^,/^f^\/ "o^-^^-/ \/^^\/ V^^*/ \' <^. .^^ r .^'*^% ^^ \ '-^^-^.^'^ '-^f^' /\ •,^- **'\ .: 0' 'b V -^ '\ ^bv" ':^o^ ■!?>'' * ^'J> * ^^' c^' . > ^^,^^ •<"<;^ ^. *»«»' o, o, * C" • ^ •v^O^ ■••••,o*\.-..V"^-''^<^ v-J^^ , -?=> .0 ^--o'^ .-^^ . "<^. c-^" ♦'^^M^"'. ^^. .^ ■ Z-^-^^-- •^- .^■^^ .' «H q. .0 0°"°^ o Bureau of Mines Information Circular/1986 Placer Gold Sampling in and Near the Chugach National Forest, Alaska By Robert B. Hoekzema and Steven A. Fechner UNITED STATES DEPARTMENT OF THE INTERIOR Information Circular 9091 It Placer Gold Sampling In and Near the Chugach National Forest, Alaska By Robert B. Hoekzema and Steven A. Fechner UNITED STATES DEPARTMENT OF THE INTERIOR Donald Paul Model, Secretary BUREAU OF MINES Robert C. Norton, Director As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. This includes fostering the wisest use of our land and water resources, protecting our fish and wildlife, preserving the environment and cultural values of our national parks and historical places, and providing for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resovirces and works to assure that their development is in the best interests of all our people. The Department also has a major responsibility for American Indian reservation communities and for people who live in island territories under U.S. administration. Library of Congress Cataloging-in-Publication Data Hoekzema, Robert B. Placer gold sampling in and near the Chugach National Forest, Alaska. (Information circularAJnited States Department of the Interior, Bureau of Mines ; 9091) Bibliography: p. 42 Supt. of Docs, no.: I 28.27: 1. Giold ores- Alaska— Chugach National Forest Region. 2. Placer deposits-Alaska- Chugach National Forest Region. 3. Chugach National Forest (Alaska) I. Fechner, Steven A. 11. Title. III. Series: Information circular (United States. Bureau of Mines) ; 9091. TN3»&Jid^ [TN413.A6] 622 s [553.4'1 '097983] 86-600059 CONTENTS 111 Page Abstract 1 Introduction 2 Previous work 2 Land status within the Chugach National Forest 2 Acknowledgments 4 Mining history and production 4 Geology and mineralization 4 Valdez Group 7 Orca Group 7 Younger Tertiary rocks 7 Tertiary plutons 7 Present investigations 7 Literature research 7 Field investigations 7 Analjrtical methods 8 Results 8 Page T5rpes of placer deposits 8 Origins, characteristics, and distribution of placer gold 9 Placer gold mineral development potential and resource estimates 9 Criteria used to assess placer gold mineral development potential of the Chugach National Forest 9 Resource estimates 10 Conclusions 10 References 11 Appendix A.— Placer deposit and sample data .... 12 Appendix B.— Placer deposit descriptions 30 Appendix C— Summary of placer gold deposit types 40 ILLUSTRATIONS 1. Index map of Alaska showing Chugach National Forest 2 2. Land status map of Chugach National Forest 3 3. Eight-inch suction dredge used to recover gold from Ingram Creek 5 4. Backhoe-fed trommel washing plant used to recover gold from Mills Creek 5 5. Geologic map of Chugach National Forest 6 6. Typical channel sample used for evaluating placer deposits 8 A-1. Index map for figures A-2 through A-13 17 Placer deposit and sample location maps: A-2. Copper River Delta area 18 A-3. Copper River area 19 A-4. Scott Glacier area 20 A-5. Tasnuna River area 21 A-6. Orca Bay area 22 A-7. Valdez area 23 A-8. Unakwik Inlet 24 A-9. Girdwood-Port Wells area 25 A-10. Resurrection Creek-Canyon Creek area 26 A-11. Kings Bay area 27 A-12. Kenai Lake area 28 A-13. Puget Bay area 29 TABLES 1. Estimated placer gold production and identified resources for selected drainages A-1. Sample results for placers PI through P102 See also appendix B. 4 13 IV ft gpm hp h in lb m.y. oz foot gallon per minute horsepower hour inch pound million years ounce iVIATIONS USED IN THIS REPORT oz/h ounce per hour oz/yd* ounce per cubic yard pet percent ppm part per million ppt part per thousand yd« cubic yard yd^/d cubic yard per day yr year PLACER GOLD SAMPLING IN AND NEAR THE CHUGACH NATIONAL FOREST, ALASKA By Robert B. Hoekzema^ and Steven A. Fechner^ ABSTRACT The Biireau of Mines and U.S. Geological Survey completed a 4-yr (1979-82) mineral appraisal of the Chugach National Forest (CNF), AK. This report summarizes the Bureau's placer gold studies in the CNF. Placer mining from the mid-1890's through 1982 produced an estimated 133,800 oz of gold, of which two-thirds was produced prior to 1920. As much as 6,800 oz of placer gold was produced from 1979 to 1982. Most production came from Crow, Canyon, and Resurrection Creeks. Five types of placer gold deposits were identified in the CNF: (1) alluvial placers, (2) bench placers, (3) eluvial placers, (4) glacial placers, and (5) marine placers. Placer sampling indicated a potential for gold production from alluvial and bench placers associated with historically mined drainages such as Crow, Canyon, Resurrection, Sixmile, and Mills Creeks and from unmined drainages including the Avery, Kings, Snow, Copper, and Tasnuna Rivers and several smaller streams throughout the CNF. Results of fineness tests indicated that gold from the CNF ranges from 455 to over 950 fine. Subsequent investigations in drainages with anomalous placer sample values also identified previously unknown lode mineralization. 'Supervisory physical scientist. 'Physical scientist. Alaska Field Operations Center, Bureau of Mines, Anchorage, AK. INTRODUCTION A mineral resource investigation of the CNF (fig. 1) was conducted from 1979 to 1982 by an interagency team made up of personnel of the U.S. Geological Survey (USGS) and the Bureau of Mines. The investigation was initiated under the Roadless Area Review and Evaluation (RARE II) program (Public Law 94-588). The USGS compiled and evaluated data on regional geology, geochemistry, and geophysics. The Bureau compiled data and conducted field investigations of mines, prospects, mineral occurrences, and areas of mineralization. Reports discussing geology and lode mineralization are available from the Bureau (If and USGS (2). This report summarizes the results of the Bureau's placer program, which included the collection and processing of 420 bulk placer samples, fineness determinations for 125 samples, and classification of placer deposits into 5 categories. PREVIOUS WORK The earliest works describing the placer gold deposits of the CNF were published by the USGS (3-5). Moffit (6) and Johnson (7) were the first to publish detailed descriptions of the placer gold deposits in the Hope-Sunrise and Valdez areas. Martin and others (S), Park (9), and Tuck {10) published reports on the geology and mining on the Kenai italic numbers in parentheses refer to items in the hst of references preceding appendix A. Peninsula and nearby areas. Cobb (11) published a map on placer deposits of Alaska. Tysdal (12) published a map showing the placer deposits of the Seward and Blying Sound quadrangles on the USGS 1:250,000 topographic map series. Hoekzema (13) and Fechner and Meyer (14) discussed the results of 1980 and 1981 Bureau placer sampling studies in the CNF. Sherman and Jansons (15) discussed the economic feasibility of placer mining in the CNF. LAND STATUS WITHIN THE CHUGACH NATIONAL FOREST The CNF encompasses portions of the Anchorage, Nelchina, Nizina, Prince William Sound, Yakataga, Hope, and Seward Mining Districts (16). Federal, State, and private lands (including native regional corporation selections) are present within the CNF (fig. 2). State land is located near Seward, Kenai Lake, Whittier, Valdez, and Cordova. Private land is located in the cities of Cordova, Valdez, and Seward; along the coast from Cordova to Valdez; and on Latouche, Evans, Knight, and Chenega Islands. Private inholdings are also scattered throughout the CNF, with the majority on the Kenai Peninsula. The remaining land is managed by the U.S. Department of Agriculture (USDA), Forest Service. Barn ..M.