again 'he made to the great bed-veinss of gold quartz associated with them. Ophir CanoD and Dry Canon, in Tooele County, and the Tintic district, in Juab County, have also been de- scribed. In addition to the smelting ores, others have been treated by milling. Quite recently interest has been directed to the mines of the Camp Floyd district, of which Mercur is the chief town. Rich deposits of gold ores, formerly refrac- tory, have yielded to the cyanide process, and have given a new and large lease of life to a district that was abandoned years ago, after having had a short career as a silver producer. Mercur is situated in the southern end of the Oquirrh Moun- tains, in a valley known as Lewiston Carion. A thick series of Carboniferous limestones and very siiborrliDate shales has N-mWh, Fig. SECTION E-E. 128. — Qeological cross- sections at Mercur, Utah, reduced from colored ones by J. E. Spurr; XVt. Ann. Rep. Dir. ir. S. Qeol. Survey, Plate XXVII. The sections cut each other at right angles. been folded into a low anticline, as shown in Fig. 128, whose axial crest is also folded , so that the beds constitute a low dome or swell. One great stratum of limestone has been intruded by an interstratified sheet of quartz -porphyry, locally called the Eagle Hill porphyry, which at the most productive mines has split into three, thin sheets, each 150 feet or less from its neighbor. At some time after the intrusion, ore-bearing circu- lations percolated along the lowest sheet and impregnated the limestone for a zone, usually 10 to 20 feet thick, but reaching even 50 feet or more, with silver-bearing minerals in a gangue of cherty quartz. Where mined the silver was present in thin films of the chloride coating fragments of the chert and lime- SILVER AND QOLB, CONTINUED. 331 stone. -Associated metallic minerals are few. Stibnite is known, and pyrite has been detected with the microscope. Car- bonates of copper have been noted. As gangue minerals cal- QTJAKTZ-PORPHYRY ORB FRESH LIMESTONE (Altered) (Alicrcd limestone) Fig. 139. — Diagram showing relations of ore to fault in 'funnel No. 3, Marion Mine, Mereur, Utah. Scale AQ feet to the inch. After J. E. Spurr, XVI. Ann. Rep. U. 8. Oeol. Survey, 430. sw. Mouth of Tunnel QUABTZ-PORPHYRT (Altered ) ORE (Altered llmoat«**- *-i^VVK~- ■■■■^^:-«5Si ''W^. ' ?ST^'*yrr4:i Fig. 131. — Open cut, showing the pay-streak, at Mercur, Utah. From a photograph by P. K. Hudson, 1898. ■?» Fig. 132.— rhe Golden Gate cyanide mill, Mereur district, Utah. From a photograph by L. E. Biter, Jr., 1898. SILVER AND OOLB, CONTINUED. 333 In Beaver County the interesting deposits of the Horn Sil- ver, the Carbonate, and the Cave ore bodies have been men- tioned under Examples 30gr, 33a, and 336. The iron ore bodies of Iron County will be found under Example 14. In Piute County, near the town of Marysvale, around Mount Baldy, are a number of mines with lead-silver or milling ores in quartz porphyry (copper belt), or between limestone and quartzite (Deer Trail, Green-eyed Monster, etc.). Selenide of mercury is found in the Lucky Boy..' 2.11.05. Example 41. Silver Reef, Utah. Native silver, cerargerite and argentite, impregnating Triassic sandstones, and often replacing organic remains. These deposits were earlier referred to under Example 31, p. 80. They were dis- covered in 1877. At Silver Reef there are two silver-bearing strata or reefs, with beds of shale between. Above the water- .Ore->- Fig. 133. — Two sections of the argentiferous sandstone of Silver Reef, Utah. After I'. M Rolker, Trans. Amer. Inst. Min. Kng.. IX , p. 21. Ore line the ore is horn silver; below it is argentite. At times it replaces plant remains; at other times no visible presence of ore can be noted, although the rock may afford $30 to the ton. The silver always occurs along certain ore channels, distributed through parts of the sandstone. The origin of the deposits has given occasion to a vigorous discussion. J. S. Newberry held that the silver was deposited in and with the sandstone from the Triassic sea, although it may have been concentrated since in the ore channels. F. M. F. Cazin holds that the or- ganic remains were deposited in and with the sandstone, and that these were the immediate precipitating agents of the ores. R.. P. Rothwell explained them much as does Rolker, below. Siii-reij, Vol II., p. 475. J. F. Kemp, " Petrographical Notes on a Suite of Rocks Collected by E. E. Olcott," Trans. N. Y. Acad. Set, XI.. 137, 1893. ' G. J. Brush, " On the Onofrite," etc, Amer. Jour. Sci., iii., XXI., 313. 334 KEMP'S ORE DEPOSITS. C. M. Rolker, who was for some years in charge of several of the mines has also written about them, and is probably nearest to the truth. Rolker argues that the impregnation was subsequent to the formation of the sandstone, ^and was caused by the igneous outbreaks in the neighborhood, and probably runs along old lines of partial weakening or crushing that afterward healed up. Eruptive rocks are known in the neighborhood of the ores both in Utah and in the Nacemiento copper district of New Mexico. From what we know of ore deposits in general this seems most probable.^ jiRIZONA. 2.11.06. Geology.— Arizona lies partly in the plateau re- gion, and partly in the Great Basin. The Basin ranges con- verge with the Rocky Mountains, which, however, are chiefly in New Mexico. The uplands of the ranges are well watered and covered with timber, but the low-lying portion of the Great Basin is an arid desert, and in southwestern Arizona is the hottest part of the United States. Cretaceous and Jura- Trias largely form the plateau region. Running southeast to northwest is the great development of Carboniferous limestone BO often referred to under "Copper," and underlying this are found Archean granites, gneisses, etc. A great series of ore deposits is ranged along this contact. In the southwest are mountains of granites and metamorphic rocks. The Territory also contains vast flows of igneous rocks, and in the plateau country between the converging ranges some 20,000 or 25,000 square miles are covered by them. The Grand Canon of the Colorado has laid bare a magnificent geological section of many thousand feet, from the Archean to the Tertiary.^ ' F. M, F. Cazin, ' ' The Origin of tlie Coppei- and Silver Ores in Triassic Sandrock," Eng. and Min. Jour., December 11, 1880, p. 381 ; April 30, 1881, p. 800. ■' The Silver Sandstone Formation of Silver Reef," Ibkl., May 23, 1880, p. 351; January 10, 17, 34, 1880, pp. 25, 48, 79 (Rothwell). A. W. Jackson, "Silver in Sedimentary Sandstone,'' Rep. Dir. of Mint, 1883, p. 884, reprinted from Cal. Acad. Sei. J. S. Newberry, "Report on the Properties of the Stormont Silver Mining Companj', " etc., Eng. mid Min. Jour., October 38, 1880, p. 369. "The Silver Reef Mines," Ibid. January 1, 1881, p. 4. C. M. "Polker, "The Silver Sandstone District of Utah,'' Trans. Amer. Inst. Min. Eng., IX., 31. ' " Central Arizona," Eng. and Min. Jour., April 33, 1881, p. 385. " Col orado River of the West," review of Ives Expedition, Amet: Jour. Sci.. ii SILVER AND GOLD, CONTINUED. 336 3.11.07. Apache County is in the northeastern corner. In the southern part of the county gold and silver ores, in veins in limestone, associated with copper ores, are reported, and some small placers. 2.11.08. Yavapai County. Gold and silver ores, in quartz veins, in granite and metamorphic rocks. The Black range copper district has alreadj' been referred to under Example 20e. Mohave County. Silver sulphides, arsenides, etc., and alter- ation products in veins in granite, at times shovping agneissoid structure. Only the richest can now be worked. Yuma County. Quartz veins, with silver ores and lead min- erals in metamorphosed rocks (gneiss, slate, etc.), or in gran- ite. Maricopa County contains both Paleozoic and Archean ex- posures. The ore deposits lie mostly along the contact of the two, in granite or highly metamorphosed strata. They are usually quartz veins, with silver ores and copper, lead, and zinc minerals. The Globe district, extending into Pinal County, is the principal one. Mention has already been made of it under "Copper," Example 20c. Pinal County adjoins Maricopa on the south and contains a number of important mines. They produce mostly silver ores, with lead and copper associates, and some blende. The gangue minerals are quartz, calcite, etc., occasionally manganese com- pounds, and sometimes, in the granites, barite. Limestone, slate, sandstone, and quartzite, as well as granite, diabase and diorite, occur as wall rock. 2.11.09. Silver King Mine. A central mass or chimney of quartz, with innumerable radiating veinlets of the same, carry- ing rich silver ores and native silver, in a great dike of feld- XXXIII., 387. G.F. Becker, Tenth Census, Vol. XIII., p. 44. C. E. But- ton, " The Physical Geology of the Grand Canon District," abstract of Monograph II. , Sec. Ann. Rep. Dir. U. S. Geol. Survey, 49-161 ; see also the Monograph. Patrick Hamilton, The Resources of Arizona. A. L. Bancroft & Co., San Francisco, 1884. B. Silliman, "Report on Mining Districts of Arizona, near the Rio Colorado," Eng. and Min. Jour.. August 11, 1877, p. Ill ; taken from Amer. Jour. Sci., ii., XLI., 389. C. D. Wolcott, " Permian and Other Paleozoic Groups of the Kanab Valley, Arizona," Amer. .lour. Sci., iii., XX., 321. " Pre-Carboniferous Strata in the Grand Canon of llie Colorado, Arizona, " Amer. Jour. Sci., December, 1883, 437. Wheeler ; Survey, Vol. III. , and Supplement. 336 KEMP'S ORE DEPOSITS. spar porphyry, with, associated granite, syenite (Blake), por- phyry, gneiss, and slates, all of Archean age. The veinlets ramify through the strongly altered porphyry, and form a stockwork, which furnished the principal ores. In the region are also Paleozoic strata, whose upper limestone beds are re- ferred by Blake to the Carboniferous. The minerals at the mine were native silver, stromeyerite, argentite, sphalerite, galenite, tetrahedrite, bornite, chalcopyrite, pyrite, quartz, calcite, siderite, and, as an abundant gangue, barite. Graham County contains the Clifton copper district, referred to under Example 20a. Cochise County is the southeastern county, and contains the Tombstone district, once the most productive of the precious- metals in the Territory. 2.11.10. Tombstone. A great porphyry dike up to 70 feet thick, faulted and altered, and carrying above the water line in numerous vertical joints, or partings, quartz with free gold, horn silver, and a little pyrite, galenite, and lead carbonate. Curiously enough, in the porphyry itself and far from the quartz veins, flakes and scales of free gold have been found, evidently introduced in solution. Ore also occurs along the side of the dike. There are also other fissures parallel with this principal dike, and still another series crossing these and the axis of the great anticline of the district. Connected with these fissure veins are bedded deposits in the limestone, along the bedding planes or dropping from one to another, appearing to have originated by replacement. Blake offers two explana- tions of the first- mentioned dike deposit— either that the dike; itself held the precious metals, or that the.y came from the pyrite* of the adjoining strata. Several other mining districts of less note occur in the county. The important copper deposits of the Bisbee region have already been mentioned under Example 20/. The most productive mine of the territory for the last year or two has been the Pearce at the town of the same name, but operated by the Commonwealth Co. It is a quartz vein as yet productive of oxidized ores containing silver and gold. 2.11.11. Pima County is the central county of the southern tier, and has Tucson as its principal city. There are numbers of mines of the precious metals, and a few less important copper deposits. SILVER AND GOLD, CONTINUED. 337 Yuma County, in the southwestern corner, has some mines along the Colorado Eiver, on quartz veins in metamorphosed rocks, containing silver and lead minerals/ The Fortuna mine is at present the chief producer. NEVADA. 2.11.12. Geology. — Nevada lies almost entirely in the Great Basin, only the western portion being in the Sierras. The surface is thus largely formed by the dried basins of former great lakes, principally Lakes Lahontan and Bonne- ville. A large number of ranges extend north and south through the State, known collectively as the Basin ranges. They have been formed by block tilting on a grand scale, and present enormously disturbed strata. The geological sections exposed are of surpassing interest (cf. Example 36), and show Archean and Paleozoic in great thickness. In these mountains are found the mining districts, while between them lie the alka- line plains.^ ' G. F. Becker, Tenth Census, Vol. XIII., p. 44. G. H. Birnie, '-Castle Dome District," Wheeler's Survey, 1876, p. 6. W. P. Blake, "The Geology of Tombstone, Arizona," Amer. Inst. Min. Eng., X., 334; Eng. and Min. Jour., June 34, 1882, p. 338; The Silver King Mine, a short monograph. New Haven, March, 1883. Reo. See also Eng. and Min. Jour. , April 28, 1883, p. 338. J. F. Blandy, "The Mining Region around Prescott, Ariz.," Trans. Amer. Inst. Min. Eng., XI., 286; Eng. and Min. Jour., July 31, 1883. "On Tombstone, Arizona," /bid.. May 7, 1881, p. 316; March 18, 1883, p. 145. " Silver in Arizona," General Review, Eng. and Min. Jour., September 31 and 35, 1880, pp. 173, 303. "Central Arizona," Ibid., April 33, 1881, p. 285. O. Loew, "Hualapais District," Wheeler's Survey, 1876, p. 55. B. Silliman, ' ' Report on the Mining District of Arizona near the Rio Colorado," Amer. Jour. Sci., ii., XLI., 389; see also Eng. and Min. Jour., August 11, 1877, p. 111. Raymond's Reports and those of the Di- rector of the Mint contain notes on the Arizona mines. ^ J. Blake, "The Great Basin," Proc. Cat. Acad. Sci., IV., 375; Amer. Jour. Sci. , iii. , VI. , 59. W. P. Blake, ' ' On the Geology and Mines of Ne- vada" (Washoe Silver Region), Quar. Jour. Geol. Sci., Vol. XX., p. 317. H. G. '"'lark, "Aurora, Nevada: A Little of its History, Past and Present," School of Mines Quarterly, III., 133. G. K. Gilbert, "A Theory of the Earthquakes of the Great Basin, with a Practical Application," Amer. Jour. Sci., iii., XXVII., 49. I. C. Russell, "Geology and History of Lake Lahontan, a Quaternary Lake of Northwestern Nevada," Monograph, XL, V. S. Oeol. Survey; also. Third Ann. Rep. Dir. U. S. Geol. Survey, 195. C. D. Wolcott, " Paleontology of the Eureka District," ilfoj/ograp/i 338 KEMP'S ORE DEPOSITS. • 2.11.13. Lincoln County is in the southeastern corner, anJ contains a number of small mining districts. The ores are in general silver-lead ores in limestone, or veins with sulphuret ores in quartzite and granite. Pioche is one of the principal towns, near which is found the once famous and now reopened Raymonfl & Ely mine. A strong fissure cuts Cambrian quartzite and overlj'ing limestone, where the latter has not been eroded, and is occupied by a great porphyry dike. Along the contact between the porphyry and the wall rock the chutes of ore have been found. Mi. Ernest Wiltsee, at the Montreal meeting of the American Institute of Mining Engineers, February, 1893, described and figured the Half Moon mine, on this same great fissure, where the quartzite still retained a limestone cap. The ore-bearing solutions, on reaching a shaly streak containing a limestone layer, departed from the fissure and followed under the limestone, so as to form a lateral enlargement, much like those described and figured from Newman Hill, Colorado, under 2.09.10. The Pahranagat and Tem Pahute districts, still fur- ther south, have had some prominence, but the whole region is so far- from the lines of transportation that the conditions are hard ones.