^*^- • Chugach National Forest Al«ution FIGURE 1. Index map of Alaska showing Chugach National Forest. 3 3 • - M S o IL a c o n z u CB o Q. B E « C (B -I cii ui oc 3 o iE ACKNOWLEDGMENTS Niiinerous miners on the Kenai Peninsula cooperated with Bureau efforts during the study. The authors would especially like to thank the following for their contributions of data, time, and resources, which greatly helped to improve the study: Edward Ellis, Crescent Creek miner; George and Lillian Zimmer, Milo Flothe, and Robert Kelley, Quartz Creek miners; Al Johnson, president of Hope Mining Co., Resurrection Creek; Marty Marht, Falls Creek miner; Marvin Self, Mills Creek miner; Donald Goodman, Colorado Creek miner; Doug Keating, Cooper Creek miner; Barney and Cynthia Toohey, Crow Creek miners and operators; and Gary McCarthy, David Cavanaugh, and Gene Backus, Crow Creek miners. MINING HISTORY AND PRODUCTION The earliest recorded attempts to identify mineral resources in the CNF were made by Russian explorers in the mid-1800's. Peter Doroshin, a mining engineer sent by the Russian- American Co., reported finding widespread auriferous gravels along the Kenai River system in 1848, but was apparently unsuccessful in locating commercial quantities of gold. Grold placers were discovered on Mineral (P-25),'' Mills (P-63), Canyon (P-67), Resurrection (P-71), and other creeks in the 1800's and 1890's. Many prospectors originally bound for the Klondike goldfields were attracted by the gold discoveries in the Prince William Sound-Kenai Peninsula area. Evidence of past mining, such as wingdams, hydraulic pipes, mills, and workings, is common throughout the CNF. Barry (17) summarized the history of mining on the Kenai Peninsula. The U.S. Bureau of Land Management (BLM) mining claim report dated October 19, 1984 (18) indicates that there are over 2,420 current placer claims in the CNF. Placer gold production figures for the CNF were 'Numbers with letter prefix in parentheses reference placer gold deposits shown in appendix A maps and described in appendix B. compiled from records maintained by the Bureau and the U.S. Mint, USGS reports, smelter returns, and company data. Placer gold production in the CNF has been limited mostly to the Kenai Peninsula and Turnagain Arm drainages. The estimated production from these drainages is 133,800 oz Au (table 1), of which 67 pet was produced prior to 1920. There was a resurgence of mining activity when the price of gold rose from $20.67 to $35.00 per ounce in 1934, but activity decreased dramatically with the advent of World War IL A rise in the price of gold in the 1970's led to renewed placer mining activity and gold production. Approximately 35 gold placer operations, with a combined production of up to 6,800 oz, were intermittently active during the 1979-82 mining seasons. The operations ranged from 4- to 8-in suction dredges (fig. 3) and hand placer operations capable of processing 10 to 15 ydVd to backhoe-dozer- washing plant operations capable of processing as much as 2,000 ydVd (fig. 4). Numerous recreational miners also work gold-bearing gravels along the streams, but their aggregate production probably does not exceed 100 oz/jt Au. GEOLOGY AND MINERALIZATION Most of the CNF is underlain by tightly folded and ex- tensively faulted metasedimentary rocks of the Cretaceous Valdez and Eocene Orca Groups. Younger Tertiary sedi- mentary rocks are exposed in the easternmost part of the CNF. Tertiary plutons are scattered throughout. The general geology of the CNF is shown in figure 5. Table 1.— Estimated placer gold production and Identified resources for selected drainages on Kenai Peninsula and Turnagain Arm, by decade Placer Drainage Estimated gold production , oz Identified number' Pre-1910 1910-19 1920-29 1930-39 1 940-49 1950-59 1960-69 1970-79 1980-82 Total resources, 103 yd3 P-43 Crow Creek 23,000 25,000 8,000 5,000 2,000 1 ,500 1 ,000 300 300 500 250 50 500 5,000 10,000 3,000 500 NA 500 500 1,000 100 200 100 50 500 8,000 3,000 1,000 100 1,000 NA NA NA NA NA NA NA 50 5,000 2,000 8,000 500 1,000 NA 100 NA NA NA NA NA 50 500 100 1,000 100 NA NA NA NA NA NA NA NA NA 500 500 1,000 1,000 NA NA NA NA NA NA 100 NA NA 100 100 1,000 100 NA NA NA NA NA NA NA NA NA 100 200 2,000 150 1,000 100 100 50 100 Some 100 NA 50 300 800 1,800 50 500 150 50 50 300 50 100 350 600 42,500 41,700 26,800 7,500 5,500 2,250 1,750 1,400 800 750 650 450 1,750 1,000 P-67, P-63 . P-71 P-61 P-70 Canyon-Mills Creek . . . . Resurrection-Palmer Creek Lynx Creek Bear Creek 2,000 2,000 1,000 1,000 P-68 P-69 Gulch-East Fork Creek . Sixmile Creek . . . ND 3,000 P-94, P-95 . P-74 Cooper-Stetson Creek . . Quartz Creek ND 750 P-56 Bertha Creek ND P-62 Silvertip Creek 1,000 P-90 Crescent Creek Others (15 areas) Total ND ND 67,400 21,450 13,150 16,650 1,700 3,100 1,300 3,950 5,100 133,800 NAp NA Not available. NAp Not applicable. ND Not determined. 'From maps in appendix A. FIGURE 3. Eight-inch suction dredge used to recover gold from Ingram Creek. FIGURE 4. Backhoe-fed trommel washing plant used to recover gold from Mills Creek. O o o 2 > o 3 • U..E « s o U. T5 c o u n o o. « E o O) o o o O UJ 3 O VALDEZ GROUP YOUNGER TERTIARY ROCKS The Valdez Group crops out in the western and northern portions of the CNF as an arcuate-shaped band of rocks and consists primarily of a sUghtly metamorphosed, steeply dip- ping, marine clastic (flysch) sequence. Plafker, Jones, and Pessagno (19) speculate that these rocks accreted to the southern Alaska mainland during late Cretaceous and early Tertiary time. The Valdez Group hosts small, high-grade gold lodes. Streams draining this unit commonly contain gold-bearing gravels. All placer gold production in the CNF recorded prior to this study occurred from streams draining rocks of the Valdez Group. ORCA GROUP The Orca Group crops out in the central portion of the CNF as an arcuate-shaped band of rocks located immedi- ately east and south of the Contact Fault, which separates it from the Valdez Group (fig. 5). Orca Group rocks are similar in appearance and composition to those of the Valdez Group, but tend to contain more mafic volcanics. Plafker, Jones, and Pessagno (19) speculate that the rocks accreted to the southern Alaska mainland during the Paleogene epoch. The Orca Group rocks host numerous copper deposits and a few small, widely scattered gold lodes. Although historically no placer gold mines have been developed in Orca terrane, a few placer samples containing anomalous values of gold O0.0005 oz/yd^ Au) were collected during the 1979-82 investigations from streams draining the group. Tertiary rocks, younger than the Orca Group, are pres- ent at Kayak Island and areas east of the Copper River. Younger rocks consist of unmetamorphosed siltstones, claystones, shales, sandstones, and basalt. The younger Ter- tiary strata include the Yakataga, Redwood, Poul Creek, Tokun, Kulthieth, and Stillwater Formations, plus un- divided sedimenteiry and volcanic rocks that were deposited on the Orca Group and its associated plutonic rocks diu-ing periods of marine transgression and regression (20). The younger Tertiary sedimentary rocks contain known deposits of subbituminous coal, oil, and gas. However, re- cent exploration has not resulted in the discovery of com- mercial quantities of hydrocarbons. TERTIARY PLUTONS Tertiary plutonic rocks were emplaced during two major and one minor intrusive episodes (2). On the basis of potassium argon dating, major episodes occurred at 50 to 53 m.y. and 34 to 36 m.y. (2). Older plutons are generally medium-grained biotite and/or hornblende-biotite granite. Younger plutons, which occur in the western portion of the CNF along the Orca- Valdez contact, have multiple phases and range widely in composition from granitic to gabbroic. A minor episode of plutonism is represented by a 6-m.y.