^ 2.11.14. Ney County, next west, has an important mining center, in its northern portion, around the town of Belmont. Quartzites and slates rest on granites in the order named, and in them are veins with quartz gangue and silver chlorides, affording very rich ores. Southeast of Belmont isTybo.^ 2.11.15. White Pine County lies to the northeast, and con- tains the White Pine district. The principal town is Hamilton, about 110 miles south of Elko, on the Central Pacific. The Humboldt range is prolonged southward in some broken hills, consisting chiefly of folded Devonian limestone. At Hamilton these are bent into a prominent anticline, and this has a strong fissure crossing the axis. The geological section is Devonian VIII., U. S. Oeol. Survey. Gilbert, Wheeler, Lockwood, and others, '■ Eastern Nevada : Notes on its Economic Geology,'' Wheeler's Survey, Rep. Prog., 1869, 71, 72; also Vol. III. and Supplement. For further lit- erature, see under Example 36. ' E. P. Howell, Wheeler's Survey, III., 2.57. G. M. Wheeler, Report, Wheeler's Survey, 1869, p. 14. ' S. F. Emmons, Survey of the Fortieth Parallel, Vol. III., p. 393. G. K Gilbert, "On Belmont and Neighborhood," Wheeler's Survey, III., 36. SILVER AND GOLD, CONTINUED. 339 limestone, thin oalcareous shale, thin siliceous limestone, ar- gillaceous shale, probably Carboniferous sandstone, and Carbon- iferous limestone. The ore bodies occur, according to Arnold Hague, in four forms, all in the Devonian limestone: (1) in fissures crossing the anticlinal axis; (2) in contact deposits be- tween the limestones and shales; (3) in beds or chambers in the limestone parallel to the stratification; (4) in irregular vertical and oblique seams across the bedding. The ore is chiefly chloride of silver in quartz gangue. It is thought by Mr. Hague to have probably come up through the main cross fissure, and, meeting the impervious shale, to have spread through the limestone in this vfay.' Egan Cafion is in the northern part of the county, and shoves a geological section of granite, quartzite, and slate in the order named. In slates, and perhaps extending into the quart- zite, is a quartz vein five to eight feet wide, carrying gold and silver ores. Eureka County is the next county v?est of White Pine. The deposits at Eureka have already been described under "Lead- silver." (Example 36.) 3.11.16. Lander County lies next west to Eureka. The Toyabe range runs through it from north to south, and in its southern portion, in Nej' County, contains the Belmont depos- its. (See above, 2.11.14.) At Austin, which is 80 or 90 miles south of the Central Pacific Railroad, now connected with it by a branch, are the mines of the Reese River district, named from the principal stream near by. From Mount Prometheus, which consists of biotite granite or granitite, and which is pierced by a great dike of rhyolite, a western granite spur runs out, known as Lander Hill. The ore bodies are in this hill, and are narrow fissure veins with a general northwest and southeast trend, carrying rich ruby silver ores, with gray cop- per, galena, and blende, in a quartz gangue with associated rhodochrosite and calcite. They are also often faulted. At times they show excellent banded structure. Antimony has recently been found in this region.^ , (See under "Antimony.") ' J. E. Clayton, "The geological structure and mode of occurrence of the silver ores in the White Pine district," Cal. Acad. Sci., IV., 89. .\ Hague, Fortieth Parallel Survey, Vol. III., p. 409. " S. F. Emmons, Fortieth Parallel Survey, Vol. III., p. 849. 340 KEMP'S ORE DEPOSITS. 2.11.17'. Elko County lies north of White Pine and Eureka counties, and contains the Tuscarora mining district. The deposits are high-grade silver ores in veins, in a decomposed hornblende andesite.^ Humboldt County is the middle county of the northern tier, and contains a number of mining disrticts, which produce both silver and gold from quartz veins in the Mesozoic slate. Small amounts of the precious metals come also from Washoe County, in the northwest corner of the State.^ Churchill County adjoins Lander on the west, and pos- sesses a few silver mines. Esmeralda County, in the southwest, has a considerable number of rich silver and gold mines, which produce high- grade ores from veins, with a quarts gangue in metamorphic rocks, slates, schists, etc. (See also under "Nickel.") 2.11.18. Storey and Lyon are two small counties in the western central 'portion of the State, but the former contains the most important and interesting ore deposit in Nevada, if indeed it is not the largest and richest single vein yet discov- ered. 2.11.19. Comstook Lode. A great fissure vein, four miles long, forked into two branches above, along a line of faulting in eruptive rocks of the Tertiary age, and chiefly andesites. In the central part of the. vein the displacement has been about 3,000 feet, shading out, however, at the ends. The ores are high-grade silver and gold ores in quartz, and occur in great bodies, called "bonanzas," along the east vein. Over $325,- 000,000 in gold and silver has been extracted, in the ratio of two of the former to three of the latter. The vein lies on the easterly slope of a northeasterly spur of the Sierras. West of it is Mount Davidson. Theoutcroppings lie on the flank of the latter, about 6,500 feet above the sea and 1,500 below the sum- mit. The general strike of the vein is east of south, and it dips east. Views regarding the geology of the Comstock have changed in the course of years, as they have been influenced by the successive writings of Von Richthofen, King, Church, Becker, and Hague and Iddings, the points in especial controversy being the determinations of the rock species. ' G. F. Becker, Tenth Cunsus, Vol. XIII., p. 34. '' Ibid., p. 33. SILVER AND QoLD, OONTINUED. 311 2.11.20. It may be remarked that the whole scheme of the classification of the volcanic (effusive) rocks rests largely on Von Eichthofen's early studies, and that perhaps the most im- portant generalization of late years is due to the work of Hague and Iddings on the same. Von Richthofen (1865) de- scribed the ore body as filling a fissure on the contact of a so- called syenite, and an eruptive rockthat he called "propylite." The ore and gangue are thought to have been brought up from below by solfataric action, in which fluorine, chlorine, and Flank of Mt.Davidson XX X X ^t ^^tA X X X X X X XXX xx X >; X X X X X x'X xxxxxxx xX xXVXXXXXx X t X X X X X x X X X x-e vxvi^^'^^^xxxxxxxxx xXX '<-^''^^^^%\ xxxxxxv^'^^^^^xxxxxxxx^^^ . R. H. Williams, "The Lake of the Woods District," Idem, July 38, 1894, p. 75. ^ J. T. Donald, "Canada's Newest Gold Field," Eng. and Min. Jour., September 2.-|, 1897, p. 369. 386 KEMP'S ORE DEPOSITS. EECONNAISSAXCE MAP OF A PORTION OF THE TUKON GOLD BELT ^ AND ADJACENT REGIONS IN ALASKA AND PART OF THE NORTHWEST TERRITORY 3cale of Miles 20 IQ 60 1897 , :;,. ;.;.;v,/.:..v;<^-figy^riaSvt* D. H. Browne gives in the School of Mines -Quarterly for July, 1895 p. 297, a very suggestive paper on " Segregation in Ores and Mattes." The 438 KEMP'S ORE DEPOSITS 2.15.16. It is an interesting fact that sperryJite, the unique arsenide of platinum, occurs in the Sudbury region, but was not first discovered in a nickel mine. Traces are, however, said to occur in the nickel ores. Cobalt is in comparatively small amount, much less than in some other nickel regions. The ores vary in richness in different mines and in different parts of the same mine. They run from' over 1% to over 5% nickel, and have a copper percentage somewhat under the nickel. The Worthington has yielded a little gersdorffite (NiAsS), and niccolite (NiAs) in secondary quartz veins, and a vein is reported from Denison toWnship containing both these. A galena vein is reported from the same region, and a little millerite is said to have been found in the Copper Cliff mine. Traces of zincblende have also been noted in some of the ores, but aside from these the mineralogy is limited to the two principal sulphides.^ 2.16.17. Example 49a. Riddle's, Douglass County, Ore- gon. Irregular deposits of hydrated silicates of nickel and magnesia, in serpentine formed by the alteration of peridotites or related rocks. Limonite, chalcedonic quartz and chromite are quite invariable associates, as are clays and other products results of a long experience with mattes show that in the matte pot the copper tends to collect at the top and sides, the nickel in the center. Pai'allels are drawn with the ore bodies, in the central parts of which the nickel is in excess of the copper, while at the edges the copper exceeds the nickel. ' On Sudbury see F. D. Adams, "The Igneous Origin of certain Ore Deposits," General Min. Assoc, Prov. Quebec, January 12, 1894. A. E. Barlow, "The Nickel and Copper Deposits of Sudbury, Ont.,'' Ottawa NaturuUst, June, 1891. E. Bell, Geol. Survey of Can., 1890-91; F. 5, 91. Bull. Oeol. Soc. Amer., II., p. 135. T. G. Bonney, " Notes on a part of the Huronian Series near Sudbury," Quar. Jour. Oeol. Soc, XLIV., 33, 1888. D. N. Browne, Eng. and Min. Jour., September 16 and December 3, 1893. E. R. Bush, "The Sudbury Nickel Region," Idem, March 17, 1894, p. 34.">. F. W. Clarke and C. Catlett, " Platinif erous Nickel Ore from Canada," Amer. Jour. Sol, iii., XXXVII,, 373. J. H. Collins. "Note on the Sud- bury Copper Deposits," Quar. Jour. Geol. Soc, XLIV., 834. J. Garnier, "Mines du Nickel, Cuivre et Platine, du District du Sudbury," Jl!/emoiV«s de la Societie des Ingenieurs Civils., Paris, March, 1891. W. H. Merritt, Trans. Amer. Inst. Min. Eng., XVII,, 395. E. D. Peters, "On Sudbury Ore Deposits," Icie)», October, 1889; Eng. and Min. Jour., October 36, 1889. Berg. u. Hiiett. Zeit., L., 149, 1891. Mineral Resources of the U. S.. 1888, 110. THE LESSBiB METALS, CONTINUED. 439 of alteration. The ore occxirs in loose boulders on the surface, and as a coating on the walls of small cracks and vein lets that penetrate the more massive serpentine. The largest deposits of this character, so far as yet opened in this country, are in the Coast range, soutbvpest of Riddle's Station, Douglass County, Oregon, on the Oregon and California Railroad. The mines occur on a steep hillside, in serpentine that has re- sulted from the alteration of the variety of peridotite, called harzburgite, i.e., bronzite and olivine. Open cuts, small drifts and test pits have served to show the nickel silicates, richest at the outcrop and fading out into small veinlets and reticulations' in depth, until beyond the zone of superficial decay, they disap- pear. The openings are still in the condition of prospects, and productive mining is yet to be begun. The nickel has been shown by J. S. Diller to have been derived from the olivine of the rock, as chemical analysis of this mineral indicated 0.36% NiO By the familiar and ready alteration of the oliv- ine the nickel has separated as the silicate, and has finally been concentrated sufiSciently to be noticeable.' At Webster, in North Carolina, are surface deposits of nickel silicate which have attracted attention. They occur in the variety of perido- tite, which is chiefly olivine, and is called dunite. The geo- logical relations and origin are practically the same as those in Oregon, just cited. The mines are not yet producers." Green crusts of oxidized nickel compounds have been found with the chromite in the town of Texas, Penn., but are of no practical importance. Such superficial discolorations are verj' common in serpentinous districts, but it is a curious fact that they are notably lacking in the dioritic varieties of ExamplelSa. The greatest deposits in serpentines are found in New Cale- donia, in the South Pacific, where they have been mined for some years past, and have furnished in the last decade the largest part of the world's supply. The ores occur, as is the ' F. W. Clarke and J. S. Diller, "Nickel Ores from Riddle's, Webster and New Caledonia," Amer. Jour. Sei., iii., XXXV,, 483. H. B. v. Foullon, "On Riddle's," Jahr. d. k. k. Oeol. Reichsanstalt, 1893, 224. Reo. ' Clarke and Diller, as cited in preceding reference. S. H. Emmens, "The Nickel Deposits of North Carolina," Eng. and Min. Jour., April 30, 1893, p. 476. H. Wurtz, "On the Occurrence of Cobalt and Nickel in Gaston County, North Carolina," Amer. Assoc. Adv. Set., XII., 221; Avwr Jour. Sci., n., XXVII., 24. i40 KEMP'S ORE BEP.OSITB. usual case, associated with serpentine, and along the contact of the serpentine with overlying beds of red clay.' 2.15.18. Example 23a. Mine la Motte. Considerable pyrite occurs with the lead ores mentioned under Example 23, and is separated in the ore-dressing and treated by itself, as it contains nickel and cobalt. Such pyrite is most abundant at Mine la Motte, and considerable matte is made and shipped abroad. Siegenite, a variety of linnseite, is also found im- pregnating a bed of Cambrian sandstone that underlies the lead-bearing dolomite. It is not abundant enough to be of practical importance.^ 2.15.19. Nickel ores have also been reported from Salina County, Arkansas.' Millerite occurs in a vein with quartz gangue in black shales. It is not practically productive. Nickel is also reported in a rather fine conglomerate from Logan Countj', Kansas. It occurs with manganese and limonite in the cementing material of the rock.* Oxidized nickel ores have also been reported at the Lovelock mines, Cburchill Countj-, Nevada, which passed in depth into sul- phides.^ Although they were originally regarded as promising, they have not proved a productive source as yet. At the Gem mine, Colorado, sulphide ores have also been produced. Millerite occurs as an interesting mineral in many other places (St. Louis, Mo. ; with red hematite in Jef5ferson Countj-, New York, etc.), but is only a rarity. Its interesting position at the former locality, in hair-like tufts in the midst of geodes indicates that ' F. Benoit, " Etude sur les Mines de Nickel de la Nouvelle Caledonie,'' Bull, de las Societe de Vlnd. Minerale, VI., 753, IS!)?. J. Gamier, "Me- moire sur les Gisements de Cobalt, de Chrome et de Fer k la Nouvelle Caledonie," Soc. des Ingenieiirs Civils.. 1887. S. Heard, Jr., "New Cale- donia Nickel and Cobalt," Eng. and. Min. Jour., August 11, 1S88, p. 103. D. Levat, Assoc. Frangaise pour T Advanc. des Sci., Paris, 1887. L. Pelaton, "Carte Geologique de la Nouvelle Caledonie," Genie civile, 1891. ' J. M. Neill, " Notes on the Treatment of Nickel and Cobalt Mattes at Mine la Motte," Trans: Ainer. Inst. Min. Eng., XIII , 684. For aJiditional literature see under 2.05.09. ' Ark. Geol. Survey, 1888, Vol. I., pp. 34, 35. ' F. P. Dewey, " On the Nickel Ores of Russell Springs, Logan County, Kansas," Trans. Anier. Inst. Min. Eng., XVII., 636. ' A. t). Hodges, " Notes on the Occurrence of Nickel and Cobalt Ores in Nevada " Trans. Ainer. Inst. Min. Eng., X., 657. S. B. Newberry, "Nickel Ores from Nevada," Amer. Jour. Sei., iii.; XXVIII,, 123. THE LESSER METALS, CONTINUED. 441 nickeliferous solutions must have circulated rather widely in these limestones. In Jefferson County it probably resulted from the decaying pyritous mineral to which Smyth refers the iron ore, as outlined earlier. PLATINirM. 2.16.a0. Some hundreds of ounces of platinum are annually gathered from placer washings in northern California, and two or three times as much more from British Columbia. Much iridium and osmium are associated with it. In October, 1889, F. L. Sperry, the chemist of the Canadian Copper Company, of Sudbury, discovered a heavy crystalline powder in the con- centrates of a small gold-quartz mine in the district of Algoma. He detected the presence of platinum, and sent the material to Professors Wells and Penfield, of Yale, by whom it was ana- lyzed and crystallographically determined to be the arsenide of platinum, PtAsz, the first compound of platinum, other than an alloy, detected in nature. It has been appropriately named sperrylite by Wells, and although not at present a source of platinum, it may merit attention, as the price of the metal has sometimes approximated that of gold. The chief reliance of the world for platinum is Eussia, whose deposits are in the Urals. More or less comes also from Colombia, South America, and from placer washings elsewhere. Serpentine is very generallj' its mother-rock.^ TIN. 2.15.21. Ores: Cassiterite, SnO^, Sn. 78.67, 0. 21.33. The sulphide stannite is a rather rare mineral. ' California: Eng. and Min. Jour., June 29, 1889, 587. B. Silliman, " Cherokee Gold Washings, California," Amer. Jour. Sci., iii., VI., 133. Canada: F. W. Clarke and Ch. Catlett, " Platiniferous Nickel Ore from Canada," Amer. Jour. Sci . iii., XXXVII., 372. H. L. Wells and S. L. Penfield, "Sperrylite, a Ne\c Mineral," Idem, iii., XXXVII., 67. Eussia: A. Daubree, "On the Platiniferous Rooks of the Urals," Trans. French Acad. Sci., March, 1S75; Amer. Jour. Sci., iii., IX., 470. General paper by C. BuUman, Ths Mineral Industry for ISSH, p. 373. Rec. " An elaborate x-eview of the tin mines of the world by C. M. Roelker will be found in the XVI. Ann. Rep. of the Director of the V. 8. Geol. Survey, Part III., pp. 458-538, 1895. E. Eeyer has given a general dis- cussion in "Zinn,' eine geologisch-montanistisch-historische Monographic, " Berlin, 1881. A general, genetic discussion is given by J. H. L. Vogt, "Die Zinnstein gang-gruppe," Ze.it^. fiir prald. Geol.. 1895, 145. 443 , , KEMP'S ORE DEPOSITS. Cassiterite occurs in small stringers and veins on the borders of granite knobs or bosses, either in the granite itself or in the adjacent rocks, in such relations, that it is doubtless the result of fumarole action consequent on the intrusion of the granite. It appears that the tin oxide has probably been formed from the fluoride. A favorite rock for the ore is the so-called greisen, a mixture of quartz and muscovite or litbia mica, and probably an original granite altered by fumarole action. Topaz, tourmaline, and fluorite are found with the cassiterite, and indicate fluoric and boracic fumaroles. Wolframite, schee- lite, zinnwaldite and one or two other minerals are character- istic associates. Cassiterite seems also to crystallize out of a granite magma with the other component minerals. Cassite- FlG. 163. — Horizontal section of the Etta granitic knob, Black EUls, 8. D. After W. P. Blake. Mineral liesoiivces, 1884, p. 603. rite, being a very heavy mineral, accumulates in stream gravels, like placer gold, affording thus the stream tin. When . of concentric structure the ore is called wood tin. It is not yet demonstrated that the United States have workable tm mines. 3.15.22. Example 51. Black Hills. Cassiterite disseminated in masses of albite and mica and associated with immense crystals of spodumene, which are contained in knobs of granitic rock. Columbite, tantalite, and beryl are also found. There are two granite knobs which are best known, the Etta and the Ingersoll. The former is a conical hill, which pierces mica and garnetiferous slates and which is 250 feet high by 150 feet by 200 feet. Tunnels show it to have a concentric structure — ^first, THE LESSER METALS, CONTINUED. 443 a zone of mica; second, a zone of great spodumene crystals, with an albitic, so-called greisen which carries cassiterite in its interstices; lastly, a mixture of quartz and feldspar as a core. Other tin-bearing granites occur as dikes, or veins, as much as 80 feet wide, and bearing the so-called greisen and tin ore in quartz. They are called segregated veins by Carpenter, who doubts their true igneous character, probably on good ground. No tin is yet commercially produced. The tin deposits extend also into Wyoming.^ 2.15.2.3. Pebbles of stream tin have been found in gold washings in Montana and Idaho. Tin is also known in the Temescal Mountains, southern California. The area has re- cently been described by H. W. Fairbanks, who summarizes the geological relations as follows : "A semi-circular area of granite, over two miles in diameter, surrounded on the north- west and south by porphyries, and joined on the east to a great body of granitic rocks extending indefinitely in that direction. Around the border of this granite protuberance are many dikes of a fine-grained granite. Cutting through the granite in a northeast and southwest direction are black tourmaline veins, which form the gangue of the tin pre when it is present." While tourmaline is a common associate of tin ores, this great abundance of it is unusual. The ore occurs as a yellow, un- crj'stalline variety, in layers, and as a brown, granular, mas- sive form, or in brown crystals. The ore and veinstone seem to have replaced the usual minerals of the granite, doubtless by fumarole action along fissures. The mining proved unsuccess- f ul after a serious attempt.^ ' W. P. Blake, Mineral Resources. 1883-84, p. 603. Reo. Amer. Jour. Set, September, 1883, p. 235; Eng. and Min. Jour., September 8, 1886. "Tin Ore Deposits of the Black Hills," Trans. Amer. Inst. Min. Eng., XIII., 691'. F. R. Carpenter, Prelim. Rep. Dak. School of Mines," 1888; also Trans. Amer. Inst. Min. Eng., XVII., Tud. "Tin in the Black Hills," Eng. and Min. Jour., November 38, 1884, .p. 358. Mineral Resources of the U. S., annually under "Tin." W. P. Headden, "Notes on the Dis- covery and Occurrence of Tin Ore in the Black Hills,'' Colo. Sci. Soc., III., 347. A. J. Morse, "Harney Peak Tin Mines,'' Eng. and Min. Jour., November 17, 1894,' p. 463. ° W. P. Blake, ' ' Occurrence of Wood Tin in California, Idaho, and Mon- tana," Min. and Sci. Press, San Francisco, Augusts, 1882. H. W. Fair- banks, "The Temescal Tin District," Eleventh Rep. Cat. Stati' Mineral ' ogist, 1893. pp. l'il-114. A fuller paper will be found in the Amer. Jour. Sci., July, 1897, 39. H. G. Hanks, Rep. Cal. State Mineralogist, 1884, p. 121. 444 KEMP'S ORE DEPOSITS. 2.15.34. Narrow veins carrying oassiterite have been ex- ploited in the granite and schistose rocks of Rockbridge and Nelson counties, Virginia, in North Carolina, and in Alabama. Companies have been formed to work the two former, but as yet without a notable output.^ 2.15.35. Cassiterite has been discovered in narrow veins in mica schists with lepidolite and fluorite at Winslow, Me., and is known at other places in Maine and New Hannpphire. A salted tin prospect several years ago spread the impression that tin was to be found in Missouri.^ Narrow quartz veins have been recently discovered near El Paso, Tex., with cassiterite richly disseminated through them. 3.15.36. Mexico. Tin ores occur in a great number of places in Mexico, and small amounts of tin have been pro- duced during and since the time of the Aztecs. W. R. Ingalls has carefully described the deposits in the State of Durango, and has shown that those at Potrillos are in veinlets or small veins in rhyolitic tuffs, with associated topaz, chalcedony and hyalite. The cassiterite is in irregular bunches and nodules, but as in practically all the Mexican mines, the amount is too small to be the basis of extended mining. Alluvial gravels were earlier worked but have been long since exhausted. At Cacaria, likewise in Durango, the wall rock is described as quartz-porphyry, but near the city of Durango, and at Sain Alto, Zacatecas, the rhyolite tuffs are again the country rock.^ The tin of Durango runs high in antimony. ' H. D. Campbell, " Tin Ore, Cassiterite, in the Blue Ridge in Virginia,' The Virginias, October, 1883. A. R. Ledoux, "Tin in Nortli Carolina,'' Eng. and Min. Jour., December 14, 1889, p. 521; see also February, iss;, p. 111. McCreatli and Piatt, Bull. Iron and Steel Assoc, November T, 1883, p. 209. W. Robertson, London Min. Jour.. October 18, 1884- A. Winslow, "Tin Ore in Virginia," Eng. and Min Jour., Novemb:^r, 188.5, Rec. = W. P. Blake, Mineral Resources. 1884, p. .538. C. H. Hitchcock, "Discovery of Tia Ore and Emery at "Winslow, Me.," Enq. a'ld Min. Jour., October 3, 1880, p. 218. T. S. Hunt, "Remarks on the Occurrence of Tin Ore at Winslow, Me.," Trans. Amer. Inst. Min. Eng., I.. 573. C. T. Jackson, "Tin Ore at Winslow, Me.," Proc. Bast. Soc. Nat. Hint.. XII., 2(i7. " F. A. Genth, "On the Cacaria Ores," Proc. Amcr. Philo. Soc, XXIV., 1887, p. 38. W. R. Ingalls. "The Tin Deposits of Durango," Tranfi. Amer. Inst. Min. Eng., XXV., 146. C. W, Kempton, "Note on Tin Ores at Sain Alto, Zacatecas,'' Idem, 997. CHAPTER XVL CONCLUDING REMARKS. 2.16.01. In review of the western border of the country, we note the elevated plateau rising from the Mississippi to the Rocky Mountain system, which consists of various ranges of general north and south or northwest and southeast trend, with broad valleys between. To the west the Colorado Plateau is met, and then the Wasatch Mountains and the Great Basin, with its various, subordinate, north and south ranges. These are succeeded by the Sierra Nevada, and the great valley of Cali- fornia, the Coast range, and finally the Pacific Ocean. From the Archean to the close of the Carboniferous there were granitic islands around which active sedimentation pro- ceeded. At the close of the Carboniferous the elevation of the Wasatch and the region of eastern Nevada occurred. At the close of the Jurassic the elevation of the Sierra Nevada took place. The chief upheaval of the Rocky Mountain system came at the close of the Cretaceous and that of the Coast range at the close of the Miocene Tertiary. Smaller and less impor- tant oscillations have occurred before and since. Each eleva- tion was accompanied by foldings, faultings, and extensive outpourings of eruptive rocks. The resultant fractures and the circulation of hot and chemically active solutions, occasioned by the dying volcanic activity, constitute the primary cause of the formation of the ore deposits, which in some ca"ses lie in ranges along the lines of faulting or of disturbances, and in others are irregularly scattered. We may recognize the Coast range belt with mercury and chromium ; the California gold belt in the western Sierras; the silver belt of Utah on the west- ern flank of the Wasatch; a belt in Arizona from southeast to northwest, along the contact between Paleozoic limestone, 446 KEMP'S ORB DEPOSITS. mostly CarboDiferous, and the Archean ; and the great str^ Lch of lead-silver mines in the Carboniferous limestones of Colo- rado. The other areas are scattered, and apparently exhibit no such grand general relations to these geographical and geo- logical phenomena/ 3.16.02. In the Mississippi Valley, W. P. Jenney has re- marked the connection of the antimony and silver deposits of Arkansas with the Ouachita uplift that traverses that State and Indian Territory; the location of the Missouri lead and zinc ores along the Ozark uplift; and he has referred the Wisconsin lead and zinc mines, as well as those in the neigh- boring parts of Iowa and Illinois, to an uplift south of the Archean area of Wisconsin. The limitation of the Lake Superior copper deposits to the Keweenawan system may be mentioned, and such parallelism as prevails among the Lake Superior iron ores. In the East the great belt of Clinton ores; the long succession of Siluro-Cambrian limonites in the Great Valley; the black-band ores and' clay-ironstones of the Carbon- iferous; the closely similar geological relations of non-titanifer- ous, magnetite lenses in the Archean gneisses; and the general association of titan iferous magnetites with rocks of the gabbro family the country over — all are striking illustrations of broad, general geological features that may characterize extended series of ore deposits. To these may be appended the great series of pyritous veins in the slates and schists of the East, the gold belt of the Southeastern States, and the small copper de- posits associated with the Triassic traps and sandstones. Aside from the groups mentioned, while there are important mines not included in the list, the others do not exhibit the same wide- spread uniformities of structure or associations." Yet, from the ' G. F. Becker, Amer. Jour. Sei., Third Series, Vol. XXIII., 1884, p 209. W. P. Blake, Eep. Cal. State Board of Agriculture, 1866. S. F, Emmons, " The Structural Relations of Ore Deposits," Trans. Amer. Inst. Min. Eng., XYl., 804. E. W. Raymond, "Geographical Distribution of Mining Districts in the United States," Idem, I., 33. Fortieth Parallel Survey, Vol. III., Chapter I. " Precious Metals," Tenth Census, Vol. XII. ' It is only proper in this connection to refer to the paper by T. F. Van Wagenen, on "System in the Location of Mining Districts," School of Muies Quarterly, January, 1898, p. 189. The author regards the location of the veins and the mining districts as having been determined hy the lines of terrestrial, magnetic currents, which converge at the magnetic CONCLUDING REMARKS. 447 list cited, it forcibly appears tbat similar conditions have brought about related ore bodies over great stretches of country ; and while in the opening schemes of classification points of difference were emphasized, in the closing pages points of re- semblance may be with equal right brought to the foreground. 3 16.03. A few general conclusions suggest themselves from the preceding pages. (1) The extreme irregularity in the shape of metalliferous deposits, and from this the unwisdom of the United States law in the West, which is based on well-defined fissure veins. The only practicable method is that a man should own all that is embraced in his property lines, whether the ore body out- crops outside or not. "A square location is the square thing" (Raymond). (3) The very general proximity of eruptive rocks in some form to the ore bodies. Except in the case of iron, there are only a few where these are not present, and apparently strong factors in the circulations which formed the ore. The lead and zinc deposits of eastern and western Missouri and the neighbor- ing States, and of New York and Virginia, are almost the only ones, and we are justified in concluding that eruptive rocks are of great importance. (3) We know from the investigations of Sandberger and others that the dark silicates of many rocks contain percentages of the common metals. The choice is open whether to refer the ore to original disseminations in these, and to derive it by gradual concentration, probably at great depths, or to some indefinite unknown source, which can only be described as "below." pole of the earth. They therefore are independent of the great lines of mountain making and igneous outbreaks. The latter are, however, re- garded by the present writer as of paramount importance. See above paragraph. APPENDIX I. In the following pages the principal schemes of classification of ore deposits are grouped according to certain relationships and similarities that run through them. It would be interest- ing to arrange them in chronological order, but points of like- ness and unlikeness would not thus be brought out, nor can the influence of one writer on another be so clearly emphasized. • The underlying object, aside from showing in a bird's-eye view what has been done, is to lead up to the purely genetic class- ification which appears in Chapter VI, Part I., and which would properly come in after No. 16. In the earlier editions of the book it was so placed, and all the schemes formed part of Chapter VI, but so many have appeared in later years that it has seemed wiser not to overload the main text with matter that is largely a subject of reference, and that can be treated with greater freedom in an appendix. The importance of the genetic principle has been more and more appreciated in recent years, and it is a striking fact that the more weighty recent contributions on ore deposits have been dominated by it. In reading this appendix it should be further appreciated that the schemes were originally grouped so as to lead up to the one on page 56 as a climax, and that in it mere form is eliminated to the last degree, and well-recognized geological phenomena are brought to the foreground. It has indeed been said with force that the origin of ore deposits is a subject which is very largely a matter of hypothesis, and that it involves profound subter- ranean causes, of which we know but little. Still, it is held that an acquaintance with what has been accomplished in re- cent years by our best workers, and a rigid adherence to well- recognized principles in geology and mineralogy, especially as developed in rock study {i.e., in that department of geology that of late years we have grown to call petrology), will APPENDIX I. 449 establish much that cannot be questioned, and will aid in differentiating the cases which are still objects of reasonable doubt. It is, however, true that among the subjects on which human imagination, often superstitious, has run to wild ex- tremes, and on which cranky dreamers have exercised their wits, the origin of ore deposits stands out in particularly strong relief. A. Schemes Involving only the Classification of Veins, (1) G. A. von Weissenbach/ Gangstudien, 1850, p. 12. (a) Sedimentargange (Sedimentary Veins). (&) Kontritionsgange (Attrition Veins). (c) Stalactitische oder Infiltrationsgange (Stalactitic or Infiltration Veins). (d) Plutonische oder Gebirgsmassengange (Masses, dikes, knobs, bosses, etc., not necessarily with ores). (e) Ausscheidungsgange (Segregated Veins), {f) Erzgange (True or Fissure Veins). (2) B, von Cotta, in comments on Von Weissenbach's Scheme. Gangstudien, 1850, p. 79. According to the vein filling. 