- old dacitic plug at the southern tip of Kayak Island (2). Lode gold mineralization in Valdez Group rocks is associated spatially with Tertiary plutons at many locations in the CNF. Streams draining these areas characteristically contain gold-bearing gravels and one. Crow Creek (P-43), has been the largest placer gold producer in the CNF. PRESENT INVESTIGATIONS Bureau studies of placer mineralization in the CNF began in 1979 and included literature research and related data compilation, a 4-yr field program, and evaluation of the data. LITERATURE RESEARCH A literature search and compilation of references were made using the following sovu-ces: USGS (including a review of historical files in Menlo Park, CA), Bureau files (including Minerals Availability System and Mineral Industry Loca- tion System files), U.S. Forest Service, State of Alaska, and mining companies that were active in the study area. Claim records were obtained and updated using the BLM (18) and State of Alaska MinFile reference systems (21). Additional information was obtained from interviews and cor- respondence with miners and individuals knowledgeable about the geology, mining history, and mineral development of the area. Much of the above information, together with recent data obtained by the Bureau and the USGS, has been placed in Bureau files that have been established for known mines, claims, and prospects in the study area. FIELD INVESTIGATIONS Field investigations of the CNF commenced in 1979 and continued during the 1980, 1981, and 1982 field seasons. Sluicing, hydraulic concentration, panning, and suction dredging techniques were used to collect 420 placer samples. The best available trap sites were sampled whenever possible. The usual sampling procedure consisted of hand digging a pit and processing 0.1 -yd* increments of gravel through a portable aliuninum mini sluice box or hydraulic concentrator or by panning. The sluice box measured 34 in long by 10 in wide and had 3/8-in-high transverse riffles resting on expanded metal on indoor-outdoor carpeting. Sixteen-inch-diameter pans were used. These recovery devices were used to process recent alluvial deposits adja- cent to the stream channels. The hydravilic concentrator con- sisted of a small grizzly attached to an aluminum mini sluice similar to the one described above. Water was pumped to the concentrating unit by a 125-gpm-rated pump coupled with a 3-hp engine. The concentrator was used to process bench gravels up to 150 ft from a stream. Wherever possible, channel samples of gravels were taken from sur- face to bedrock (fig. 6). Some bedrock was included in the lowermost segment of each channel sample whenever possi- ble. The efficiency of gold recovery using these techniques varied, depending upon the size and shape of the gold, the clay content of the gravels, and processing parameters such as rate of flow and gradient of the sluice box, but it generally exceeded 80 pet, based upon tests of tailings. Seventy -five 3-in suction-dredge samples were collected to evaluate gravel deposits in active stream channels. Suction-dredge sampling is most successful during periods FIGURE 6. deposits. Typical cliannel sample used for evaluating placer of low water. This method was of limited use during the 1980 and 1981 field seasons due to unusually long periods of high water. Most of the samples were collected in the spring of 1982 during low- water conditions. The efficiency of gold recovery using the suction-dredging technique is highly variable. The method was used to obtain quick semi- quantitative estimates of the placer gold development poten- tial of the streams tested. Each sample was collected over a period of 0.5 to 1 h. Sample volumes varied from approx- imately 0.25 to 0.75 yd*, depending on the nature of the material sampled. An attempt was made to reach bedrock during each sampling effort. Bulk placer sampling combined with field processing is a viable method of testing for placer mineralization. Ad- vantages include the following: 1. Results are quickly available. Immediate decisions can be made as to whether additional evaluation is war- ranted. (Lode sources of mineralization were successfully identified in the CNF in a followup study.) 2. Samples are obtained at greater depths, and are of larger volume, than samples collected for stream-sediment or panned-concentrate analysis; therefore, bulk samples are likely to be more representative. Bulk samples are espe- cially useful for evaluating short, steep, youthful drainages in which heavy minerals are not readily concentrated. 3. Cuts made for bulk samples allow samplers to ex- amine the surficial geology of the deposits in detail. ANALYTICAL METHODS Concentrates recovered from the sluices were hand panned to retain only the gold and heavy minerals, which were sent to the Bureau's Alaska Field Operations Center in Anchorage for further processing. Free gold coarser than 0.01 in diam was separated from the concentrate by a 5-in magnet to remove the magnetic portion, and a blower brush was used to separate the remaining material from the gold. Finer grained gold was recovered by amalgamation. The gold and heavy-mineral concentrate were visually examined using a microscope and ultraviolet light to identify the heavy minerals and note any unusual characteristics of the gold. Gold from 324 samples was weighed, and gold from 129 samples was sent to the Bureau's anal5i;ical laboratory in Juneau for semiquantitative multielement X-ray fluorescence spectrographic analysis for trace elements and/or fire assay to identify fineness. 4. Large numbers of processed samples can be transported from remote areas by helicopter, whereas only one or two 300 to 400-lb unprocessed bulk samples can be carried at one time by most helicopters. 5. Because much greater amounts of gravel are pro- cessed for bulk samples than for pan concentrates, larger quantities of gold are available for further laboratory analysis. RESULTS The Bureau's placer evaluation of the CNF consisted of (1) bulk sampling of most of the stream drainages, (2) classification of the types of placer deposits, (3) evaluation of the origin, characteristics, and distribution of placer gold, and (4) determination of the placer gold development poten- tial of each stream drainage sampled. TYPES OF PLACER DEPOSITS Gold placer deposits within the CNF can be classified into five categories: (1) alluvial, (2) bench, (3) eluvial, (4) glacial, and (5) marine. General characteristics, production history, and examples of eadi tjT)e of placer deposit are sum- marized in appendix C. Most of the gold from the CNF has been produced from alluvial placers, with less production from bench deposits. Eluvial and glacial placers have pro- duced only minor amounts of gold, but have potential for future development. Both deposit types contain disseminated gold that may be further concentrated by alluvial processes. Marine placers have potential for relatively large-scale development. Detailed descriptions of the major producing drainages and other areas with placer gold development potential are given in appendix B. ORIGINS, CHARACTERISTICS, AND DISTRIBUTION OF PLACER GOLD Placer gold in the CNF is believed to have originated by erosion and fluvial concentration of numerous small high-grade epigenetic gold lodes in Valdez Group metasedimentary rocks. Bedrock in the region has been ex- tensively eroded during at least five periods of Pleistocene glaciation (22). Gold placers have been developed during preglacial and interglacial stages as well as since the last glacial advance. The preservation of preglacial and in- terglacial placers was dependent largely upon their loca- tion relative to subsequent glacial scour. Several deposits of this type, recognized by their relatively high degree of compaction and cementation, have been identified in the Girdwood and Kenai Peninsula areas at Crow Creek (P-43), Mills Creek (P-63), and possibly Quartz Creek (P-74). The time elapsed since the last glacial stage and minor postglacial advances has been insufficient to allow the development of large high-grade placer deposits in the CNF such as those found in interior Alaska. Most streams are actively downcutting due to isostatic rebound. Portions of many drainages are characterized by steep narrow canyons with abundant falls and cascades. Past production has come mostly fi-om small, occasionally high-grade placers in cur- rent stream valleys. Placer gold in the CNF is generally fine-grained (<0.1 in diam) and flaky. However, coarser gold, including nug- gets weighing as much as several ounces, has been recovered from Crow (P-43), Gulch (P-68), and Bear (P-70) Creeks. A total of 129 samples of gold flakes and nuggets were tested for fineness (appendix A). Results indicated that the gold ranged from 455 to over 950 fine, with the balance of the samples ranging from 770 to 850 fine. Silver, copper, and traces of other elements made up the remainder of the fineness values. Gold-to-silver ratios calculated for gold recovered fi-om placer samples collected in the CNF ranged fi"om 0.8 to 492.5 and are listed in appendix A along with the samples' respective gold, silver, and base metal contents. Preliminary data suggested that gold fineness increases with distance from soiirce, as does the gold-to-silver ratio. Additional work is needed to relate placer gold deposits to specific source area(s) and to determine whether gold-to- silver ratios can be related to distance from source. Grold samples collected from several drainages, in- cluding Quartz (P-74) and Cooper (P-94) Creeks, have variable gold contents. Many placer samples examined under the microscope appear to contain more than one t5T)e of gold on the basis of color and shape. The data suggest multiple source areas of gold in some of the drainages. The locations of all historically mined drainages, together with those previously not known to have placer gold potential, are shown in figures A-1 through A-13 of appendix A, and these drainages are described in appen- dix B. Bulk placer sampling methods were highly effective in identifying high-grade (M).02 oz/yd^ Au) placer deposits on historically producing streams such eis Crow (P-43), Mills (P-63), Canyon (P-67), Sixmile (P-69), Quartz (P-74), Cres- cent (P-90), and Cooper (P-94) Creeks. Samples from these creeks contained fi*om 0.002 oz/yd^ Au to more than 1 oz/yd^ Au. Samples collected from several drainages previously not known to have placer gold potential contained placer gold values ranging from 0.002 to 0.15 oz/yd^ Au. These drainages were the Copper River (P-2), Tasnuna River (P-6), Marshall Glacier (P-8), Bench Creek (P-11), Brown Creek (P-14), Port Fidalgo (P-17), Silver Lake (P-22), Salmon Creek (P-23), Northwest Fork of Coghill River (P-32), an unnamed glacial drainage (P-33), Avery River (P-36), Siwash Bay Creek (P-37), and Kings River (P-80 and P-81). The presence of placer gold in a drainage may reflect nearby lode gold sources. Placer data suggests the presence of three mineralized belts in the CNF. Two of the belts strike north-northeast and occur as limonite-stained units in the Valdez Group cut by numerous felsic dikes, sills, and sulfide- bearing quartz veins. One belt extends northeast from the toe of Wolverine Glacier along both sides of the Kings River to Blackstone Glacier. The second was traced 12 miles northeast from Davis Lake to the headwaters of Unakwik Inlet. The third belt strikes east-west and extends from Miners Bay on the west to the headwaters of the Bremner River on the east. Portions of these areas have recently been exposed by retreating glaciers, so they were incompletely prospected during the heavy exploration period of the early 1900's. PLACER GOLD MINERAL DEVELOPMENT POTENTIAL AND RESOURCE ESTIMATES Appendix B summarizes the geology, mining history, and placer gold development potential of 102 drainages in the CNF. Based upon the criteria described below, 44 drainages have moderate or high mineral development potential for placer gold production. Criteria Used To Assess Placer Gold Mineral Development Potential Grades are described as follows: Highly anomalous-Recovered values higher than 0.005 oz/yd' Au Anomalous-Recovered values from 0.0005 to 0.005 oz/yd* Au Background-Recovered values less than 0.0005 oz/yd' Au Mine size and grade assumptions used for resource assessments were as follows: Small (includes suction dredges)-<500 ydVd processed; grade->0.015 oz/yd' Au Medium-500 to 2,000 yd^/d processed; grade->0.010 oz/yd^ Au Large->2,000 yd'/d processed; grade-0.007 oz/yd* Au The three categories of development potential used in appendix B are explained below. High Development Potential Grade. -Highly anomalous samiples collected and/or cur- rent production indicates a high probability that minable grades exist. i?eseri;es. -Established; or sampling indicates geologic conditions offer a high probability of establishing reserves to supply a mine of given size. Study recommendations.-Site-specific evaluation in- cluding strong recommendation for drilling and/or pit sampling. Excellent chance for identifying a minable reserve. 10 Moderate Development Potential Grade. -A single highly anomalous sample and/or anomaloiis samples indicating possibility that minable grades exist. Reserves. -No established reserves. Geologic conditions are conducive for establishing enough reserves to supply mine of given size. Study recommendations. -Additional reconnaissance and/or site-specific evaluation recommended. Reasonable chance for identifying a minable reserve. Low Development Potential Grade. -Anomalous samples not obtained. No indica- tions that minable grades are present. Reserves. -No established reserves. Geologic conditions are poorly suited for establishing reserves to supply a mine of given size. Study recommendations. -Additional reconnaissance would have little possibility of identifying a minable reserve. Undetermined Development Potential No sample results, or available sample results are in- conclusive. Additional reconnaissance is recommended before development potential is determined. Resource Estimates Order-of-magnitude resource estimates of gravel were made for streams, or portions of streams, having moderate to high potential for placer gold mineral development. Resovu-ce estimates were derived by multiplying the length of the stream section being evaluated by the average width of the flood plain (as identified from available maps and in- formation obtained diu-ing traverses) by the average depth of gravel. Average depths used were based upon field obser- vation as much as possible, but at times were estimated. The results of these estimates are listed in table 1 