1. Qesteinsgange (Dikes). (a) Not crystalline (Sandstone). {b) Crystalline (Granite). 3. Mineralgange (Veins). (a) Of one non-metallic mineral. (6) Of several non-metallic minerals. 3. Erzgange. Ore veins. (3) B„ von Cotta, Idem, p. 80. According to Shape and Position. I. Wahre, einfache Spaltengange (Fissures), (a) Qiierdurchsetzende (Cross fissures). (6) Lagergauge (Bed veins), (c) Kliiftfi (Cracks), Adern (Veinlets). » See also Whitney's Metallic Wealth of the U. S., 1854, p. 44. 450 KEMP'S ORE DEPOSITS. II. Gangziige (Linked Veins).' III. Netzgange (Reticulated A'eins). IV. Contaktgange (Contact Veins). V. Lenticulargange (Lenses). VI. Stockformige Gange (Stocks, Masses). (4) B. von Cotta, Idem, p. 80. According to the texture of the vein filling. I. Dichte Gange (Compact' Veins). II. Krystallinische Gange. III. Krystallinisch, kornige (granular) Gange. IV. Krystallinisch, massige (massive) Gange. V. Gange mit Lagentextur (Banded veins). (a) Ohne Symmetric der Lagen (unsymmetrical). (6) Mit Symmetric der Lagen (symmetrical). VI, Gange mit Breccien oder Conglomerattextur. (5) J. Le Conte, Amer. Jour. Sci., July, 1883, p. 17. 1. Fissure Veins. 2. Incipient Fissures, or Irregular Veins. 3. Brecciated Veins. 4. Substitution Veins. 5. Contact Veins. 6. Irregular Ore Deposits. In von Weissenbach's table the sedimentary veins are much the same as the "sandstones dikes" which J. S. Diller has recently described. {Bull. Geol. Soc. Amer., I., 411.) They and the stalactitic veins have small practical value, although of great scientific interest, itnder (d), the stookworks with tin ores are the principal illustration of eco- nomic prominence. The attrition veins are an important class, and increasing study has widened the application of this or ' Gangziige is happily translated "linked veins," by Dr. G, F. Becker {Quicksilver Deposits, p. 410). Any attempt to render the original by preserving the figure of a flock of birds or of a school of flsh, etc., is, as Mr. Becker remarks, infelicitous, if not impossible. APPENDIX I. 461 synonymous terms. Segregated veins and true veins are well- known forms. In the comments of von Cotta, which follow von Weissenbach's paper, veins are grouped from every possi- ble standpoint, von Weissenbach's scheme being taken as the one based on origin, Nos. 2 and 4 have small claims to atten- tion. No. 3 foreshadows the drift of many subsequent writers. The meanings of the terms are self-evident, except perhaps Gangzuge (linked veins). This refers to a group of parallel and more or less overlapping veins, deposited ajong a series of opening, evidently of common origin. It is a convenient term. The terms used by Le Conte may be passed without comment as being self-evident in their meaning, except (4) and (6). The scheme was devised, as a perusal of the citation will show, after the author had set forth some original views of the causes which lead to the precipitation of ores, and had forcibly stated others very generally accepted. In the explanatory text some quite curious associations are found, which are cited by way of illustration. Thus, under group (4), stalactites, caves, gash veins, and the Lead vi He ore bodies are considered examples, and under group (6) the grouping together of beds, igneous masses, and all other forms of so-called irregular deposit is decidedly open to criticism. This is the more emphatic be- cause the concluding sentences of the paper (of whose general value and excellence there can be no question) give the impres- sion that the author felt he had cleared up all the points in the origin of ore bodies which would be of interest or importance to a purely scientific investigator as contrasted with a practical miner. B. General Schemes Based on Form. (6) Von Cotta and Prime. Ore Deposits, New York, 1870. I. Regular Deposits. A. Beds. B. Veins. (a) True (Fissure) Veins. (6) Bedded Veins. (c) Contact Veins. (d) Lenticular Veins. 452 KEMP'S ORE DEPOSITS. II. Irregular Deposits. C. Segregations. (a) Recumbent. (6) Vertical. D. Impregnations (Disseminations)^ (V) Lottner-Serlo, Leitfaden zur Bergbaukunde, 1869. I. Eingelagerte Lagerstatten (Inclosed Deposits). A. Plattenformige (Tabular). (a) Gauge (Veins). (&) Flotze und Lager (Strata, beds, seams). B. Massige Lagerstatten (Massive Deposits.) (a) Stocke I Mac^^ec; (b) Stockwerke j ^^^^^ses. C. Andere unrege.lmassige Lagerstatten (other ii*' regular deposits), (a) Nester (Pockets). (6) Putzen. (c) Nieren (Kidneys). II. Aufgelagerte Lagerstatten (Superficial Deposits). D. Triimmerlagerstatten (Placers). E. Oberflachliche Lager (Surface beds). (8) Koehler, Lehrbuch der Bergbaukunde, 1887. I. Pla'ttenformige Lagerstatten (Tabular Deposits). (o) Gauge (Veins). (6) Flotze und Lager (Strata, beds, seams). II. Lagerstatten von unregelmassige Form (Deposits of irregular Form), (a) Stocke und Stockwerke (Masses). (6) Butzen, Nester, und Nieren (Pockets, concre tions, etc.). (9) Gallon, Lectures on Mining, 1886 (Foster and Galloway's translation). I. Veins. II. Beds. III. Masses {i.e., not relatively long, broad, and thin). APPENDIX I. 453 The scheme of von Cotta and Prime carries out the principle of form to its logical and some\^'hat trivial conclusion. Thus under irregular deposits it is a matter of extremely small classificatory moment whether an ore body is recumbent or vertical. Otherwise the scheme is excellent, and its influence can be traced through most of those that are of later date. The original draft came out in the German in 1869. All the others are ftom treatises on mining, in which this subject plays a minor role, and indicates the tendency, referred to above, of mining engineers, when writing theoretically, to imagine cer- tain fairly definite forms, which are to be exploited. As previ- ously remarked, however, considering the uncertainty . of ore bodies and their variability in shape, it is here argued that the genetic principle might better take precedence. Several of the German terms are difiScult to render into English mining idioms, as for example, Stock, Butzen (Putzen), Neater, and Nieren. C. Schemes, Partly Based on Form, Partly on, Origin. (10) J. D. Whitney, Metallic Wealth of theUnited States.^ 1854. I. Superficial. II. Stratified. (a) Constituting the mass of a bed or stratified de- posit. (6) Disseminated through sedimentary beds, (c) Originally deposited from aqueous solution, but since metamorphosed. III. Unstratified. A. Irregular. («)• Masses of eruptive origin. (6) Disseminated in eruptive rocks. (c) Stockwork deposits. (d) Contact deposits. (e) Fahlbands. B. Regular. (/) Segregated veins. {g) Gash veins. {h) True or fissure veins. 464 KEMP'S ORE DEPOSITS. (11) J. S. Newberry, School of Mines Quarterly, March, 1880, May, 1880. I. Superficial; II, Stratified. (a) Forming entire strata. (6) Disseminated through strata, (c) Segregated from strata. III. Unstratified. (a) Eruptive masses. (6) Disseminated through eruptive rock. (c) Contact deposits. (d) Stockworks. (e) Fahl bands. (/) Chambers. {g) Mineral veins. 1. Gash veins. 2. Segregated veins. 3. Bedded veins. 4. Fissure veins. (13) J. A. Phillips, Ore Deposits, 1884, I. Superficial. (a) By mechanical action of water. (6) By chemical action. II. Stratified. (a) Deposits constituting the bulk of metalliferous beds formed by precipitation from aqueous solution. (&) Beds originally deposited from solution but subsequently altered by metamorphism. (c) Ore disseminated through sedimentary beds, in which they have been chemically deposited. III. Unstratified. (a) True veins. (6) Segregated veins. (c) Gash veins. (d) Impregnations. (e) Stockworks. APPENDIX I 455 (/) Fahlbands. (g) Contact deposits. {h) Chambers ot pockets. It is at once apparent that Whitney's schenae contains the essentials of the others, which are merely slight modi- fications. Newberry introduces impregnations, chambers, and bedded veins.. The first named is a useful term, although it is not always easy to distinguish impregnations from others earlier given. Thus, they may be very like the division, dis- seminated through strata, or disseminated through eruptive rock, or, if in metamorphic rock, fahlbands. The word is also used to indicate places along a vein where the ore has spread into the walls. The term "chambers," or "caves," has found application in the West, and is a useful addition. Bedded veins appear also in von Cotta above (No. 6). Phillips seeks to explain the methods of origin in his use of Whitney's scheme and clearly feels the importance of empha- sizing the genetic principle more strongly. Much of it is im- plied in the simpler phraseology, however, and the extended sentences lack the incisiveness of the earlier schemes. The arrangement as set forth by Whitney is worthy of high praise, and the scheme is one of the manj' valuable things in a book that has played a large part in the economic history of the United States. D. Schemes Largely Based on Origin. (13) J. Grimm, Lagerstdtten, 1869. I. Gemengtheile oder grossere EinschliJsse in den Ge- birgsgesteinen. Einsprengung, Impragnation. (Essential component minerals and inclusions in country rock. Impregnations.) (a) Ursprungliche Einsprengung. (Original with the inclosing rock.) (6) Von anderen Lagerstatten weggefiihrte Bruch- theile, etc. (Fragments brought from a dis- tance. Placers, ore-bearing boulders. Brec- cias. ) 456 KEMP'S ORE DEPOSITS. II. Untergeordnete Gebirgsglieder oder besondere Lager- statten. (Subordinate terranes or special forms of Deposits.) (a) Plattenforinige Massen. (Tabular masses.) 1. Lager oder Flotze. Bodensatzbildung. (Beds, strata.) 2. Gauge, Klufte, Gangtriimmer, etc. (Veins of varying sizes.) 3. Plattenformige Erz-ausscheidungen und Anhaufungen. (Segregated veins.) (6) Stocke und regellos gestaltete Massen. (Stocks and irregular masses.) 1. Lagerst6ckeLinsenstocke,Linsen. (Len- ticular deposits, etc.) 2. Stocke, Butzen, Nester, etc. (Masses, pockets, etc.) 3. Stockvi^erke. (Stockworks. ) (14) A. von Groddeck, Lehre von den Lagerstdtten der Erze., 1879, p. 84. I. Urspriingliche Lagerstatten (Primary deposits). A. Gleichzeitig mit dem Nebengestein gebildet. (Formed at the same time veith the walls. ) 1. Geschichtete. (Stratified.) (a) Derbe Erzflotze. (Entire beds in a stratified series. ) (6) Ausscheidungsflotze. (Disseminated in beds. ) (c) Erzlager. (Lenticular beds, mostly in schists.) 2. Massige. (Massive; the word is nearly synonymous with igneous.) B. Spater wie das Nebengestein gebildet. (Formed later than the walls.) H. Hohlraumsfullungen. (Cavity fillings.) (a) Spaltenfiillungen oder Gauge. (Fissure fill- ings or veins.) (1) In' massigen Gesteinen. (In igneous rocks.) APPENDIX I. 457 Forms due to the text- ure of the inclosing rock, or to its mineral constitution, or to both causes. (3) In geschichteten Gesteinen. (In strati- fied rocks). (&) Hohlenfiillungen. (Chambers.) 4. Metamorphische Lagerstatten. (Altera- tions, replacements, etc. ) II. Triimmer-lagerstatten. (Secondary or detrital de- posits.) (15) K. Pumpelly, Johnson's Encyclopcedia, 1886, VI., 22. I. Disseminated concent ra tion. (a) Impregnations, Fahl bands. II. Aggregated Concentration, (a) Lenticular aggrega- tions and beds. (6) Irregular masses. (c) Reticulated veins. (d) Contact deposits. III. Cave deposits. IV. Gash veins. V. Fissure veins. VI. Surface deposits. (a) Residuary deposits. (b) Stream deposits. (c) Lake or bog deposits. These three are all excellent, and give some interesting variations in the several points of view from Mrhich each writer regarded his subject. There are instances in the two German schemes where it is difficult to render the original into a corresponding English term and recourse has been had to the explanatory text. Grimm especially writes an obscure style. He divides accordingly as the ore forms an essential and integral part of the walls or a distinct body. Von Grod- deck has in view the relative time of formation as contrasted with the walls. Grimm afterward emphasizes geometrical shape, but this von Groddeck practically does away with, and continues more consistently genetic. His scheme might per- haps come more appropriately in the next section. ] Forms chiefly due to J. pre-existing open cav- j ities or fissures. 458 KEMP'S ORE DEPOSITS. Pumpelly's conception varies considerably from the others. He writes, as his full paper states, in the belief that the metals have all been derived primarily from the ocean, whence they have passed into sedimentary, and, by fusion of sediments, into igneous rocks. The group of residuary surface deposits, carrying out as it does a favorite idea of Professor Pumpelly, as set forth in his papers on the secular decay of rocks, is an important distinction. E. Schemes Entirely Based on Origin, (16) H. S. Munroe. Used in the Lectures on Mining in the School of Mines, Columbia University. I. Of surface origin, beds. ^ (a) Mechanical (action of moving water). 1. Placers and beach deposits. (6) Chemical (deposited in still water). 1. By evaporation (salt, gypsum, etc.). 2. By precipitation (bog ores). 3. Residual deposits from solution of lime- stone, etc. (hematites). (c) Organic. 1. Vegetable (coal, etc.). 2. Animal (limestone, etc.). (d) Complex (cannel coal, bog ores, etc.). II. Of subterranean origin. (a) Filling fissures and cavities formed mechani- cally. 1. Fissure veins, lodes. 2. Cave deposits— lead, silver, iron ores. 3. Gash veins. The cavities of 2 and 3 are enlarged by solution of limestone. (6) Filling interstitial spaces and replacing the walls. 