and in appendix B. CONCLUSIONS Regional studies carried out from 1979 to 1982 in and near the Chugach National Forest evaluated the types of placer deposits present; the origins, characteristics, and distribution of placer gold; and the placer gold mineral development potential of all named drainages and most of their significant tributaries in the CNF. Bulk placer sampling indicated that anomalous placer gold occurs in most drainage basins underlain by Valdez Group rocks. Although the highest gold values and most of the production has been from alluvial and bench deposits, the eluvial, glacial, and marine deposits may locally con- tain significant amounts of gold. Forty -four drainages have moderate to high placer gold mineral development poten- tial. The highest concentrations of placer gold were iden- tified in streams that have previously been mined for placer gold. Results from gold fineness determinations indicated that gold ranged from 455 to over 950 fine in the CNF, with the balance of the samples ranging from 770 to 850 fine. Lode mineral occurrences were discovered by following up metal anomalies identified in placer samples. Placer samples can be used as very large pan concentrates to suc- cessfully detect anomalous base metals or precious metals in stream gravels collected from the numerous short, steep, and poorly graded drainages in which heavy particles have not had the time needed to concentrate because of recent glaciation. 11 REFERENCES 1. Jansons, U., R. B. Hoekzema, J. M. Kurtak, and S. A. Fechner. Mineral Occurrences in the Chugach National Forest, Southcen- tral Alaska. BuMines MLA 5-84, 1984, 43 pp.; 2 map sheets. 2. Nelson, S. W., D. F. Barnes, J. A. Dumoulin, R. J. Goldfarb, R. A. Koski, M. L. Miller, C. G. Mull, W. J. Pickthom, U. Jansons, R. B. Hoekzema, J. M. Kurtak, and S. A. Fechner. Mineral Resource Potential of the Chugach National Forest, South-Central Alaska. U.S. Geol. Surv. Misc. Field Stud. Map MF-1645A, 1984, 24 pp.; 1 sheet. 3. Becker, G. F. Reconnaissance of the Gold Fields of Southern Alaska, With Some Notes on General (Jeology. U.S. Geol. Surv. 18th Annu. Rep., pt. 3a, 1898, pp. 1-86. 4. Mendenhall, W. C. A Reconnaissance From Resurrection Bay to the Tanana River, Alaska, in 1898. U.S. Geol. Surv. 20th Annu. Rep., pt. 7c, 1900, pp. 265-340. 5. Schrader, F. C. A Reconnaissance of Part of Prince William Sound and the Copper River District, Alaska, in 1898. U.S. Geol. Surv. 20th Annu. Rep., pt. 7, 1900, pp. 341-424. 6. Moffit, F. H. Gold Placers of Turnagain Arm, Cook Inlet. U.S. Geol. Surv. Bull. 259, 1905, pp. 90-99. 7. Johnson, B. L. The Gold and Copper Deposits of the Port Valdez District, Alaska. U.S. Geol. Surv. Bull. 622, 1915, pp. 140-188. 8. Martin, G. C, B. L. Johnson, and U. S. Grant. Greology and Mineral Resources of the Kenai Peninsula, Alaska. U.S. Geol. Surv. Bull. 587, 1915, 243 pp. 9. Park, C. F., Jr. The Girdwood District, Alaska. U.S. Geol. Surv. Bull. 849-G, 1933, pp. 381-424. 10. Tuck, R. The Moose Pass-Hope District, Kenai Peninsula, Alaska. U.S. Geol. Surv. Bull. 849-1, 1933, pp. 469-527. 11. Cobb, Edward H. Placer Gold Occurrences in Alaska. U.S. Geol. Svirv. Open File Rep. 81-1326, 1981, 33 pp. 12. Tysdal, R. G. Placer Deposits of Seward and Blying Sound Quadrangles, Alaska. U.S. Geol. Surv. Misc. Field Stud. Map MF-880-B, 1978. 13. Hoekzema, R. B. Placer Sampling and Related Bureau of Mines Activities on the Kenai Peninsula, Alaska. BuMines OFR 138-81, 1981, 28 pp.; 1 map sheet. 14. Fechner, S. A., and M. P. Meyer. Placer Sampling and Related Bureau of Mines Activities in the SOUND Study Area of the Chugach National Forest, Alaska. BuMines MLA 62-82, 1982, 25 pp. 15. Sherman, G. E., and U. Jansons. Feasibility of Gold and Cop- per Mining in the Chugach National Forest, Alaska. BuMines OFR 125-84, 1983, 55 pp. 16. Ransome, A. L., and W. H. Kerns. Names and Definitions of Regions, Districts, and Subdistricts in Alaska. BuMines IC 7679, 1954, 91 pp. 17. Barry, M. J. A History of Mining on the Kenai Peninsula, Alaska. Northwest Publ. Co., 1973, 214 pp. 18. U.S. Bureau of Land Management (Dep. Interior). Mining Claim Report, Window 340, Chugach National Forest. Oct. 19, 1984, 279 pp. 19. Plafker, G., D. L. Jones, and E. A. Pessagno, Jr. A Cretaceous Accretionary Flysch and Melange Terrane Along the Gulf of Alaska Margin. Sec. in U. S. Geological Survey in Alaska: Ac- complishments During 1976, ed. by K. Blean. U.S. Geol. Surv. Circ. 751-B, 1977, pp. B41-B43. 20. Winkler, G. R., and G. Plafker. Geologic Map and Cross Sec- tions of the Cordova and Middleton Island Quadrangles, Southern Alaska. U.S. Geol. Surv. Open File Rep. 81-1164, 1981, 25 pp. 21. Alaska Department of Natural Resources. Anchorage, Bly- ing Sound, Cordova, Seward, and Valdez Quadrangles (Minflle Reference System). 1984, 5 microfiche. 22. Karlstrom, T. N. V. Quaternary Geology of the Kenai Lowland and Glacial History of the Cook Inlet Region, Alaska. U.S. Geol. Surv. Prof. Paper 443, 1964, 69 pp. 12 APPENDIX A.— PLACER DEPOSIT AND SAMPLE DATA Table A-1 gives detailed results of the Bureau's field investigation of CNF placer deposits. Data are reported for samples from numerous locations througout the CNF. The locations of the placer deposits and sample sites listed in table A-1 are shown in figvires A-1 through A- 13 (maps). Table A-1.— Sample results for placers P-1 through P-102 Placer number^ Placer name Sample location Figure Site Sample Sample Gold, type size, yd^ oz/yd^ Gold composition, ppt Gold Silver Base Ratio, - gold to silver Comments, including sample quality^ P-1 Whale NAp .... Copper River P-2 do NAp P-3. P-4. P-5. NAp P-6. NAp. P-7.. Copper River tributary . Shiels Glacier Copper River tributary . McCune Glacier Whiting Falls Tasnuna River Copper River tributary . Cleave Creek P-8.. P-9.. P-10. P-11. P-1 2. P-1 3. P-1 4. P-1 5. P-1 6. P-1 7. P-1 8. P-1 9. P-20. NAp. P-21. P-22. P-23. P-24. P-25. P-26. P-27. P-28. NAp. P-29. P-30. P-31 . P-32. P-33. P-34. P-35. P-36. Marshall Glacier . Deserted Glacier Heiden Creek . . . Bench Creek . . . Wortmann Creek Lowe River Brown Creek Dead Creek . Red Head . . . Port FIdalgo . Black Bear Sulfide Gulch Solomon Gulch Port Fidalgo tributary . Jack Bay tributary . . . Silver Lake Salmon Creek Rainy Day Mineral Creek Gold Creek McAllister Creek . . . . Big Creek Anderson Pass Lake No. 1 Columbia Glacier . . . . Miners River Coghill River Unakwik Inlet . . . Lafayette Glacier Jonah Bay Avery River .... P-37 Siwash Bay P-38. NAp. NAp. Eagiek Bay . . Mount Doran Battles Bay . . A-2 A-2 A-3 A-3 A-3 A-3 A-3 A-3 A-3 A-3 A-3 A-3 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-5 A-7 A-5 A-7 A-7 A-6 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-7 A-8 A-8 A-8 A-8 A-8 A-8 A-8 A-8 A-8 A-8 A-8 A-8 A-8 A-8 A-9 A-9 A-9 1 2 3 4 5 10 10 6 7 8 9 11 12 18 19 20 13 14 15 16 17 21 22 24 25 28 23 35 27 34 29 28 30 31 31 32 33 33 NS 36 37 38 39 40 41 NS NS 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 56 56 57 57 58 59 60 60 Pan . Pan . Pan . Pan . Pan . Pan . Pan . Pan . Sluice .do .do .do .do .do .do .do Pan . Sluice .do .do .do .do .do .do .do .do .do .do .do .do Pan . Sluice Pan . Sluice .do .do .do .do .do NS.. Sluice .do .do .do .do .do NS.. NS.. Sluice .do .do .do .do .do do .do .do .do .do .do .do do .do .do do do do do .do .do Pan . 07 02 02 NS NS NS 006 {') 0.0002 .0001 .0008 .005 .0008 .0005 .002 .0002 .0007 .0009 .0006 .0002 .0003 .0005 .0008 .028 .0001 .0003 .0014 .0004 .0001 .15 .0005 .0005 .002 .0003 .0004 .0002 .0005 .019 .0007 .0002 .0003 .0007 .002 .0002 .0003 .004 NS .0002 .0008 .0004 .0012 .002 .0075 NS NS .0005 .001 .0005 .0003 .0005 .0005 .005 .0004 .0063 .0011 .0021 .001 .0013 .0002 .0083 .0016 .0001 .0036 .0009 .001 .0001 .0009 .018 NS 971 992 994 904 985 705 990 1,000 NS 954 1,000 800 960 898 706 857 958 843 935 967 882 909 925 656 895 958 592 962 855 NS 964 812 989 1,000 948 932 965 855 NS NS 940 976 918 477 835 NS NS 939 886 759 988 849 896 455 NS 799 NS NS NS NS NS 822 NS NS NS NS NS NS NS NS NS 29 8 6 45 2 91 10 NS 43 NS 40 40 74 NS 24 157 33 33 118 91 14 344 54 42 408 38 32 NS 18 31 11 41 68 35 32 NS NS 28 16 57 70 165 NS NS 38 46 87 12 151 8 545 NS 83 NS NS NS NS NS 73 NS NS NS NS NS NS NS NS NS 51 13 204 NS 3 NS 62 220 NS 18 32 61 51 113 NS 18 157 11 113 NS NS 32 8 25 453 NS NS 23 68 154 96 NS 118 NS NS NS NS NS 105 NS NS NS NS NS NS NS NS NS Marine, beach; poor. 33.5 Marine, sand bar; fair. 124 Alluvial fan; poor. 165.6 Gravel bar; good. 20.1 Do. 492.5 Do. 7.7 Do. 99.0 Bedrock; excellent. NAp Alluvial fan; poor. NS Do. 22.2 Gravel bar; poor. NAp Do. NS Alluvial fan; poor. 24 Gravel bar; fair. 22.4 Do. 9.5 Do. NS Bedrock; excellent. 39.9 Alluvial fan; poor. 5.4 Do. 28.3 Gravel bar; fair. 29.3 Do. 7.5 Do. 10 Gravel bar; good. 66.1 Do. 1.9 Do. 16.6 Do. 22.8 Do. 1.4 Gravel bar; poor. 25.3 Do. 26.7 Do NS Do. 53.5 Gravel bar; fair. 26.2 Marine, beach; fair. 89.9 Gravel bar; fair. NAp Do. 23.1 Do. 13.7 Do. 27.6 Do. 26.7 Do. NS NS. NS Alluvial fan; poor. 33.6 Near bedrock; good. 61 Gravel bar; fair. 16.1 Do. 6.8 Alluvial fan; good. 5.1 Do. NS NS. NS NS. 24.7 Bench; poor. 19.3 Alluvial fan; fair. 8.7 Gravel bar; good. 82.3 Alluvial fan; fair. 5.6 Do. 112 Gravel bar; fair. .8 Do. NS Do. 9.6 Bedrock; excellent. NS Gravel bar; fair. NS Do. NS Gravel bar; good. NS Alluvial fan; fair. NS Gravel bar; poor. 11.3 Gravel bar; good. NS Do. NS Gravel bar; fair. NS Do. NS Bedrock; poor. NS Gravel bar; fair. NS Do. NS Bedrock; fair. NS Bedrock; good. See footnotes at end of table. Table A-1.— Sample results for placers P-1 through P-1 02— Continued 13 Placer number^ Placer name Sample location Figure Site Sample Sample type size, yd^ Gold, oz/yd3 Gold composition, ppt Gold Silver Base Ratio, gold to silver Comments, including sample quality^ P-39 . . Pirate Cove A-9 A-9 61 62 Sluice . ..do .. 0.1 0.001 .0009 NS NS NS NS NS NS NS NS Gravel bar; fair. NAp.. . Culross Mine Bedrock; good. P-40. . Billings Creek A-9 63 Dredge Sluice . 51 6.0014 664 157 179 4.2 Do. P-41.. . Carmen River, North Fork . . A-9 64 .0014 NS NS NS NS Gravel bar; good. P-42.. . Twentymile River A-9 65 ..do .. .0001 NS NS NS NS Gravel bar; poor. A-9 66 ..do .. .0035 839 24 137 35 Gravel bar; fair. A-9 66 Pan . . . '02 .0065 805 NS NS NS Bedrock; good. A-9 67 Sluice . .0007 NS NS NS NS Gravel bar; fair. A-9 67 Pan . . . !012 .0037 871 58 71 15 Bedrock; excellent. A-9 68 Sluice . .0005 810 NS NS NS Bedrock; good. NAp. . . Raven Creek A-9 69 ..do .. .0017 NS NS NS NS Gravel bar; fair. P-43. . . Crow Creek A-9 70 Dredge Sluice . 5.67 6.0003 NS NS NS NS Gravel bar; poor. Gravel bar; fair. A-9 71 .0013 NS NS NS NS A-9 72 ..do .. .0042 NS NS NS NS Bench; good. A-9 73 ..do .. .0127 711 154 135 4.6 Bedrock; fair. A-9 73 Pan . . . 5^5 6.012 744 206 50 3.6 Bedrock; good. A-9 73 Sluice . .144 719 209 72 3.4 Bedrock; fair. A-9 73 ..do .. .0021 NS NS NS NS Gravel bar; excellent. A-9 74 ..do .. .039 715 206 79 3.5 Bench; good. A-9 74 ..do .. 1.17 706 248 46 2.8 Bench; bedrock; excellent. P-44. . . Winner Creek A-9 A-9 75 75 ..do .. Pan . . . =4 .0283 5.002 716 709 213 229 72 63 3.4 3.1 Bench; good. Do. P-45. . . California Creek A-9 A-9 76 76 Sluice . . . do . . .0006 .0007 NS NS NS NS NS NS NS NS Bench; fair. Do. P-46. . . Kern Creek A-9, A-1 A-9, A-1 A-9, A-1 77 ..do .. ..do .. Dredge 5l' 6.0004 NS NS NS NS NS NS NS NS NS NS NS NS Gravel bar; poor. Do. P-47. . . Peterson Creek P-48. . . Sawmill Creek Gravel bar; fair. A-9, A-1 77 Pan . . . .05 .0029 NS NS NS NS Bedrock; good. P-49. . . Seattle Creek A-9, A-1 A-9, A-1 78 78 Sluice . ..do .. .001 .0048 NS NS NS NS NS NS NS NS Bench; fair. Do. A-9, A-10 79 Dredge 5l' 6.0001 NS NS NS NS Bedrock; fair. A-9, A-1 80 ..do .. 51 6.0029 NS NS NS NS Do. A-9, A-10 80 ..do .. 51 6.0048 NS NS NS NS Bedrock; good. A-9, A-10 80 Pan . . . .01 .0136 NS NS NS NS Bedrock; excellent. A-9, A-10 81 Dredge 51 6.0014 NS NS NS NS Bedrock; good. A-9, A-10 81 Pan . . . .02 .0301 735 96 169 7.7 Bedrock; excellent. A-9, A-10 82 Dredge 51 6.0009 NS NS NS NS Bedrock; good. P-50 . . . Ingram Creek A-9, A-10 (3) Sluice . .1 C) NS NS NS NS Gravel bar; poor. Bedrock; good. Bedrock; poor. P-51 . . . Wolverine Creek A-9, A-10 A-9, A-10 \ / 83 83 Dredge . .do .. 51 51 6.0036 6.0018 748 NS 68 NS 184 NS 11 NS P-52 . . . Tincan Creek A-9, A-10 A-9, A-10 84 84 ..do .. Sluice . 51 .1 6.0114 .0023 NS NS NS NS NS NS NS NS Bedrock; fair. Bedrock; good. P-53 . . . East Fork and Granite Creeks A-10 A-10 92 93 . .do . . ..do .. .1 .1 .001 .0005 NS NS NS NS NS NS NS NS Gravel bar; fair. Bench; fair. A-10 127 Pan . . . .006 .025 NS NS NS NS Bedrock; good. A-10 127 Sluice . .1 .0267 800 106 94 7.5 Gravel bar; good. A-10 127 ..do .. .1 .032 789 107 104 7.4 Do. A-10 127 Pan . . . .01 .05 788 108 103 7.3 Bedrock; excellent. A-10 127 Sluice . .1 .0035 810 85 105 9.5 Bench; good. A-10 127 . . do . . .1 .0032 797 154 49 5.2 Do. A-10 127 ..do .. .1 .0019 NS NS NS NS Bench; fair. A-10 127 ..do .. .1 .0082 802 130 68 6.2 Bedrock; good. A-10 127 ..do .. 5.4 6.0042 802 118 80 6.8 Bench; poor. P-54 . . . Lyon Creek A-9, A-10 85 Dredge Sluice . 51 6.0132 771 100 29 7.7 Bedrock; excellent. P-55 . . . Taylor Creek A-9, A-10 86 .1 .0011 NS NS NS NS Gravel bar; fair. P-56 . . . Bertha Creek A-9, A-10 87 . .do . . .1 .0129 777 100 123 7.8 Bench; good. A-10 88 ..do .. .1 .0006 NS NS NS NS Gravel bar; fair. A-10 88 Dredge 5.67 6.0142 773 215 12 3.6 Gravel bar; good. P-57 . . . Spokane Creek A-10 89 Sluice . .1 .0001 NS NS NS NS Bench; fair. A-10 90 Dredge 51 6.0022 NS NS NS NS Gravel bar; good. P-58 . . . Pete's Creek A-10 91 Sluice . .1 .0007 NS NS NS NS Bench; fair. P-59 . . . Placer River A-10 A-10 102 102 ..do .. ..do .. .1 .1 .0028 .0001 752 NS 225 NS 23 NS 3.3 NS Gravel bar; good. Gravel bar; fair. A-10 102 Dredge 51 6.0003 NS NS NS NS Do. A-10 102 ..do .. 51 6.0028 NS NS NS NS Bedrock; good. A-10 103 ..do .. 51 6.0015 NS NS NS NS Bedrock; fair. A-10 104 Sluice . .1 .001 NS NS NS NS Gravel bar; fair. A-10 105 Dredge 51 6.0001 NS NS NS NS Gravel bar; poor. A-10 106 Sluice . .1 .0009 NS NS NS NS Gravel bar; fair. P-60.. . Bench and Groundhog Creeks A-10 107 Dredge 51 6.001 NS NS NS NS Bedrock; fair. A-10 108 ..do .. 51 6.0006 NS NS NS NS Gravel bar; poor. A-10 109 . .do .. 51 6.0042 NS NS NS NS Gravel bar; fair. A-10 109 Sluice . .1 .012 NS NS NS NS Bedrock; excellent. A-10 110 Dredge 51 6.0001 NS NS NS NS Bedrock; good. P-61 . . . Lynx Creek A-10 95 Sluice . .1 .0013 NS NS NS NS Alluvial fan; good. A-10 95 Dredge 51 6.0001 NS NS NS NS Gravel bar; poor. A-10 95 ..do .. 51 6.0004 NS NS NS NS Alluvial fan; fair. A-10 96 Sluice . .1 .0036 770 227 3 3.4 Gravel bar; fair. A-10 96 ..do .. .1 .0412 846 131 23 6.5 Bedrock; excellent. A-10 97 ..do . . .1 .0085 NS NS NS NS Bench; good. A-10 97 ..do . . .1 .0203 829 75 96 11.1 Do. A-10 97 ..do .. .1 .0118 NS NS NS NS Do. A-10 97 ..do .. .1 .0163 807 104 89 7.8 Do. A-10 97 ..do .. .1 .0741 NS NS NS NS Do. See footnotes at end of table. 14 Table A-1.