1. Impregnated beds. 2. Fahlbands. 3. Stockworks. 4. Bonanzas. 5. Masses. APPENDIX I. 459 This scheme covers all forms of mineral deposits, whether metalliferous or not, while most of those previously given, as well as the one that follows, concern only metallifer- ous bodies. The scheme is consistently genetic and was elab- orated because such an one filled its place in lectures on min- ing better than one based on form. The general principle on which the main sub-division is made differs materially from any hitherto given. Deposits formed on the surface are kept distinct from those originating below, even though the first class may afterward be buried. It is immediately after this scheme that the one in paragraph 1.06.05 finds its place. In the report of the State Geologist of Michigan for 1891-93 (issued January, 1893), pp. 144, 145, Dr. M. E. Wadsworth has published a "Preliminary Classification of Metalliferous or Ore Deposits." The main outline is as follows : I. Eruptive Deposits (a) Non-Fragmental. [h) Pragmental. II. Mechanical Deposits (a) Unconsolidated. (6) Consolidated. III. Chemical Deposits (a) Sublimations. (6) Water Deposits. (c) Impregnations or Replace- ments. (d) Segregations or Cavity De- posits. Each of the above, except III. (d), is then subdivided so that the table becomes practically a classification of rooks. Indeed, a moment's consideraton will show that the scheme in its main divisions is closely modeled after the prevailing classifi- cation of rocks. III. (d) Segregations or Cavity Deposits con- tains the following: 1. Pockets. 2. Chambers. 3. Contact Deposits. 4. Veins, including Gash Veins, Segregated Veins, Reticulated Veins or Stockworks, Contact Veins, Fissure or Fault Veins. The author states in some appended comments that the table is not limited to those deposits now practically worked (which we ordinarily understand the expression ore deposits to mean), but is intended to include all that have been or may be of value. But in this respect there is good ground for preferring to make 460 KEMP'S ORE DEPOSITS. our classifications in ore deposits, as in mineralogy, zoology, etc., embrace only the authenticated varieties, expecting addi- tions to be incorporated as discovered and suitably described. The same general grouping as this scheme employs is inde- pendently adopted by E. S. Tarr, in the Economic Geology of the Ijnited States, 1894. For the meeting of the American Institute of Mining Engineers, held in connection with the various congresses at the World's Fair in Chicago, July, 1893, Professor Franz Posepny, of Vienna, contributed a grand essay on the "Origin of Ore Deposits." The materials for it were specially as- sembled by Professor Posepny while,giving a course of lectures at the Pribram Mining Academy in the ten years following 1879. The paper is a theoretical discussion of the origin of ores, with illustrations selected from all parts of the world, but especially from Europe and America. It forms one of the most important contributions to the literature that has yet been made. Posepny distinguishes at the outset between rocks and mineral deposits; i.e., between original materials, such as wall rock, and secondary introductions, such as veins, etc. The former he calls "idiogenites," the latter "xenogenites," basing the names on the familar Greek terms that run through all our literature. The latter are especially characterized by "crustification," by which term is indicated what has been called "banded structure," on p. 47. The subject of cavities is then taken up, and, while minute pores are stated to be in all rocks, a distinction is made between the larger openings, which originate in a rock mass as a part of its own structure, such as contraction joints in igneous rocks, amygdaloids, and the like, and those induced by outside causes, such as fault fissures. The circulation of water through these is next treated: first, surface waters or "vadose" circulations, which descend; second, ascending waters from great depths, such as springs in deep mines, hot springs, etc. The common salts in solution in these latter are tabulated, being of course mostly alkaline carbonates, sulphates, chlorides, etc. The "exotic" metallic admixtures which would bear on the origin of ores are next discussed, so far as possible with analyses of actual cases. The alterations produced by mineral springs in rocks and the struc- APPENDIX I. 401 tural relations of the deposits of mineral springs, especially aa expressed by "crustification," are then described. This pre- liminary material clears the way for the general discussion of the origin of ore bodies. The argument running all through the paper is that ore bodies, even when apparently interbedded with sedimentary rocks, are of secondary introduction and, in general for veins, are from deep-seated sources. Precipitation from descending solutions and filling by lateral secretion are strongly controverted. The discussion of origin follows in its arrangement the fol- lowing classification of ore deposits : I. Filling of spaces of discission (fissures). II. Filling of spaces of dissolution in soluble rocks. III. Metamorphic deposits in soluble rocks; in simple sedi- ments ; in crystalline and eruptive rocks. IV. Hysteromorphic {i.e., later or last formed) deposits. Secondary deposits due to surface action {i.e., placers, etc.). The treatment, both in the introductory pages and in the later discussions, is often strikingly similar to that of this book, and the underlying argument is much the same. The stand- point in both essays is essentially a genetic one, and the main difference lies in the fact that the>one is an exposition of an in- dividual's views, fortified by examples from all parts of the world; the other endeavors to be a judicial statement, with a fairly complete description of the ore bodies of the United States and Canada alone. The writer differs with Posepny however in the greater weight given to the ores of igneous origin. 1.06.38. An extended treatiseon the useful minerals, earthy as well as metallic, by MM. E. Fuchs and L. De Launay, has recently appeared {Traite des Gites Mineraux et Metalli- feres, Paris, 1893). The book is based on the lectures on economic geology delivered in the Ecole Superieure des Mines, at Paris, in the last fifteen years by the two authors. (Pro- fessor Fuchs died in 1889, and was succeeded by Professor De Launay.) A vast amount of valuable information is brought together and discussed from various points of view, useful applications and methods of treatment being set forth as well as geological occurrence. The work is encyclopedic in scope 462 KEMP'S ORE DEPOSITS. and affords a reader descriptions of mineral resources and refer- ences to their literature in every quarter of the world. So far, however, as the United States are concerned the authors have suffered from the unavoidable limitations of those not native and conversant in a discriminating way with our literature. Nevertheless they have endeavored to give a large share of their space to this country, and where prominent monographs have appeared they have been read with care, but in many cases reference to later papers and descriptions would have im- proved the text. A later edition will doubtless correct these. The classification of ore deposits as well as other useful minerals on a genetic principle has evidently been in many minds in the last few years. Mr. Frederick Danvers Power,' of Melbourne, Victoria, reviewed the subject in 1892, and after giving the schemes of others and summing up the various characteristics of veins, has formulated a classification whose main divisions are as follows: I. Contemporaneous; Indigenous. II. ffletasomatic or Chemical Alteration of the Original Constituents. III. Subsequently Introduced ; Exotic. Each of these has then a number of subdivisions too numerous to be repeated here. Prof. William 0. Crosby,^ of Boston, has recently discussed the same subject in a very suggestive way. The main head- ings are: A. Deposits of Igneous Origin (Igneous rocks) ; B. Deposits of Aqueo-Igneous Origin ; C. Deposits of Aqueous Origin. The first and last are then subdivided at considera- ble length, but the second is chiefly limited to the pegmatite (granitic) veins which attend many plutonic intrusions. Lack of space prevents the full reproduction of both these schemes, but sufficient has been mentioned, it is hoped, to indicate the line of attack and to place a reader desiring to look the sub- ject up in touch with the originals. ' •' The Classification of Valuable Mineral Deposits," Trans. Australas. Inst. Min. Eng., 1892. ^ "A Classification of Economic Geological Deposits based on Origin and Original Structure," Amer. Oeol, April, 1894, p. 340. The paper also appears in the Technological Quarterly, INDEX. Abiquiu, N. M., copper ores, 324. Acadian stage, 4. Adairsville, Ga., aluminum, 404. Adams, F. D. , on ores of Treadwell Mine, 391. Adams Co., Penn., limonites, 104. Adams Co., Ohio, Clinton ores, 114, 11.'5. Adirondacks, N. Y., magnetites, 160. Admiralty Islands, Alaska, gold de- posits, 393. Agglomerates, 381. Ainsworth District, B. C, gold mines, 894, 395. Alabama, aluminum, (bauxite), 404. Clinton ore, 114, 117. i Copper, 194. Gold mines, 378. Limonites, 104. Tin ores, 444. Alaska, geology of, 885. Gold, 393. Treadwell mines, 390. Alder Gulch, Madison Co., Mont., 317. Aleutian Islands, Alaska, 385. Algonkian system, 4. Allamakee Co. , Iowa, hnionite, 98, 99. Ahnaden, Spain, mercury, 434. Alno, Sweden, 61, 175. Alta mine, Jefferson Co., Mont., 317. Alturas Co., Idaho, 827. Aluminum, in bauxite, 404. Origin, 404^10. Sources, 403. Amador Co. , Cal. , copper mines, 195. Animikie series, 4. Annie Lee mine, Colo., 398, 305. Anthony's Nose, N. Y., nickel ores, 430. Pyrite ores, 184. Anticlines, arrested, 11. Defined, 11. With shattered bends, 17, 19. Antigonish Co., Nova Scotia, hema- tite, 130. Antimony, 410. Apache Co., Ariz., silver and gold ores, 335. Apollo mine, Unga Island, Alaska, 393. Appalachians, general description, 7. Geology of gold deposits, 376. Manganese ores, 418. Appendix, 447. Remarks on, 448. Appleton, Wis. , fold at, 30. Arohean Group, classification, 4. Argentine, Clear Creek Co., Colo , 295. Arizona, copper mines, 314^330. Geology, 334. Gold deposits, 334. Lead-silver ores, 379. Silver deposits, 334. Arkansas, antimony, 411. Bauxite, 404-406. Iron ores, 96, 97. Manganese, 430. Nickel, 440. Silver mines, 383. Arksut Fjord, Greenland, 403. Arlington, N. J., copper mines, 333. Armstead H. H., Jr., gold ores, of Idaho, 334. Arrow Lakes, B. C, upper and lower, 394. Arsenic deposits, 413. (See Gold in Canada. ) Ascension by infiltration, 40, 41-43. Ashcroft iron mines, Colo., 170. Ashland mine. Iron wood, Mich., 143. Aspen, Pitkin Co., Colo., 45. Iron mines, 170. Lead and silver, 368. Atlanta, Elmore Co., Idaho, 335. Atlantic Border gold, 288. Lead, 236. Silver, 383. Augusta Co., Va., manganese, 418. Auriferous beach sands, 348. Gravels, 853. 4:64 INDEX. Austin, Nev., antimony, 411. Gold and silver ores, 339. Avala, Servia, mercury, 434. B. Bachelor Mt,, Colo., 293. Baker Co., Ore., 347. Gold mines, 348. Bald Butte Group, Deer Lodge Co., Mont., 320. Baldy Mt., Utah, 333. Baltimore Region, chromite, 414. Banded structure of veins, 47. Bannack City, Mont. , 317. Banner district, Idaho, 325. Barker mining district, Meagher Co., Mont., 320, 331. Barton Hill, N. Y., magnetite, 163. Barus, C, on electrical activity in veins, 52, 53. Experiments on the Comstock Lode, 343. Basal granite, 388. Bassick mine, Colo., 47, 49, 58, 396. Batesville, Ark., manganese, 420. Bath Co., Ky., Clinton ores, 115. Battle Mt., Teller Co., Colo., 305. Bauxite, 404-407. Bayley, W. S., on Michigan iron ores, 137, 139. Bear Lake Co. , Idaho, 337. Bearpaw Mt., Mont., 333. Beaver Co. , Utah, gold and silver, 333. Beaverhead Co. , Mont. , gold and sil- ver, 317. Becker, G. F., on Alaska mines, 390. On cinnabar, 30, 44, 373. On Comstock Lode, origin, 340- 344. On gold ores, 35, 376, 378. On gold in Mad Ox mine. Gal., 368. On gravel beds, Cal., 356. On joints, 15. On quicksilver, 435. On silver ores, 35. On Sorefs principle, 67. On Sulphur Bank mine, 437. On Washoe rocks, 345. Beds defined, 6. Bell, Robert, on Hudson Bay gold ores, 338. Belmont, Nev., srold and silver ores, 338. Belt formation 6f Montana, 315. Bench gravels, Alaska., 393. Bennet mines, Alaska, 393. Benson mine, N. Y., iron ores, 166. Benton stage, 5. Berks Co., Penn., iron ores, 169. Bernallilo Co., N. M., 386. Berner's Bay, Alaska, gold, 393. Bertha mines, Va., zinc, 347. Bessemer limit of Lake Superior ores, 85. Beulah antimony mine, Nev., 411. Big Cottonwood Canon, Utah, 374. Big Creek, Nev., 411. Big Hill, Penn., 175. Bingham Canon, Utah, 339. Bingham Co., Utah, 274. Birch Creek series, 388. Birmingham district, Ala., iron ores, 118. Bisbee, Ariz., copper, 317. Region, gold and silver, 336. Bischoff, on silicate of gold, 373. Bismuth, 412. Bitter Root Mts., Idaho, 333. Black-band iron ore, 107. Black Hills, S. B., 57. Geology, 309. Gold in Potsdam, 309. Placers, 309. Tin, 443. Black Hornet district, Idaho, 325. Black Lake asbestos mine, 416. Black rauge copper mines, Ariz., 330. Blake, W. P., aluminum deposits, N. M., 407. Antimony ores, Utah, 411. Copper Basin ores, Ariz., 231. Deep Creek ores, Utah, 333. Gold and silver. Tombstone, 336. Lead and zinc ores, 336. Mercury, Texas, 438. Silver King mine, Ariz., 336. Zinc ores, N. M., 359. Blanco staige, 5. Blende in the Rocky Mts., 258. Blezard mine, Ontario, 436. Block iron ore, 107. Block Island, R. I. , magnetite sands, 181. Blow, A. A., cited on faults. 21, 22. Origin LeadviUe ores, 265. Blue lead in Cal., gravels, 355. Blue Mts., Oregon, 347. Bodie, Cal. , gold and silver, 353. Bog iron ore, 87-93. Boise district, Idaho, 335. Bonanza City, Idaho, 335. Bonanza, defined, 49. Bonne Terre, Mo. , lead mines, 228. Bonneville, Lake, Nev., 337. Bonsacks, Va. , illustration of gossan, 51. Zinc mines, 249. Boss of igneous rock defined, 12. Boston Mt., Ark., 421. INDEX, 465 Boulder Co., Colo., 306. Iron ores 109. 170 Box Elder Co., Utah, 329. Boyd, C. R., Bertha mine zinc ores, 248. On production of Big Hill mine, Penn., 179. Boye, Dr., iron ores, 103. Boyertown, Penn., iron mines, 179. Bradley, F. P. , on limonites, 104. Brandon, Vt., iron ores, 100. Manganese ores, 418. Branner, J. C, origin of, Ark., alu- minum, 406. Brazil, iron ores, 17.'5. Brewer mine, S. C. , 380. Bridal chamber mine, N. M., 361. Bridger stage, iS. Bristol, Conn. , copper deposits, 223. British Columbia gold gravels, '324. Platinum, 441. Britton, N. L. , on Staten Island bog ores, 91. Magnetite ores, N. Y. , 167. Broadwater Co., Mont., 319. Brooks, T. B., on Marquette district, 135. Browne, D. H., on isochemio lines, 183. Browne, R. E. , on Califoi'n;a gravels' 361. Bryant, Ark . aluminum, 406. Bucks Co., Penn., iron ore, 169. Buckwheat zinc mine, N. J., 353. Buena Vista mine. Cripple Creek, Colo., 30.0. Bull Domingo mine, Colo. , 49, 297. BullMt., Colo., 305. Burden spathic ore mines, Hudson N, Y., 110. Burra Burra mine, Tenn. , 192. Purro Mt.. New Mexico, 285. Putte, Mont,, 86, 44. 51, .W, 315. Copper ores, 196, 199, 200, 202. Development of, 200. Placers near, 354. Calaveras Co. , Cal., 195. Caldwell Co., Ky., lead and zinc mines, 339. Caledonia, iron mines. Mo., 135. Calico, silver district, Cal., 351. California Bar, Idaho, 824. California, antimony, 410; chromite, 415. Copper mines, 195. Geology, 349. Gold gravels. 353, 360, 861. Gulch, near Leadville, Colo., 295 California, Lead-silver ores, 279. Magnetite, 171. Mercury, 434. Platinum, 441. Tin, 825. Gallon, on scheme of classiflcation of ore deposits, 452. Calloway Co., Tenn., 193. Calumet and Heola copper mines, Mich., 308. Calvin, S., on limonites, 99. Ca3mbrian system, 4. Campbell Mt.. Colo., 293. Campbell, J. L., on limonites, 94. Camp Floyd district, Utah, 830. Campo Seco, Cal. , copper mine, 196. Canada, gold, 400, 412. Magnetite ore mines, 166, 173. Canadian Northwest, geology, 385. Series, 4. Canon City, Colo., zinc works, 358. Diablo, Ariz., 19. Cape Ann granite, 18, 14. Cape Breton, Nova Scotia, gold ores, 397. Manganese ores, 422. Capelton, Quebec, pyrite mine, 184. Carbonate iron ores, 107. Lead-silver, S. D., 272. Lead-silver, Utah, 376. Carbonifex'ous series, 5. System, 5. Carbonic acid in subterranean waters, 28. Caribou Hill, Colo. , magnetite, 174. Carlyle, W. A , on Slocan veins, 895. Carolinian gold belt, 378. Carpenter, F. R.; on Black Hills tin, 448. Carroll Co., Md., iron ore, 102. Va., iron ore, 103. Cartersville, Ga. , manganese, 418. Cascade Co., Mont., 321. Mts., Cal.,. 349. Cascaria, Durango, Mex. , tin ores. 444. Cason property. Ark., 431. Cassia C'o., Idaho, 327. Cassiar district. Alaska, 393. Cassiterite,' 441. Castillo Co. , Colo. , magnetite, l70. Castle Mts. district, Mont. , 830. Cave mine, Utah, lead silver ore, 58, 276. Cave Spring manganese mines, Ga., 430. Cavities, secondary modifications, 36. Cayuga Co., N. Y., Clinton iron ores, 11.5. 466 INDEX. Cazin, F. M. F., on Silver Reef , Utah, ores, 333. CeboUa district, Colo., magnetite, 175. Cedar Mt., Mo,, 157. Cenozoit! Group, 5. Central California, 849. Central district, Mich., copper, 208. Cerro de Mercado, Mex., iron ores, 187. Cerro Gordo district, Cal., 353. Chaffee Co., Colo., 395. Magnetite, 170. Chalcopyrite, of igneous origin, 61- 65. With pyrite, 189. Chamber deposits, 58. Chamberlin, T. C, 68. On Lead ores, 335, 336. Champlain series, 5. Chandler and Pioneer mines, Minn., 148. Chapin mine, Mich. , 138. Charlemont, Mass. , pyrite mines, 184. Charles Dickens mine, 325. Chateaugay iron mines, N. Y., 85. Chatham, Conn., nickel ore, 430. Chattahoochee stage, 5. Chattanooga, Tenn., iron ores, 117. Chaudiere River, Can., gold gravels, 400, Chauvenet, R., on Colorado magne- tite, 170. Iron ores, 98. Chazy stage, 4. Cheever mine, N. Y., 163. Chemung series, 5. Cherokee Co. , Kansas, 240. Cherry Creek, Mo., 315. Cherry Valley, Mo., 133. Chester, A. H., on yield of standard iron ores, 85. Co., Penn., aluminum ores, 407. F. D., on chromite, 415. Mass., alumium deposits, 410. Chibas, E. J. gold mining, Columbia, 299. Chico stage, 5. Chipola stage, 5. Chisholm, F. F., on Cuban iron ore, 187. Choteau Co., Mont., 322. Chromite, analysis, 414. Dissemination in serpentine, 414. Of igneous origin, 61, 63. Uses, 414. Chromium, 413. Chugwater Creek, M'^yo., iron ores, 171. Churchill Co, , Nev, , silver ores, 340. Church, J. A., on Comstock Lode, 340. On faults, 24. Chutes, 49. Cincinnati stage, 4. Uplift, 9. Cinnabar, 424. Claiborne stage, 5. Clarke Co., Mont., 330. Clarke, E., on lead-silver ores. Lake VaUey, N. M., 261. Clarke, F. W., on earth's crust, 447. Clarke Timber Reserve, Mont., 321. Classification of ore deposits, 447. Clay, attrition, in a vein, 49. Ironstone, 106. Seam, selvage, 49. Clavton, J. E., cited, 49, 319. Clear Creek Co., Colo., 306. Clear Lake, Cal., 427. Clerc, F. L., on Missouri ores, 340, 242. Cliff copper mine, Mich., 208. Clifton copper district, Ariz., 336. Clinton Co., Ohio, 114. Ores, 57, 114, 131, 446. Stage, 4. I Coal measures, cla,ssification of, in Penn., 107. - Coastal Plain, 7, 376. Coast Rafige, Cal., 349, 445. Mercury, 424: Cobalt, in Sudbury Region, 438. (See nickel, 416.) Cochise Co., Ariz., lead-silver, 379. Cceur d' Alene, Idaho, lead-silver ores, 274, 324. Colfax Co., N. M., silver and gold, 286. Colombia, South America, 441. Colorado, Creede, gold ores, 393. Geology, 286. Iron ores, 98, 170, 174. Lead-silver mines, 362-373. Magnetite, 170. Plateau, 445. Stage, 5. Silver and gold, 286-307. Columbia Co. , N. Y. , lead ores, 327 Limonites, 101. Columbia Hill, Cal., gold gravels, 354. Mines, Idaho, 334. River district, B. C, 394. Comanche stage, 5. Commonvyealth mines, Mich., 138. Comstock Lode, 20, 35. Geology of, 340-345. Comstock, T. B., on Colorado gold ores, 288. On Colorado lead-silver ores, 723. INDEX 467 Conejos Co., Colo., 296. Connecticut bismuth, 412. Copper contact deposits, 333. Lead mines, 327. Limonite, 101. Nickel ores, 430. Contact deposits, .58, 69. Continental divide, 321. Montana, 815. Coosa Valley, Ga. , aluminum, 404. Copper Basin, Ariz., 330. Copper Cliff mine, Ont. , 436. Copper Creek, Colo., 394. Copper districts in Arizona, 331. Copper Falls district, Mich., 308. Copper Mt., Ariz., 215. Copperopolis, Cal., 196. Copperopolis mine, Utah, 321. Copper ores, analysis, 189. Discovery of, in Michigan, 211. In mine waters, 52. In sandstone, 332, 233. Origin of, 209. Copi)er, tables of production, 83, 90, 97, 235. Corniferous stage, 5. Cornvrall, Penn., iron mines, 85, 175. Cortland series, 61. Corundum of igneous origin, 56, 61, 63. Cotta, B. von, cited, 451. On method of vein filling, 39. On schemes of cla.ssification of deposits, 449. Courtis, W. M. , on gold quartz 363. Cow Bay, Nova Scotia, 399. Cramer, F. , on faults, 20. Cranberry, N. C, magnetite, 169. Crawford Co., Mo., hematites, 69, 133. Credner, H., on origin of Marquette ores, 135. Creede, Colo., 393. Crescent mine, Utah, lead-silver, 275. Cretaceous system, 5. Crimora, Va., manganese, 418. Cripple Creek, Colo. , 300. Cripple Creek, Va. , iron ores, 103. Crismon Mammoth copper mine, Utah, 231. Lead-silver, 375. Crittenden Co., Ky., lead and zinc ores. 389. Crosby, W. O , on joints, 15. Cross, W. , Bassick mine, 397. Map of Telluride, Colo., 290. Pike's Peak deposits, 804. Crustiiication, 47. Cuba, iron mines, 186. Cumberland mine, Mont. , 330. Cumberland iron mine, R. I. , 173. Cumberland, R. I., peridotite, 56, 61. Curry Co. , Ore. , gold gravels, 348. Curtis, J. S., 44, 46. Eureka, Nev., 377. Metasomatic interchange, 83. Silver in poi'phyry, 35. Cushing, H. P., discovery of augite syenites, 161. Custer Co., Colo., 396. Idaho, 334. Custer mines, Idaho, 835. Bacy Flat, S. D.. 313. Dade Co., Mo., 69. Dahlonega, Ga., gold deposits, 377. Dakota stage, 5. Dall, W. H., on Alaska, 388. Daly West mine, Utah, 329. Dana, J. D., on limonites of N. Y., 105. Daubree, on joints, 15. Tin ores, 70. Water in rooks, 37, 38. Davidson, Mt., Nev., 340. Davis Creek, Va., 108. Davison Co. , N. C. , lead deposits, 328. Dawson, G. M., 888. Kootenay Lake, rock series, 394, Origin of gold, Alaska, 375. Day, John, stage, 5. Deadwood Gulch, S. D., 310. Dean iron mines, N. Y., 167. Dease Lake, gold mines, Alaska, 394. Deep Creek, Utah, lead-silver mines, 275. Silver and gold mines, 882. Deep gravels, California, 354. Deep River, N. C. , iron ores, 109. Deep River stage, 5! Deer Lodge Co., Mont, 319. Deer Trail mine, Utah, 838. De la Beohe, on formation of veins, 53, De Launaj', L. , on vein fillings, 88. Delaware, ohromite, 414. Del Noi-te Co., Cal., chromite, 415. Deloro, Can., arsenic mine, 413. Dent Co., Mo., iron ores, 183. Devereux, W. B., gold gravels of Black Hills, 311. Magnetites of Colo. , 70. Devonian system, 4. Diadem Lode, Cal. , 368. Diamond Hill mines, Mont. , 319 Dike, defined, 13. Diller, J. S., on Cascade Range, Cal., 349. Geology of Sierras, Cal. , 859. Gold; Minersville, Cal , 369. Lead and zinc, Ky., 339. 468 INDEX. Diller, J. S., on Nickel ores, origin of, 439. Sandstone dilies, 450. Billsburg mines, Penn., 179, d'Invilliers, E. V. , on Big Hill mine, Penn., 178. Disseminated ores, 57. Dodge Go., Wis. , iron ores. 114. Doe Run Mo. , lead mines, 228. Dolomitization, 83. Dolores Co. , Colo. , gold and silver, 287. Dona Ana, Co., N. M., 260. Don, J. R. , on Australian gold Depo- sits, 283. Occurrence of gold in sea water, 373. Donald, J. T. on chromite, 416. Douglass Island, Alaska, 365, 390. Douglass, James, on Bisbee Copper ores, 217. Drinker, H. S., zinc ores of Penn., 351. Drumlummon mines, Mont., 320. Dry Cafion mines, Utah, 275, 330. Ducktown, Tenn., 51, 103. Chalcopyrite mines, 190. Pyrite mines, 184. Dutchess Co., N. Y., limonites, 101. Dutton, Capt. C. E. , on geology of N. M., 284. Dyestone iron ore, 114. Eagle Co., Colo., 294. Eagle Hill, porphyry, Utah, 380. Eagle River, Colo., 368. Eakins, L. G. , on eruptive rocks, 35. East Tenn. , mine, 192. East Tintic district, Utah, limonite, 100. Eastern sandstone, Keweenaw Point, Mich., 205. Egan Cafilon, Nev., 839. Egleston, T., on solubility of gold, 372. El Dorado Co., Cal., 363. Electrical activity of veins, 53. Elizabethtown, N. Y., 173 Elk Mt., Colo., iron ores, 170. Elkhorn mine, Mont., 58, 317. Elko Co. , Nev. , silver ores, 340. Elmore Co., Idaho, 325. El Paso, Texas, tin ores, 444. Ely copper mine, Vt., 190. Ely, Minn., iron ores, 144, 150. Emma mine, Utah, 275. Emmons, S. F., on Bassick mine ores, 297. On Butte copper ores, 197. On contact deposits, 67. On hematite ores, 134. Emmons, S. F. , on Lead-silver ores of Colo., 270, 273. On Leadville ores, 268. 365. On metasomatic interchange, 83. On replacements, 44. On silver ores, 85, Endlioh, F. M., on gold mines of Colo., 288. Enriquita mercury mine, Cal. , 426. Enterprise, Miss., iron ores, 109. Eocene series, 5. Esmeralda Co., Nov., 340. Eureka, Nev., 35, 51. Aragonite, 46. Lead-silver ores, 377. Silver and gold, 339. Europe, mercury of, 434. Eutaw stage, 5. Evans nickel mine, Ont. , 486. Evigtok, Greenland, aluminum, 403. "Ewige Teufe", 36. Fahlbands, defined, 73. Related to zones, 17. Fairbanks, H. W., on Cal., gold depo- sits, 859, 367. Tin deposits, 443. Parish, J. B., on veins at Newman Hill, Colo., 390. Faults. 17-25. Fayette Co., Penn., 108. Felch Mt., district Mich., 139. Fergus Co., Mont., 332. Finlay, J. R. , on iron ores of Penokee- Gogebic, 144-150. Flagstaff mine, Utah, 275. Flathead Co., Mont., 321. Flat River district, Mo., 238. Floetze, defined, 55. Florence mines, Mich., 138. Floridian stage, .5. Flucan, defined, 49. Foerste, A. F., on Clinton ores, 130. Folds, defined, 11, 12. Forest Queen mine, Colo., 294. Formation, defined, 6. Fortuna mine, Ariz., 337. Forty mile series, 388. Foster, on iron ores of Mich., 135. Fournet's series, 66. Fox Hill stage, 5. Franklin copper mines, Mich. , 208. Franklin Co., Mo., lead and zinc mines, 239. Franklin, Co., Va. , magnetite, 169. Franklin Furnace, N. J., iron ores, 167. Franklin Furnace, N. J., Zinc 251-257. Frazer, P., on Penn. limonites, 104. Frederick Co., Md., limonites, 102. Fremont Co., Colo., magnetite, 170. II INDEX. 469 French Creek mines, Penn. , 179. Friedensville zinc mines, Penn. , 250. Frisco, Utah, 376. Fritz Island mine, Penn., 179. Frost Drift, N. C. , 377. Fuchs, E, , on useful minerals, 461. Fv.nter's Bay Alaska, gold, 392. Gagnon mine, Butte, Mont., 201. Galena (town), S. D. , lead-silver mines, 373. Galvanic action in veins, 53. Gangue, defined, 55. Minerals, 33. Gap mine, Penn., 63, 65. Nickel ore, 429. Pyrite ore, 184. Gasconade sandstone. Mo., 133. Gatling arsenic mine, Ont. , 412. Gay Head, Mass., 109. Genesee antimony mine, Nev, , 411. Genesee stage, 5. Genth, F.A., on Boulder Co., Colo., 306. Geological classification, 4. Geology, general principles, 3. Georgetown, Colo., 306. Georgia, bauxite, 404, 408. CHnton ore, 114, 117. Gold ore, 379. Limonite, 108. Manganese, 418, 430. Georgian stage, 4. Geyser mine, Colo. , 30. Giants Eange, Minn., 151. Gibbonsville, Idaho, 334. Gila River, N. M., Aluminum depo- sits, 407. Gilbert. G. K., on faults, 18. Gilpin Co., Colo., 47, 305, 306. Copper ores, 303. Glacial series, 5. Glenariff, Ireland, aluminum ores, 407. Glendale, Mont., lead-silver deposits, 273, 317. Glenn, Wm., analyses chromite, 414. Globe district, Ariz., copper ores, 218, 319. Gold and silver ores, 33i. Gogebic Eange, Mich. , 69. Manganese ores, 438. Goleonda, Nev., manganese ores, 421. Gold, Alaska, 393. Analysis of minerals containing, 381. Chemical I'eactions in precipita- tion, 371. Classification of gravels, 361. Deposits, general examples, 380. Gravels, 353, 354, 393. Gold, introductory, 380. Quartz veins, 363. Statistics, 401. Gold Hill, Colo., 305. Good Night stage, 5. Gossan, defined, 51. Gothic district, Colo., 394. Gouge defined, 49. Graham Co. , Ariz. , 336 Grampian Mt., Utah, 376. Grand Canon of Ariz., 334. Granite Co., Mont., 319. Granite Mt. mine, Mojt., 319. Grant Co., N. M., silver and gold ores, 385, Grant Co. , Ore. , gold mines, 348. Grant, U. S., on Rainy Lake district, 384. Grassy Hill, Penn., 175. Great Basin, 445. Arizona, 334. California, 349. Nevada, 337. Oregon. 347. Utah, 338. Great Eastern mercury mine, Cal., 436. Great Falls, Mont., iron ores, 90, 109. Gold and silver, 331. Great Valley, 101, 103. California, 445. Great Western mercury mine, Cal. , 436. Greenbrier Co., W. Va. , hematites, 121. Green-eyed Monster mine, Utah, 333. Greenland, aluminum, 403. Gregory Company, Mont., 273. Greisen, defined, 70. Gresley, W. S. , on Mich, iron ore, 188. Griflin, P. H. , on Canada bog ore. 90. Grimm, J., on scheme of classifica- tion, 455. Groddeck, A. von, 73. On\ scheme of classification of ore deposits, 456. Groundwater, 37. Guadalcazar, Mex. , mercury, 424 Guadahipe mercury mine, Mex. , 436 Guanaoo, Chili, gold, 34. Guaymas copper mines. Lower Cal. , 321. Guerrero, Mex., hematite, 188. Gunnison Co., Colo., magnetite, 170. Gunnison Region, Colo., silver and gold, 394. H. Hade of a fault, 31. Hague, A., Comstock Lode, 340-344. Formation of magnetites, 174. Hamilton, Nev. , gold-silver ores, 338. 470 INDEX. Haile gold mine, S. C, 380. Harzburgite, 439. Hall, J., cited, 124. Hall's Valley, Colo. , bog ore, 90. Hamburg zinc mine, N. J., 353. Hamilton, Nev., 338. Hamilton series and stage, 5. Hammondville, N. Y., iron mines, 163-165. Handcart Gulch, Colo., bog ore, 90. Hanging Rock iron region, Ky. , 95. Hanna, on North Carolina gold belt, 380. Hanover, N. M., zinc ores, 359. Harford Co., Md., chromite, 414. Harney Peak, S. D., 314. Hartman.zinc mine, Penn. , 350. Hartwell iron district, Wyo., 154. Hastings Co., Ontario, 412. Haworth, E., on lead and zinc of Missouri, 242. Hayden's Survey, 823. Hayes, C. W., 388. On aluminum deposits, 405. Head Center mine, Ariz., 43. Hecla lead-silver mines, Mont., 373. Hecla mines, Mont., 317. Heim, cited, 23. Helena Company, Mont. , 373. Helena, Mont., 320. Hematite, brown, 87-106. Red and specular, 114^159. Henrich, C, on copper ores, Clifton district 216. Copper pyrite, Tennessee, 190. Gold of New Mexico., 286. Henry Co., Va., magnetite, 169. . Henwood, cited, 55. Herder, von, on vein fillings, 39. Hesse, Germany, bog ore, 92. Hestmandjo, Norway, chromite, 413. Highland Co., Ohio, CUnton ores, 114, High or deep gravels, Cal. , 354. HighwoodMt., Mont., 815. Hillebrand, W., on Geyser mine waters, 300. Gold deposits of Cal., 369. Vanadium, 86. Hill, R. C, Colo., gold, 287. Concentration of gold in veins, 51. Iron ores of Wyo. , 174. Mercur mines, 332. Replacements, 45. Hill, R. T., Mex., iron ores, 187. Hinsdale Co., Colo., gold and silver, 287. Hitchcock, E., on limonites, 100. Hoefer, H., on faults, 23. HoUister, cited, 2T5. Homestake mine, Colo., 394. Homestake mines, S. D., 313. Honorine mine, Utah, 375. Horizon, defined, 6. Horn Silver mine, Utah, 376. Horses, formation of, 48. Huancavelica, Peru, mercury mine, 424. Hubbard, L. L., on Mich., copper ores, 210. Hudson Bay, gold deposits, 40. Hudson River, stage, 4. Huitzuco, Mex., mercury mines, 434 Humboldt Co., Nev., antimony, 411. Gold and silver deposits, 340. Humboldt-Pocahontas mine, Colo., 399. Hunt.T. S. , on Canada magnetites, 173. Huronian ores, 127. System, 4. Hurst, limonite bank, Va., 93, Hussak, cited, 314. Ibapah range, Ut^h, 382. Idaho Basin, 335. Idaho City mining belt, 335. Idaho Co., Idaho, 324. Idaho, geology, 323. Copper, 332. Gold, 823. Tin, 448. Idaho Springs, Colo., 306. Iddings, J. P., cited, 59. Comstock Lode, 340-344. Idria, Austria, mercury, 424. Igneous rocks, defined, 6. As sources of metallic ores, 34, 59-63. Illinois lead zinc mines, 283. Impregnations, 57. Independence, Colo., 294, 305. India, aluminum ores, 410. International Geological Congress, 3. Inyo Co., Cal., antimony deposits, 410. Lead-silver deposits, 279. Iowa, iron ores, 98, Lead and zinc mines, 233. Ireland, aluminum ores, 407. Bog ores, 92. Iron Co., Utah, antimony deposits (411.) Hematites and magnetites, 180. Irons, defined, 66. Iron hat, defined, 51. Iron in nature, 86, 87. IronMt., Colo., 170. IronMt., Mont., 321. IronMt., Mo., 59, 71, 157. Iron ores, analyses, 85. Composition, 84, 186. INDEX. 