— Sample results for placers P-1 through P-1 02— Continued Placer Placer numberi name Lynx Creek Silvertip Creek . . . Center Creek ..do ..do . . . Mills Creek P-64 Colorado Creek P-65 .... Juneau Creek P-66 .... Fresno Creek P-67 .... Canyon Creek P-68 Gulch Creek P-69 .... Sixmile Creek P-69 Falls Creek P-70 .... Bear Creek P-71 .... Resurrection and Palmer Creeks P-72 .... Chickaloon River P-73 Falls Creek P-74 Quartz Creek NAp Slate Creek NAp .... Summit Creek P-75 .... Trail River tributary . NAp .... Moose Creek P-76 Trail River P-77 Cotterell Glacier P-78 .... Taylor Glacier P-79 .... Claremont Glacier . . P-80 .... Kings River P-81 .... Kings River tributary P-82 .... Wolverine Glacier . . P-83 .... Snow River P-84 .... Grant Lake P-85 .... Falls Creek P-86 .... Rarmigan Creek . . . P-87 .... Victor Creek Sample location Sample Sample Gold, Gold composition . PPt Ratio, - gold to silver Comments, including Figure Site type size, yd3 oz/yd3 Gold Silver Base sample quality^ A-10 97 Sluice . 0.1 0.0298 NS NS NS NS Bench, bedrock; good. A-10 97 ..do .. 51.25 6.0087 NS NS NS NS Bench; poor. A-10 97 Dredge 5.5 6.0149 NS NS NS NS Bedrock; good. A-10 98 ..do .. 5.5 5.0011 NS NS NS NS Bench; poor. A-10 94 Sluice . .1 .0019 780 156 64 5 Gravel bar; fair. A-10 99 Dredge 51 5.0001 NS NS NS NS Bedrock; good. A-10 100 ..do .. 51 5.0001 NS NS NS NS Do. A-10 101 ..do .. 51 5.0001 NS NS NS NS Bedrock; poor. A-10 111 ..do .. 51 6.0006 831 43 126 19.3 Bedrock; excellent. A-10 112 . .do .. 51 6.0012 828 72 100 11.5 Bedrock; good. A-10 113 ..do .. 5.75 6.0005 854 19 127 45 Bedrock; poor. A-10 114 ..do .. 51 6.0001 NS NS NS NS Do. A-10 115 ..do .. 51 6.0554 840 69 91 12.2 Bedrock; excellent. A-1 5 115 Sluice . .1 .0001 NS NS NS NS Bench; good. A-10 115 ..do .. .1 .0035 NS NS NS NS Do. A-10 115 ..do .. .1 .0044 NS NS NS NS Do. A-10 116 ..do .. .1 .0869 834 98 68 8.5 Do. A-10 119 ..do .. .1 .0011 NS NS NS NS Gravel bar; fair. A-10 117 ..do .. .1 .0002 NS NS NS NS Do, A-10 118 ..do .. .1 .0022 680 278 42 2.4 ^''ixed gravel and eluvium good. A-10 {') ..do .. .1 W NS NS NS NS Bedrock; good. A-10 121 ..do .. .1 .0006 NS NS NS NS Gravel bar; poor. A-10 120 ..do .. .1 .0054 840 96 64 8.8 Bench, bedrock; fair. A-10 120 Pan . . . .05 .014 855 93 52 9.2 Bench, bedrock; good. A-10 128 Sluice . .1 .0001 NS NS NS NS Bench; fair. A-10 128 ..do .. .1 .0004 NS NS NS NS Do. A-10 122 Dredge 51 6.0034 810 86 104 9.4 Bedrock; poor. A-10 123 ..do .. 51 6.0007 810 53 137 15.3 Bedrock; fair. A-10 124 Pan . . . .025 .0296 761 110 129 6.9 Bedrock; good. Bedrock; fair. A-10 125 Dredge 51 6.0006 786 47 167 16.7 A-10 126 Sluice . .1 .0008 NS NS NS NS Bench; fair. A-10 130 Pan . . . .017 .0214 874 36 90 24.3 Bedrock; good. A-10 131 Sluice . .1 .0017 NS NS NS NS Gravel bar; fair. A-10 132 ..do .. .05 .0028 NS NS NS NS Bench; fair. A-10 132 Dredge 51 6.0182 814 119 67 6.8 Gravel bar; good. A-10 132 . .do .. 51 6.002 784 100 116 7.8 Gravel bar; fair. A-10 133 . .do .. 51 6.0002 NS NS NS NS Bedrock; excellent. A-10 134 Sluice . .1 .0003 NS NS NS NS Gravel bar; fair. A-10 135 ..do .. .1 .0073 745 62 193 12 Bedrock; good. A-10 136 ..do .. .1 .0021 697 267 36 2.6 Mixed gravel bar and eluvium; poor. A-10 137 Washing plant . 1,000 NS 837 117 46 7.2 Gold donated by mine ovifner. A-10 138 Sluice . .1 .0006 NS NS NS NS Gravel bar; fair. A-10 139 Pan . . . .03 .0042 808 23 169 35.1 Gravel bar; good. A-10 140 Sluice . .1 .0024 747 144 109 5.2 Bedrock; good. A-10 140 ..do .. .1 .034 795 122 83 6.5 Bench, bedrock; good. A-10 140 Pan . . . .0003 4.5 817 97 86 8.4 Tailing from spiral concentrator. A-10 141 Pan . . . .006 .0384 NS NS NS NS Bedrock; excellent. A-10 141 Sluice . .1 .0024 NS NS NS NS Gravel bar; fair. A-10 142 ..do .. .1 .0048 NS NS NS NS Eluvial gravel; good. A-10 143 ..do . . .1 .0001 ' NS NS NS NS Gravel bar; fair. A-10 144 Dredge 51 6.0006 NS NS NS NS Do. A-10 145 ..do .. 51 6.0001 NS NS NS NS Bedrock; excellent. A-10 146 ..do . . 51 6.0005 NS NS NS NS Bedrock; fair. A-10 146 Sluice . .05 .0003 NS NS NS NS Bench, bedrock; fair. A-10 147 ..do . . .1 .0015 NS NS NS NS Gravel bar; good. A-10 148 Dredge 51 6.0012 NS NS NS NS Bedrock; good. A-10 148 ..do . . 51 6.0007 NS NS NS NS Bedrock; fair. A-11 149 Sluice . .1 .0005 NS NS NS NS Gravel bar; fair. A-11 150 ..do .. .1 .0044 677 238 85 2.8 Do. A-11 151 ..do .. .1 .0013 NS NS NS NS Do. A-11 152 ..do . . .1 .0083 812 100 88 8.1 Bedrock; good. A-11 152 ..do . . .1 .0014 NS NS NS NS Gravel bar; fair. A-11 152 Dredge 51 6.0017 827 104 69 8 Bedrock; good. A-11 153 Sluice . .1 .0003 NS NS NS NS Gravel bar; fair. A-11 154 ..do . . .1 .0035 742 94 164 7.9 Gravel bar; good. A-11 155 ..do .. .1 .0002 NS NS NS NS Do. A-1 2 156 ..do .. .1 .0006 NS NS NS NS Do. A-1 2 157 Pan . . . .006 .0464 NS NS NS NS Bedrock; excellent. A-1 2 157 Dredge 5.67 6.0001 NS NS NS NS Gravel bar; fair. A-1 2 158 Sluice . .1 .0011 NS NS NS NS Do. A-1 2 159 Dredge 51 6.0002 NS NS NS NS Bedrock; good. A-1 2 160 . . do . . 51 6.0006 779 39 182 20 Do. A-1 2 161 Sluice . .1 .0022 NS NS NS NS Gravel bar; fair. A-1 2 162 . . do . . .1 .0027 NS NS NS NS Eluvial gravel; good. A-1 2 163 Dredge 51 6.0002 NS NS NS NS Bedrock; poor. A-1 2 164 Sluice . .1 .0009 NS NS NS NS Eluvial gravel: fair. A-12 165 . . do . . .1 .0077 NS NS NS NS Active mine cut; good. A-1 2 166 ..do .. .1 .0003 NS NS NS NS Bench; good. A-12 167 ..do .. .1 .0002 NS NS NS NS Gravel bar; fair. A-12 167 ..do .. .1 .0007 NS NS NS NS Do. A-12 168 ..do . . .1 .0043 745 111 144 6.7 Bedrock; good. P-61 P-62. NAp. P-63. See fcK)tnotes at end of table. Table A-1.— Sample results for placers P-1 through P-1 02— Continued 15 Placer number' Placer name Sample location Figure Site Sample Sample type size, yd' Gold, Gold composition, ppt oz/yd3 Gold Silver Base Porcupine Creek A-1 2 A-1 2 Ship Creek A-12 A-1 2 A-12 A-12 A-12 Crescent Creek A-12 A-12 A-12 A-12 Hargood Creek A-12 A-12 A-12 Dry Creek A-12 Kenai River A-12 A-12 A-12 A-12 A-12 Cooper Creek A-12 A-12 A-12 Ratio, gold to silver Comments, including sample quality^ P-88. P-89. P-90. P-91. P-92. P-93. P-94. P-95. P-96. P-97. P-98. P-99 . . P-1 00. P-1 01 . P-1 02. Stetson Creek Cooper Lake tributary Boulder Creek Martin Creek Redman Creek . Paradise Creek Lost Creek . . . . Goat Harbor . . . A-12 A-12 A-12 A-12 A-12 A-12 A-12 A-12 A-12 A-12 A-12 A-12 A-12 A-12 A-1 3 169 Sluice 169 Pan . . 170 Dredge 171 ..do 172 ..do 172 Sluice 173 ..do 175 175 175 174 174 176 177 180 181 191 191 192 194 do .do do 175 Pan . 174 Sluice . do . do . do ..do 177 Dredge 178 Sluice . do . ..do . 179 Sluice 182 ..do . 183 Sluice 184 Dredge 185 Sluice 186 . .do . 187 ..do . 188 ..do . 189 Dredge 190 ..do . 191 . .do . Sluice Pan . . 193 Sluice ..do . ..do . 195 Pan . . (3) Sluice 0.1 0.0008 NS NS NS NS Gravel bar; fair. .02 .0022 NS NS NS NS Bedrock; fair. =1 6.0002 NS NS NS NS Bedrock; fair. 51 6.0001 NS NS NS NS Gravel bar; poor. 51 6.0081 759 76 165 10 Bedrock; good. .05 .0304 824 57 119 14.5 Bedrock; excellent. .1 .0001 NS NS NS NS Gravel bar; fair. .1 .01 770 82 148 9.4 Bench; good. .05 .031 770 124 106 6.2 Do. .1 .015 818 64 118 12.8 Gravel bar; good. .04 .0135 773 111 116 7 Bedrock; excellent. .1 .0289 804 186 10 4.3 Alluvial fan; good. .1 .0036 731 215 54 ' 3.4 Do. .1 .0315 764 211 25 3.6 Do. .1 .0005 NS NS NS NS Gravel bar; fair. .1 .0027 826 111 63 7.4 Gravel bar; good. 5.5 6.003 NS NS NS NS Gravel bar; fair. .1 .0135 814 106 80 7.7 Gravel bar; good. .1 .0449 860 80 60 10.8 Gravel bar; excellent. .1 .0001 NS NS NS NS Gravel bar; good. .1 .0018 820 136 44 6 Gravel bar; fair. .2 .019 NS NS NS NS Behch; good. .1 .0046 NS NS NS NS Mixed gravel bar and eluvium; fair. 5.75 6.0001 770 42 288 18.3 Bedrock; poor. .1 .01 572 156 272 3.7 Bench; good. .1 .0043 835 53 112 15.8 Bedrock; good. .1 .0008 NS NS NS NS Gravel bar; fair. .1 .0003 NS NS NS NS Bench; fair. 51 6.0001 808 NS NS NS Bedrock; fair. 51 6.0006 806 36 158 22.4 Bedrock; fair. 51 6.0278 819 61 120 13.4 Do. .1 .0106 807 174 19 4.6 Gravel bar; fair. .02 .1537 829 67 104 12.4 Bedrock; excellent. .1 .0004 NS NS NS NS Gravel bar; fair. .1 .0003 NS NS NS NS Do. .1 .0001 NS NS NS NS Do. .02 .0003 NS NS NS NS Bedrock; good. .1 C) NS NS NS NS Gravel bar. NS Not sampled or not determined. NAp Not applicable. ■"From maps in appendix A. Samples with placer numbers are described in appendix B; those without placer numbers are not. ^Excellent: Bedrock reached, little water in hole (unless collected by suction dredge). Good location for gold to accumulate. Sample value likely greater than average value of gravels in immediate area. Good: Bedrock reached, may have water in hole. Fair to good area for gold to accumulate. Sample value likely to be representative of that of gravel in im- mediate area. Fair: Bedrock not reached and/or poor location for gold to accumulate. Sample value may be less than that of gravel in immediate area. Poor: Bedrock not reached and water in hole. Poor location for gold to accumulate. Sample value likely to be less than that of gravel in immediate area. 