471 Iron ores, Discussion of, 85-87. Impurities, 85-86. Iron ores, magnetite, 160-184. Iron ore localities: Adirondack Mountains, 160. Alabama, 104. Brazil, 175. Colorado, 98, 170-174. Connecticut, 101. Cuba. 186. Georgia, 103, 117. Hesse, Germany, 93. Ireland, 93. Kentucky. 95, 107. Clinton ore, 114. Maryland, 116. Massachusetts, 101. Mexico, 187. Michigan, 125-150. Minnesota, 96, 150, 174. Missouri, 96, 132. Mississippi, 109. New Jersey, 101, 160, 173. New York, 114, 167. North Carolina, 104-109, 160. Nova Scotia, 130. Ohio, 96-115. Oregon, 93. Pennsylvania. 93, 104, 112. Tennessee, 103, 114. Vermont, 100, 184. Virginia, 114, 169. West Virginia, 107, 114, 131. Wisconsin, 114. Wyoming, 171. Iron ore, pyrite, 184. Red and specular hematite, 140- l.=j9. Iron ores: SiluroCambrian limonites, 100- 106. Spathic, 113, Statistics, 186. Irving, E. D., cited, 305. Copper ores, origin, 209. " Fundamental complex," 138. Jlichigan. ores, 137. Penokee district ores, 139. Replacements, 44. Isle Eoyale mines, Mich., 307. Iiiochemic lines, 183. Jackson, C. T., on Penn. limonites, 104. Jackson stage, 5. Jacksonville, Ala., 404. Jacupiranga, Brazil, iron ore, 56, 61. Jalisco State, Mexico, hematite, 188. Jame.s River, Va. , hematites, 154. Jasper Co. , Mo. , lead and zinc mines, 341. Jefferson Co., N. Y., nickel ores, 133, 440. Jefferson Co., Mo., lead and zinc mines, 339. Jefferson Co., Mont., 317. Jenney, W. P., cited, 43. Gold deposits, 383. Lead and zinc mines of the Miss. Valley, 237, 348, 446. Lead and zinc mines of Mo. , 330, 345. Joachimsthal, Bohemia, cited on water, 31. John Day stage, 5. Johnson, L. C. , on limonites, 97. Joints, compression, 13, 14. Jones copper mine, Cal., 196. Joplin, Mo., zinc and lead mines, 340. Josephine Co. , Ore. . gold mines, 348. Juab Co., Utah, 330. Judith Mt., Mont., 315. Julien, A. A., on origin of magnetite, 318. Juniata district, Penn., Clinton ore, 116. Jurassic system, 5. Jura-Trias system, .j. K Kadiak Island, Alaska, gold ores, 393. Kansas, lead and zinc mines, 840. Kearney mines, N. Y. , iron ores, 135. Kelley lode, N. M., lead-silver ores, 360. Kemp, J. F. , on Iron Mt. , Colo. , ores, 174. On N. J. zinc deposits, 257. On Tenn. copper deposits, 193. Kennedy, W. , on nodular ores, 97. Kentucky, Clinton ore, 114. Lead and zinc ores, 339. Limonites, 95, 107. Kern Co., Cal, antimony, 410. Kerr. W. C, cited, 377. On N. C. magnetite ore, 169. On copper ores, 194. Keweenawan svstem. 4. 166. Keweenaw Point, Mich., 57, 304, Keyes, C. R. . on Mo. lead ores, 338. Kimbail, J. P., on chemistry of linronites, 112. On Cuban iron ores, 187. On formation of iron ores, 111, 113. On hematite, 124. On magnetite, 178. King, G, on Comstock Lode, 340, 343. 473 INDEX. Kingston, Canada, corundum de- posits, north of, 490. Kittitas Co., Wash., gold placers, 347. Klamath Mt., Cal., 359. Klausen, Austria, cited, 43, 43. Knight, W. C, cited, 174. On Hartwell iron ores, 154. Knob of igneous rock defined, 13. Knowlton, cited on Cal. deep gravels, 358. Koehler, G. , on scheme of classifica- tion of ore deposits, 453. Kongsberg. Norway, cited, 73. Kootenai Co. , Idaho, 334. Kootenay Lake, B. C, 394, Kwei-Chau, mercury deposits, Asia, 424. Laccolite defined, 13. Lager defined, 55. Lagorio, cited on ore deposits, 59. Lahontan Lake, Nev. , 337. Lake Champlain iron region, 160. Lake Co., Colo., 394. Lake of the Woods, gold district, 384. Lake Superior, copper deposits, 446. Gold and silver, 283. Iron deposits, 135, 446. Manganese ores, 423. Lake Valley, N. M,, 285. Lancaster Co , Penn. , chromite, 414. Lander Co., Nev., antimony mines, mines, 411. Gold and silver mines, 339. Lane and Hayward mines, Alaska, 392. Lane's bismuth mine. Conn., 413. Lansing, Iowa, lead and zinc mines, 285. La Plata Co.. Colo., 287. Larajnie Co., Wyo. , 154. Laramie stage, 5. Lassens Peak, Cal., 349 Lateral enrichments of a vein, 49. Lateral secretion, 40. 41, 43. Launay, L. de, cited, 461. Laurentian system, 4. Laur, M. F., on occurrence of alu- minum, 404. Lawson, A. C, on geology of Cal., 359. On California granite, 375. On Rainy Lake gold region, 384. Lead alone, 326. Lead and zinc, 333. Lead City, S. D. , 313, Lead, production of, 283. Lead series, 236. Lead-silver ores, 360-363. Lead veins in gneiss, 336. Leadville, Colo., cited, 17, 21, 35, 51. Copper mines, 331. Lead-silver mines, 263. Silver ores, 365. Le Conte, J. , on Cal. gravels, 356. On mercury deposits, Cal. , 437. On scheme of classification of ore deposits, 450. Lee Hill mines, Minn., 146. Leesburg, Idaho, 334. Lehigh Co., Penn., iron mines, 101, 169. Lemhi Co., Idaho, 334. Leonard, A. G., on Lansing mine, Iowa, 335. On origin lead-zinc of Miss. Val ley, 237. Lesley, J. P., cited, 120. On Marcellus stage, 94. On Penn. iron mines, 178. Lesquereux, on Cal. gravels, 355. Lewis Co., Mont , 320. Lewiston, Mont., 333. Libbey Creek, Mont., 333. Lignitic stage, 5. Limonites, analysis, 106. Iron ore, 87-106. Lincoln Co.. Nov., 338. Lindgren, W. , on Boise Co., gold veins, 335. On Cal. gold veins. 365. On Cal. gold, occurrence, 369. On Calico district, 351. On War Eagle claim, 397. Little Annie mine, Colo. , 295. Little Belt Mts., Mont., 321. Little Cottonwood Canon, Utah, 274. Little Rock, Ark. , aluminum, 406. Livingston Co., Ky., 239. Llano Co., Texas, copper mines, 204. Logan Co., Kansas, nickel ores, 440. London mines, Tenn., 192. Lottner-Serlo, on schemes of classifi- cation of ore deposits. 451. Louisa Co. , Va. , pyrite mines, 1^. Loup Fork stage, 5. Lovelock mines, Nev. , nickel, 440. Lovers Pit, Mineville, N. Y., 85. Low, A. P., on Hudson Bay iron ores, 154. Lowell. Mass , nickel ores, 430. Lower Helderberg series, 4. Lower Claiborne stage, 5. Low Moor, Va. , zinc ores, 95, 256. Lubeck, Me., lead mine, 337. Lucky Boy mine, Utah, 333. Lyman, B. S., on limonite, 94 Lvndhurst. Va., manganese, 418. Lyon Co. , Nev , 340. INDEX. 473 Lyon Co., Ky., 95. Lyon Mt., N. Y., iron ores, 163. M Madison Co., Mont., 316. MagdalenaMt., N. M., 260. Magna Charta mine, Butte, Mont., 319. Magnetite iron ore, 56, 60-63, 160-181. Analyses, 183. Beds. 160. Origin of deposits, 181. Sands. 180. Maiden, lilont., 323. Maine, copper pyrite, 190. Gold, 383. Tin, 444. Manganese ores, 416, 418. Mansfield ores, Penn., 121. Marcellus stage, 5. Margerie Snd Heim, cited on faults, 23. Maricopa Co., Ariz., 335. Mariposa Co., Cal., 363. Marlihamville, N. B., manganese, 422. Marmora. Can., arsenic mines, 412. Gold mines, 401. Marquette district, 129-136. Marquette range, 69. Marshall Mt., Colo., 306. Marshall tunnel, Georgetown, Colo., 50. Maryland, chromite, 414. Clinton ore, 116. Gold mines, 381. Limonite, 102. Mary Co., Tenn., 193J Marysville, Mont., 320. Marysville, Utah, 424. Massachusetts, lead mines, 227. Limonite, 101. Mayflower mine, Mont. , 317. Maynard, G. W., on chromite, 416. Mazon Creek, 111., 107. McCalley, H., aluminum, 406. McConnell, R. G., cited, 388. On Trail Creek rock series, 396. McCreath, A. S., cited, 107. On slates, 93. Meagher Co., Mont., 320. Means, E. C, referred to, 256. Medina stage, 4 Menominee district. Lake Superior, 135-139. Meramec hematite mines. Mo., 123. Mercur gold mines, Utah, 330. Mercury, occurrence of, 424. Merrill, G. P., cited, 35. Merritt, W. H., on Lake of the Woods district, 385. Mesabi district, Minn. , 134. Mesabi range, Minn., 144. Mesozoic group, 5. Metamorphic rooks, defined, 6. Metasomatic defined, 32. Methods of vein flUing, 39. Meunier, on origin of chromium, 413 Mexico, iron ore, 187. Mercury, 424. Tin, 444. Mexican mine, Alaska, 391. Miask, Urals, aluminum, 403. Michigan, copper, 204. Gold, 383. Iron, 125-150. Michigamme jasper, 137. Middle Hill, Penn , 175. Middletown, Conn., lead mine, 327. Midway stage, 5. Milan, N. H., pyrite mine, 184. Miller, Prof., on Kingston, Ont., aluminum, 409. Mine Hill, Cal., 358. Mine Hill. N. Y., zinc mine, 252. Mine la Motte, Mo., cited, 58, 69. Lead, 228. Nickel, 439, 440. Mineral Hill, Colo., 302. Mineville, N. Y., 73, 85. Mine waters, 52. Mining laws, 447. Minnesota copper mines, 213. Iron ore, Mesabi range, 150. Limonite, 96. Magnetite, 174. Miocene series, 5. Mississippi Valley, 19, 446. Iron ores, 109. Lead and zinc, 331, 333. Mississippian series, 5. Missoula Co., Mont., 321. Missouri, Cambrian red hematite, 1 22 Copper, 213. Lead ores of southeastern Mo., 328. ^ Limonite, 96. Red hematites, 122. Tin, 445. Zinc and lead in the southwest, 240. Moericke, cited, 84. Mohave Co. , Ariz. , 335. Moisie, Can., magnetite sands, 181. Monarch district, Colo. , 268. Monheim, V., on zinc ores of Stol berg, 257. Monocline defined, 11, 19. Mono Co., Cal., H52. Monroe, Conn., bismuth, 412. 474 INDEX. Montalban series, 4. Montana, geology of, 314. Copper, 203. Lead-silver, 273. Silver and gold, 314. Tin, 443. Montana stage, 5. Monte Cristo mine, Wash., arsenic, 412. Moore, P. N., on iron ores, 109. Morenci, Ariz. , copper district, 215. Morozewicz, J., cited 173. On laws of separation of ores, 63, 63. Mosquito range, Colo. , 262. Mother Lode of California, 363. Mount Baldy, Utah, 333. Mount Davidson, Nev. , 340. Mount Hope, N. J., 167. Mount Marshall, Colo., 306. Mount McClellan, Colo., 395. Mount Prometheus, Nev., 339 Mount Shasta, Cal., 349. Mule Pass, Mt., Ariz., 317. Mullica Hill, N. J., 89. Munroe, H. S., cited 71. On limonites, 41. On scheme of classification of oi-e deposits, 457. Murphee's Valley, Ala., 120. Murray nickel mine, Ont., 436. N Nacemiento copper mines, N. M. , 334. Nason, F. L. , on geology of Ring- vrood mines, 169. On N. J. zinc deposits, 353, 257. On Mo. iron ores, 158. Neal district, Idaho, 333. Neck of igneous rock defined, 13. Neihart mining district, Mont. , 330. Nelson Co. , Va. , tin ore, 444. Nelson, B. C, gold, 394. Neocene system, 5. Nevada, antimony mines, 411. Geology of, 337. Gold and silver deposits, 338. Mercury, 434. Nickel, 440. Nev(' Almaden, Cal. , mercury, 435. Newberry, J. S., on copper deposits of N. M., and Utah, 224. On iron ore, 120. On lead-silver deposits, Utah, 276. On Silver Reef, Utah, 333. On schemes of classification of ore deposits, 453. Newberry, W. E. , on Colorado mines, 271. New Brunswick, N. J. , copper mines, 190. New Caledonia nickel, 439. Newfoundland, chromite, 416. Copper, 190. New Hampshire, lead mines, 237. Tin, 444. New Idria mines, Cal., 436. New Jersey, copper ores, 338. Gold ores, 383. Iron mines, 173. Limonite, 101. Magnetite, 160. > Zinc mines, 353. New Jersey, Greensand stage, 5. New Jersey Zinc and Iron Co.'s mines, 253, 254. Newman Hill, Col., 34, 47, 50. Mines of, 338. New Mexico, aluminum deposits, 407. Copper, 224, 334. Geology of, 284. Lead-silver, 360. Silver and gold, 285. Zinc ores, 259. New River, Va. , limonite, 103. Newton, Cal , copper ore, 196. Newton Co. , Mo. , zinc mines, 340. New York copper mine, Ariz. , 319. New York, Clinton ore, 114, 120. Gold deposits, 383. Iron mines of the Highlands, 167. Iron ore of Adirondacks, 166. Lead mines, 337. Limonite, 101, 105. Ney Co., Nev., 338. Nez Perces Co. , Idaho, 334. Niagara series and stage, 4. Nicholas, W., on precipitation of gold, 373. Nicholson, F.. on Missouri copper mines, 314. Nickel, Arkansas, 440. Nevada, 440. Norway, 431. Ores, table and general remarks, 428, 439. Oies of igneous origin, 61, 64. Pennsylvania, 439. Niobrara stage, 5. Northampton, Mass. , lead mines, 337. North Carolina, aluminum, 407. Copper, 194. Gold, 376, 380. Limonite, 104-109. Magnetite, 160, 174. Nickel, 439. Specular ores, 155. Tin, 444. Northern States, gold deposits, 381. INDEX. 475 Northwest Territory, gold deposits, 393. Norway, chromite, 413. Nova Scotia, Clinton ore, 120. Copper pyrite, 190. Gold, 397. Oat Hill, Cal. , mercury mine, 436. Ocean as a source of ores, 33. Ogdensburg, N. J., 250. Ohio, Clinton ore, 114, 115. Limonite, 96, 107. Okanogan Co., Wash., 347. Old Dominion copper mine, Ariz., 219. Old Sterling mine. Mo., 125. Old Tenn. mine, 192. Oligooene series, 5. Oliver mine, Va. , 152. Olmstead, I., on Burden mines, 111. Oneida Co., Idaho, 327. Ontario, arsenic mine at Deloro, 412. Nickel mine, 436. Ontario mine, Utah, 329. Ontonagon copper district, Mich., 207, 209. Ophir Cafion, Utah, 275, 330. Ophir silver mine, Cal. , 353. Oppel, von on strata beds, 55. Oquirrh Mt. mines, Utah, 274. Orange Co. . N. Y. , zinc mines, 256. Orchard gneiss, 11)3. Ore deposits, classification, 54. Literature on, 74-79. Ore-minerals, 33. Oregon, geology of, 347. Gold mines, 348. Mercury, 424. Organic matter as a precipitating agent, 68. Oriskany series, 4. Orton. E., on black band ore, 108. On dolomitization, 32. Ouachita uplift, 446. Ourav Co., Colo., 287. Owvliee Co , Idaho, 35, 337. Ozark uplift, 122, 155. Pacific Ocean, 445. Pahranagat district, Nev., 338. Paleozoic group, 4. Palo Duro stage, 5. Panama manganese, 433. Panamint district, Cal., 353. Park Co., Colo., 295. Parting in a vein, defined, 49. Passaic iron belt, N. J. , 167. Patton mines. Ore. , bog ore, 90. Peale, A. C, on Montana gold de- posits, 315. Pearce mine, Ariz., silver and gold, 336. Pearce, R., Colo., gold, 306, 365. On gold with pyrite, 373. Peohin, E. C, cited, 95. PeekskiU, N. Y. , aluminum ores, 410. Magnetite, 173, 173. Penfleld, S. L., cited, 441. Pennsylvania, brown hematites, 93, 94, 101. Chromite, 414. Clinton ore, 116. Gold, 383. Lead mines, 237. Limonite, 101, 104. Mansfield ore, 131. Spathic ore, 113. Penokee-Gogebic district, Mich., 139. Penrose, R. A. F. , on Arkansas iron ores, 96. On Arkansas manganese ores, 430. On Colorado gold deposits, -304. Pentlandite, 439. Percival, on Connecticut limonite, 104. Permian series, 5. Perry Co., Penn., 108. Peru, S. A., mercury, 434. Peters, cited, 437. Phelps Co., Mo., iron ores, 133. Phillips, J. A., on scheme of classifi- cation of ore deposits, 454. Phillipsburg, Mont., 319. Phoenix copper district, Mich. , 208. Phosphorus in iron ore, 85, 183. Pictou Co., Nova Scotia, iron ore, 130. Pierre stage, 5. Pike's Peak, Colo., 403. Pilot Knob, Mo , iron ores, 155. Pima Co., Ariz., lead-silver, 379. Silver and gold, 336. Pinal Co. , Ariz. , gold and silver, 335. Pinches in a vein, 49. Pioche, Nev., 338. Pirsson, on geology of Little Rocky Mts., 333. Pitch of a fold defined, 13. Pitkin district, Colo, 394. Pittsburg iron ore group, 108. Pittsburg seam, 108. Piute Co., Utah, 333. Placer Co., Cal., chromite, 415. Magnetite, 171. Placers, 59, 70. Plateau region of Rockies, 445. Platinum, 441. 476 INDEX. Platoro, Colo., 296. Pleistocene system, 5. Pliocene series, 5. Point Oi-ford, Ore., 348. Poorman lode, Idaho, 337. Portage Lake copper mines, Mich., 307. Portage stage, 5. Port au Port Bay, Newfoundland, chromite, 416. Porter, J, B. , on Clinton ore, 130. Porter, J. A., on Colo, gold, 388. Portland mines, Cripple Creek, Colo., 305. Posepny, F., cited, 47, 376. On contact deposits, 67. On ore origin, 459. On replacement, 44. Potrillos, Mex., tin ores, 444. Potomac formation, 5. Potsdam stage, 4. Power, F. D., on classification of ore deposits, 56, 461. Pratt, J. H., on chromite, 61. On North Carolina chromite, 413. On origin corundum, 408. Presoott, Ariz., 320, Prime, F., on Siluro-Cambrian limon- ites, 94, 104. On classification of ore deposits, 451. Prometheus Mt., Nev., 339. Prosser mines. Ore., bog ore, 91. Psilomelane, 416. Puei'co stage, 5. Puget Sound, 90. Puget Sound Basin, Wash., 846. Pumpelly, R. , on classification of ore deposits, 456. On copper rock of Michigan, 209. On hematite, 133, On replacements, 44. Putnam, B. W., cited, 73. On magnetite ore, 165. Putnam Co., N. Y., iron mines, 166. Pyrite beds, 184. With copper, 189. Pyrrhotite, of igneous origin, 61, 64, 65. With nickel, 430. Pyrolusite, 416. Q Quaco Head, N. B., manganese, 433. Quaquaversal, defined, 12. Quavtzburg-Grimes Pass belt, 325. Quaternary system, 5. Queen of the West mine, Colo., 266. Quicksilver, 424. Quigley, Mont., 331. Quincy mines, Mich., 308. Quinnesec mines, Mich., 138. Quebec, chromite, 416. Copper mines, 190. Eaibl, Austria, lead-silver deposits, 44. Rainbow lode, Mont., 319. Rainier Mt., 346. Rainy River gold district, Minn. , 383. Rampart Series in Alaska, 388. Eamshorn mine, Idaho, 324. Randsburg gold mines, Cal., 351. Raritan stage, 5. Rathgeb mine, Cal., 370. RavalUCo., Mont, 331. Raven Hill, Colo., 305. Raymond & Fly mine, Nev., 338. Recent series, 5. Red Cliff, Colo., 394. Red Mt , Ala., 117. Red Mt, Kern Co., Cal., 8.53. Red Mt., Ouray Go,, Colo., 373. Red Rock, San Francisco, manganese, 431. Reese River district, Nev., banded veins, 47. Gold and silver, 339. Reich, on electrical action in veins, 53., Replacement, 33, 44, 58. Republic mine, Mich. , 85. Residual clay in a vein, 49. Residual deposits, 59, 71. Rhode Island, gold deposits, 883. Richmond, Mass., limonites, 101. Richthofen, von, on California gold veins, 365. On origin Comstock lode, 340-841. Rickard.T. A., on CaUf ornia gold, 370 On Newman Hill, Colo. , 393, Rico, Colo., lead-silver, 271. Riddle's, Oregon, nickel, 438. Rifting in granite, 13, 15. Rio Grande Co. , Colo. , 395. Rio Tinto, Spain, old timbers, 53. Rio Viento Frio, S. A., manganese 423. Ripley stage, 5. River gravels with gold, 353. Roanoke, Va., zinc ores, 349. Roaring Fork Creek, Colo., 368. Robert E. Lee mine, Colo., 263. Robinson mine, Colo., 266. Rocliester. Mont., 817. Rockbridge Co. , Va. , tin ores, 444. Rock Creek district, Idaho, 825. Rocks, classified, 6. Eruptive, 447. Magmas, 60-67. INDEX. ^Ti Rocky Mts., faults of, 30. Lead and zinc deposits, 249. Silver and gold deposits, 308. Rogers, H. D.. cited, 120. On New Jersey zinc deposits, 251. Rolker, C. M., on Silver Reef ores, 834. Ropes gold mine, Mich. , 383. Rosenbusch, H., cited, 59. Rosita, Colo., 296. Rossland, B. C, H2 896. Roth, J., on anal j'ses igneous rocks, 87. Rothwell. R. P., on Silver Reef ores, 333. Rotten limestone stage. 5. Roiibidoux sandstone, Mo., 133. Routivara, Sweden, magnetite, 6, 172, 175. Roxbury, Conn., limonite, 113. Ruby mine, Colo.. 317. Russell, I. C, on Clinton ore, 130. Russia, platinum. 441. Rye, N. Y., bog ore, 91. Sacramento Valley, Cal. , 349. Safford, J. S., on siliceous group, 96. On Tennessee limonites, 103. Saguache Co., Colo., 393. Sain Alto, Mex. , tin, 444. Salina Co. , Ark. , nickel ore, 440. Salina series, 4. Salisburv, Conn., limonites, 101. Salt Co. ."Utah, 329. San Benito Co., Cal., antimony, 410. San Bernardino Co., Cal., iron ore. 171. Sandberger, F., on derivation of ores, 34. 41. On dark silicates, 447. San Diego Co., Cal., iron ores, 171. San Emigdio, Cal , antimony, 410. Sanscre de Cristo Range, Colo., 260- 300. San .Joaquin Co., Cal., mangane.se, 421. San Juan Ml, 2s;. San Juan Co., Colo., bisfnuth, 412 Gold and silver, 287. San Luis Obispo Co. , Cal. , chromite, 415. San Miguel Co., Colo., 390. SanteFeCo., X. M., 386. Santa Rita copper district, N. M., 319. Santa Rita Mt. , N. M. , 385, Santiago, Cuba, iron ores, 186, 187. f^aucon Valley, Penn., zinc mines, 58, 3.50. SawatchMt., Colo., 363. Sohapbach, cited, 43. Schemes of classification of deposits, 448-457. Schmidt, A., on Missouri iron ores, 132, 158. On Missouri lead and zinc ores, 343, 346. On replacement, 44. Schrauf, A., on mercury deposits, 435. Schoharie stage, 5. Schuyler copper mines, N. J. , 333. Secondary alteration in veins, 50. Sedimentary rocks defined, 6. Segregation, 59, 73. Selvage in a vein defined, 49. Servia, mercury, 434. Seven Devils' district, Idaho, 333. Sevier Co., Ark., antimony, 411. Shaler, N. S., on origin of Clinton ore, 130. Shasta Co. , Cal. , chromite, 415. Shasta Mt., Cal., 349. " Shasta stage, 5. Shaw mine, Cal. , 369. Shaw Mt. district, Idaho, 335. Shear zones defined, 17, 58. Sheep Creek Basin, Alaska, 393. Sheep Mt. district, Idaho, 334. Sheerer, cited, 430. Sheet defined, 12. Shepherd Mt., Mo., 157. Sherbrooke, Quebec, 190. Siderite, genetic I'elations, 113. Spathic ore, 106-113. Sierra Co., Cal., iron ore, 171. Sierra de Mercado, Mex., hematite, 188. Sierra Nevada Range, Cal., geology of, 349, 358. Siluro-Cambrian limonites, 100-105. Silver and gold ores, analyses, 381. Deposits. 2S0. Statistics, 401. Silver Bow Basin, Alaska, 391. Silver Bow Co., Mont., 318. Silver Bow Creek, Mont., 197, 319. Silver, California, 351. Silver City, N. M., 407. Silver Cliff, Colo., 57, 296. Silver Islet, 43, 283. Silver King mine, Ariz., 335. Silver minerals, 281. Silver Plume, Colo., 306. Silver Reef, Utah, 333. Silverton, Colo., 3!)3. Silver, Washington, 347. Simmon's iron mines. Mo., 133. Simundi, H. , on gold ores, 35. Sitka, .Alaska, 392. Slickensides or slips defined, 23. 478 INDEX. Slocan gold district, B. C, 394. Smithfleld iron mine, Colo., 170. Smith, F. C, on Black Hills gold de- posits, 313. Smith, J. P., on auriferous strata, 874. Smuggler mine, Colo. . 289. Smuggler Mt., Colo., 270. Smyrna, aluminum, 410. Smyth, C. H., Jr., on hematite, 131, 134, 135. On limonites, 113. Smyth, H. L., 139. On Menominee district mines, 136, 138. On Michigan copper, 310. On Michigan iron ores, 137, 144. Snake River, Idaho, 373, 333. Snohomish Co., Wash., silver de- posits, 347, Socorro Co., N. M., gold and silver, 385. Sonora, Mex., antimony, 411. Soret's principle, 64, 171. Sources of the metals, 33, 34. South Carolina, gold deposits, 380. South Dakota, gold and silver ores, 309. ■ Lead-silver, 373. Tin, 443. Southern States, gold, 446. Pvrite under gold, 184. South"^Mt., Penn., iron ores, 166, 169. Gold belt, 378. South Park, Colo., 395. Spanish Peaks, Colo. , 395. Spathic iron ore, 113. Spenceville, Cal., Coppermine, 195. Sperry, F. L., on Algoma district, 441. Sperrylite, 438. Spurr, J. E., on Aspen, Colo., 369. On iron ores, 153. On Mercur gold deposits, 331. On Mesabi ores, 153. On Yukon Basin, 388, St. Frangois Co. , Mo. , lead and zinc, 339. St. Genevieve, Mo., copper mines, 313. St. Lawrence Co. , N. Y, , lead mines, 326, St, Louis, Mo. , nickel ores, 440. St. Mary's mine, Penn. , 179. Stannite, 445. Star district, Utah, iron mines, 180. Staten Island bog ore. 91. Steamboat Springs, Nev., 30, 35, 44, o7. Mercury mines, 427. Stehekin copper district. Wash., 222. Stein Mt., Ore., 347. Stelzner, A. W., cited, 34. Step-faults defined, 34. Sterling Hill zinc mine, N. J., 351- 357. Sterling mines, Cayuga Co., N. Y., 115. Stevens Co., Wash., gold, 347. Stevenson, J. J., cited, 50. Stibnite, 410. Sioickeen river, Alaska, 394: Stobie nickel mine, Ont., 436. Stokes Co., N, C, iron ore, 170, Storey Co, , Nev, , silver and gold, 340. Storms, W, H,, on Alvord mine, Cal,, 370. Stratum defined, 6. Stratigraphy of aui'if erous strata, 374. Stream tin, 443. Strike-faults, 31, 25. Sub-carboniferous series, 5. Succession of minerals in an igneous rock, 83, 34. Sudbury, Ont., Can., 63. Cobalt, 438. Iron, 184. Nickel 439, 481. Sullivan Co., N. Y., lead deposits, 338, Sulphur Bank, Cal,, mercury, 44, 437. Sulphur in iron oi-es, 85, 86. Sulphur in rocks, 37. Sumdum Bay, Alaska, gold deposits, 393 SimimitCo., Colo,, 394, Lead-silver, 366, Summit Co., Utah, lead-silver, 375. Summit district, Colo, , 45, 53, Sunrise copper mines, Wyo., 332, Sweden, lake ores, 92, Sweden, magnetites, 175. Sweet Grass Hills, Mont,, 333. Sweetwater Co., Wyo., 308. Swells in a vein, 49. Syncline defined, 11, 17. Taberg, Sweden, iron ore, 60, 175. Takii mines, Alaska, 398. TalahCo.. Idaho, 334. Tamarack copper mine, Mich., 308. Tarr, R. S. , on Cape Ann granite, 18, 14. On classification of ore deposits, 459, Telegraph lead-silver mine, Utah, 375. Teller Co., Colo., 300. Telluride, Colo., 388. Tellurides in gold quartz, 363. Temescal tin mine, Cal., 443. INDEX. 479 Tern Pahute district, Nev., 338. Teu-mile district, Colo., 366, 294. Tennessee, Clinton ore, 114, 116. Copper, 194. Lead zinc, 349. Limonite, 96, 103. Manganese, 430. Tennessee mine, Polk Co., Tenn., 193. Tenny Cape, Nova Scotia, 433. Terrace series, 5. Terrane defined, 6. Terry Peak, S. D., 311. Tertiary system, 5. Teton Co., Mont., 321. Texas, copper ores, 204, 334. Limonite, 97, 98. Mercury, 424, 438. Tin, 444. Texas mine, chromite, 415. Texas, Penn., nickel ore, 439. Thies-Hutchins antimony mines, Nev., 411. Three Rivers, Que., bog ore, 90. Thunder Bay, Can., 284. Tilly Foster iron mine, N. Y., 166. Tilt Cove, N. F., nickel ore, 439. Tin, concluding remarks, 445. Deposits, 69, 70. Veins, 73. Tin Cup, Colo., 394. Tintic district, Utah, copper mines, 321. Lead-silver mines, 375. Tioga Co., Penn., 131. Titanif erous magnetite, 160, 165. In the Adirondacks, 171. In Canada, 173. Colorado, 174. Minnesota, 174. New Jersey, 173. North Carolina, 174. Norway, 173. Sweden, 173. Virginia, 171. Wyoming, 171. Titanium in iron ores, 85, 86. Titcomb, H. A., cited, 352. Tombstone, Ariz., 43, 336. Torrington, Conn., nickel ores, 430. Tower, G. W., on Butte copper ores, 197. Tower. Mich., 85. Toyabe Range, Nev., 339. Trail Creek district, B. C, 394. Trail of a fault, 23. Treadwell irdne, Alaska, 390. Trenton series and stage, 4. Triassic system, ."). Trigg Co., Ky., 95. Trotter zinc mine, N. J. , 352. Tucson, Ariz., 336. Tuolumne Co., CaL, 863. Turner, H. W., California gold gravels, 359. Tuscaloosa stage, 5. Tuscarora district, Nev. , 340. Tybo, Nev., 338. Tyrrell, on Alaska gold gravels, 393. Tyson, I,, Jr., on chromite market, 414. U Ueberroth zinc mine, Penn., 350. Uintah Mt.. Utah, 335. Uinta stage, 5. Ulster Co., N. Y., lead deposits, 239. Limonites, 111. United States Antimony Co., Phila., 411. United States, geological review of the, 8-10. Topography of the, 7, 8. Magnetite sands, 181. United Verde copper mine, Ariz., 320. Utah, antimony, 411. Copper, 334. Geologv, 338. Gold and silver, 329. Limonite, 100. Mercury, 424. Silver-bearing sandstone, 68. Utica stage, 4. Vadose circulation, 27. Vanadium distribution, 36. Van Diest, P. H., on Boulder Co., Colo., 306. Van Dyck, F. C. , analysis by, 254. VanHise, C. E., cited, 44. On classification of Michigan ores, 133. On joints, 14. On Marquette district, 129. On Penokee district, 139. On zones of fracture, 35. Van Wagenen, T. F. , cited, 53. Veins, changes in filling, 50. Methods of filling, 39. Swells, 49. Vermilion district, Minn., 134. Lake, iron mines, 144-146. Vermont chromite, 416. Gold, 383. Iron, 184. Lead, 227. Limonite, 100. Manganese, 418. Vershire, Vt., copper ore, 184, 190, 480 INDEX. Verticals in gold mines, Black Hills, 312. Vicksburg stage, 5, Victor mines, Colo. , 385. Virginia, Clinton ore, 114, 116. Gold deposits, 381. Lead and zinc, 247. Limonite or brown hematite, 87- 114. Magnetite, 169, Manganese, 418. Virginia City, Mont., 316. Vivianite in bog ore, 89. Vogelsberg, Germany, aluminum, 407. Vogt, J. H'. L. , on chromite, 413. On ore deposits, 61-65. On nickel ores, 484. On sulphides of iron, 185. Vuggs of a vein, 48. W Wabner, R., cited, 55. Wadsworth, M. E., on iron ores, 137, 135. On classification of ores, 458. On copper ores, Keweenaw, 205. On Marquette district, 128. On origin of copper ores, 211. Wahnapitae Lake nickel mines. Can. , 436. AValcott, C. D., on'fossilsof Montana, 315. Walker, T. L., on nickel ore, 437. Wallingf ord, Vt. , manganese ore, 418. Wardner, Idaho, lead-silver mines, 274. War Eagle mine, B. C, 397. Wasatch Mt., Mont., 314. Utah, 180, 274. Wasatch stage, 5. Washington Co., Mo., lead and zinc mines, 239. Washington copper deposits, 222. Geology, 346. Silver, 347. Washoe Co., Nev., gold and silver mines, 340. Watei-, underground, 26-32. Waukon, Iowa, limonite, 98. Wawa Lake gold deposits, 385. Wayne Co., N. Y., Chnton ore, 115. Waynesburg coal seam, 107. Webster, N. C, nickel, 439. Weed, W. H. , on copper deposits, 197. On gold deposits, Montana, 315. On sinters, 68. On vein formation, 38. Weissenbach, von, cited, 47, Weissenbach, von, on scheme of classification of ore, 448. Wells, Professor, cited, 441. Wendt, A., mineral veins, 5t. Werner, cited on his epoch, 55. Westport, N. Y., magnetite, 173. Weston mine, N. Y., 162. West Stockbridge, Mass., limonite, 101. West Virginia, Clinton ore, 114. Limonite, 107. Red hematite, 121. Wet Mt. Valley, Colo., 396. Wheatfield raine, Penn. , 179. Wheatley lead mine, Penn., 327. White Oak gold district, N. M., 385. White Pine Co., Nev., 338. White River stage, 5. White Quail mine, Colo. , 367. Whitney, J. D., on California grav- els, 356. On origin Michigan iron ore, 135. On Missouri ores, 158. On lead ores, 336-43. On Mother lode, Cahfornia, 364. On scheme of classification of ores, 453. On Seaweed, 68. Wickes, Mont. , lead-silver mines, 273. Wilhams, G. H., cited, 138. On chromite, 415. On manganese, 430. Willis, B., cited, 178. Willow Creek, Idaho, 325. Wiltsee, E., on Half Moon mine, Nev. 338. Winchell, H. V. , on Rainy Lake dis- trict, 384. Winchell, N. H,, and H. V,, on Pen- okee iron ore, 150. Wind River stage, 5. Winslow, A., Missouri lead and zinc mines, 330-344. On Tin, 444. Winston, Mont., 319. Wisconsin, Clinton ore, 114. Lead and zinc mines, 68, 333. Wisconsin Island, 9. Wolff, J. E,, on Hibernia magnetite, 168. On New Jersey zinc deposits, 352. Woodman, J. E, , Nova Scotia gold, 399. Wood River mines, Idaho, lead-silver, 373, 337. Woods mine, chromite, 414. Woodworth, J. B., on joints, 15. Worthington nickel mine, 436. Wyoming, copper mines, 333. Geology of, 308. INDEX. 481 Wyoming iron mines, 171. Tin ores, 443. Wythe Co., Va., zinc, 347, 348. Yak River, Mont., 332. Yakima Co., Wash., placer mines, 347. Yakutat Bay, Alaska, gold sands, 849. Yavapai Co., Ariz., gold, silver ores, 335. Yellow Jacket mines, Idaho, 334. Yogo Gulch, Mont., aluminum, 410. York Co., N. B., antimony, 411. York Co., Penn., iron ores, 101, 179. Yukon Basin, Alaska, 393. Yukon silts, 389. Yuma Co., Ariz., 335-837. Zinc minerals, 350. Analyses, 354. Statistics, 359. Zone of fracture in the earth, 35. Of oxidized ores, 50-53. 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Introductory — Mistakes in Mining. What Constitutes a Mine. Rock-forming Minerals and Rocks. Physical Character of Mineral Deposits. Origin of Veins. Filling of Mineral Veins. Influence of Rocks on Vein Filling. Mineral Deposits Other than Veins. Prospecting. II. III. IV. V. VI. VII. VIII. IX. CHAPTER. X. Making Locations. XI. Patents to Mining Ground. XII. Early Development of Mines. XIII. Ores. XIV. Useful Earthy Minerals, etc. XV. Coal. XVI. Gold Gravel Deposits. XVII. Water and Its Measure- ment. XVIII. Artesian Wells. Useful Tables. Good Books of Reference. IN TWO STYLES-Library Edition, Cloth, 12mo, - ■ ■ $2.00 Poclcet Edition, Flexible iVIorocco Cover, Special Paper, 2.50 The Engineering & Mining Journal, (INCORPORATED.) 261 BROADWAY, NEW YORK. SOME SPECIALLY VALUABLE BOOKS ON Mining and Metallurgy Metallurgy of Steel, H. M Howe - llO.OO Ore Dressing and Concentration. R. H. Richards (in press) - ''•00 Metallurgy of Lead, H O. 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