'Sample collected, but gold content too low for analysis. (Location not specifically identified.) *Gold content too low for analysis. 5Hour (amount of sample collected In given time). 60unce per hour. 16 Legend for Figures A-1 Through A-13 P-5/* ^ A-1 and appendix B) . Location of placer deposit and deposit number (numbers used in tables 1 and O Placer sample site where trace amounts or no visible gold was recovered 9 Placer sample site where quantity of gold was large enough to be weighed. (Site numbers correspond to those used in "Sample location" column in ap- pendix B.) Chugach National Forest boundary 17 CO I < O) 3 O CM < (0 0) 3 O) a. ra E X 0) ■o c Ul (0 00 ^,W».) 1 I /A.>,"i «^ iC 5^ "T 4'"? "/«;/-/!;) tA^J^^ .4av^ •!>'« 4i.A(^ 0%// > ■■■/ '> • -XY '^ •=• "•'^■iffi-? ,;.Vs-->-' ili---7 -"^3--. -'J "^1 •^1 \ --/ f it -'■■ft*. '^^ /■ J:'^' '"■■■> 'W-^-:-:" A^ 4. ',^'5^ // 19 U I '1 § ~ >

. v^^-'" ,jTI4S .^^^,v <■■ <> K_ cr * J^^^^^jfr^'^j"/ 5S r -^— >'- ^4j_^ .__^wv;j^^--, -|;^;^^ Bom (Ktapted from U S G S I 2 50 000 Cordovo ond Voldez quadrangles IT''*"''!? ^ y ? ,'^ 60030' r4 ^ ]■ §fe& vr^_ 1 Vv '4^ > "^ pf-- ^ 1 ^ -^- , / . ..„ Wao> 1 '''s^i. ~x i^^ m 1 r-^ '-^.r-^^^-',..^ ■-V J.-? . U l"~ ■'«' ^ ?>$.v <., \ "■""'■.^ A D E I T A t^#/-e J ^MC R 1 V V"TI7S '-;;. .J.%, ^ x/:- Bose Qdoplcd from U.S.G.S. I 260,000 Co, fdovo quodrangl« ^ Ties Scale, miles Contour Interval 200 ft FIGURE A-4. Scott Glacier area. 21 CO a. ^ at JO / r 0-/ ro I i o o o ^ O' ) ® Q O (0 o XL H-t"' to CD Q. fe^ ■"i- -.^-A -jsin -,< '""-;; Ji3«vs.'s«-^Ai)8i^*4i«(jl (O -t o o- E® c o o UJ cc g u. R7W fiif R6W IfiK R5W O 146" o R4W R3W TI2S ^i^ <,)! : ■-60°45' o,^ .16 ►A' / ,«*^ Gi^vins ^i- A ■6^ ^r 'i^ .>«^ O R C A /"^^-^^v^. fl A ¥'■'■' -::_-j?iv:i ^-- ..*'. ^ . ,*r^&: s5--vii-. ■■■■•I Ci ^i^~^%^ '-■ .^^„:..- -. \ ■\ ^ Art 'MP--' ■■ _~'- y- /.■■\t v-'^feaC-^-iJ-Si'^'j,. .'■ '„ '' ":"X ,',. V" •' ^^ 1 riivrk^. ft WhltshoaJx''--'^-"'^ 6S ■•.■^,. ^ V^;TI7S Boi. odopt.d from U.S.G.S. I 250,000 Cordova quodrongU " Scale, miles Contour Interval 200 ft FIGURE A-6. Orca Bay area. 23 = CO CO 00 a: l\i: /# CO o 0> o >- 5 p - '-^^ .. 1 - iJ d/J'^^^V-v ■ . .■/-^ A 'V •■ ■ ■■/ /i/'^-.,.'--' '/; .-../■••i ■ lo-'"'L-' / : ■■.\' -" ;./o,Hr •:"■■:■ ' ' 70;- /^-^-v^y.- (0 0} CM ^ UJ ■■^<-<^ ■^.. ^'^^/0./:7>oV'' / 24 CO 1- o ''^''^ ? ' (r -i -v^l /4 CO o j...^_^ — r-'a:!?^ '^:^^ .^ ■ X - ^'?.. ? V4^3^. ^ 1 \ UJ O O o 01 Vol J-1 } ^± z z to C\I O =.' _ ^"'y I - O a. ^-^ -^ --^ D o o ro CL " '^} V / 6 -> t"" s<7 ^ ^^^C-^/^ If) ■ to 'J- d 1^ tn: O ^ ., to W ^_ Cl/" •4 <0£ « O ^X o o ^ to ' «| J v.- •• 1 * A, ;^ ■C^KKY ARM ^ ? -% o o meg 9 ^_ — o E£ • 2 o c O-l 1 CO c 3 ed I < UJ flC 3 O iZ 25 00 z *- o o ' - ■> c a 'o' o o-i 0) k n w *- a> o 5 o t CM o »— . a. 0) o ■a o o 0> ^ 3 o — ■o o <- Ui 3 (3 o c o> o o < Ui CE 3 o 26 « e u c c n U « £ o c o o v 3 w o OHf ^.UaVMIXOHfUJV* - 27 R3E I48»30' ^ ^R6E O- v^i -'^^ o o O *T6N O > r-s?«?^f5« u-r' \ c i ^5f Of I ^54 T5N i*60°30 Base odopltd from U.S.G S. h 250,000 Seword quodrongle L '&7S3'« T4N <;T3N Scole, miles Contour Interval 200ft FIGURE A-11. Kings Bay area. 28 «. " « a a c e lU o C '^.^k.^=»«*^^i^ »i^'-^' !v^ '^^''^fc;^ S ^1 1 T3S V \. ,.■=00' Base odopted from U.S. 62. h 250,000 Sevord and BIying Sound quadrangl* 5 L I \. \ X Scole, miles Contour interval 200ft FIGURE A-13. Puget Bay area. 30 APPENDIX B.— PLACER DEPOSIT DESCRIPTIONS Placer number! Deposit location^ Mineral development potential ToduK" Summary of mineralization No data; no reported production. Beach sands. None Quaternary alluvial sands and gravels in Copper River. Gold concentrations in gravel between Tasnuna River and Miles Lake. . . do Alluvial and colluvial gravels in drainage that drains metamorphosed sedimentary rocks. . . do Do. . .do Alluvial gravels in a drainage that drains metamorphosed sedimentary and volcanic rocks. Shear zone containing quartz, galena, and pyrrhotite crops out in the drainage. None Quaternary alluvial gravel derived from metamor- phosed sedimentary and volcanic rocks. . .do Do. . . do Quaternary alluvial gravels derived from metamor- phosed sedimentary and volcanic rocks. A 0.025-in-diam flake vi/as recovered from the gravels. 4-ft-wide malachite-stained greenstone crops out on south side of creek. . . do Quaternary alluvial gravels derived from metamor- phosed sedimentary rocks. . .do , Do. . .do Do. Placer gold operation. No reported production. Quaternary alluvial gravels. None Quaternary alluvial gravels derived from metamor- phosed sedimentary rocks. Mineralization con- sists of fine-grain gold and reported scheellte near mouth of river. . . do Quaternary alluvial gravels derived from metamor- phosed sedimentary and volcanic rocks. . .do Quaternary alluvial gravels contain slate, graywacke, phyllite, greenstone, and andalusite schist cobbles and boulders. 1 pet garnet in concentrate. No data; no reported production. 1-ft-thick beach sand over sandy pebbly layer. Pebbles are felsic intrusives, greenstones, graywackes, and slates. 10 pet garnet in concentrate. None Quaternary alluvial gravels consist of slate, graywacke, greenstone, and quartz cobbles and boulders. Placer gold operation. No reported production. Quaternary alluvial gravels derived from metamor- phosed sedimentary rocks. . . do Quaternary alluvial gravels derived from metamor- phosed sedimentary and volcanic rocks. Other minerals present in heavy fraction include garnet, pyrite, chalcopyrite, magnetite, zircon, and scheelite. . . do Quaternary alluvial gravels derived from metamor- phosed sedimentary and volcanic rocks. None Do. . .do Do. . . do Do. P-1 Cordova: A-2; sec. 6, T. 208, R. 5E (CRM). P-2 Valdez: A-3; Cor- dova: C-2, D-2 (CRM). P-3 Cordova: D-2; sec. 27, T. IIS, R. 4E (CRM). P-4 Cordova: D-2; sec. 22, T. IIS, R. 4E (CRM). P-5 Cordova: D-3; sec. 24, T. 11S, R. 3E (CRM). P-6 Valdez: A-3, A-4; T. 10S, R. 3E (CRM). P-7 Valdez: A-3; T. 9S, R. 2E (CRM). P-8 Valdez: A-4; T. 9S, R. 2W (CRM). Low Moderate . Low Low Low Moderate . .do High. P-9 . . . . . . Valdez; A-5; T. 9S, R. 2W (CRM). Low P-10 ... .. . .do Low P-11 . . . . . Valdez: A-5; T. 9S, R. 3W (CRM). Moderate . . . . P-12 . . . .. . .do Low P-13 . . . . . Valdez: A-5, A-6; T. 9S, R. 5W (CRM). Low P-14 . . . . . Valdez: A-5; T. 20S, R. 4W (CRM). Moderate .... P-15 ... . . Cordova: D-6; T. 11S, R. 4W (CRM). Low P-16 ... . . Cordova: C-7; sec. 4, T. 14S, R. 7W (CRM). Low P-17 . . . . . Cordova: D-6; T. IIS, R. 5W (CRM). Moderate .... P-18 .. . . . Valdez: A-6; sec. 21, T. 9S, R. 4W (CRM). Unknown . . . . P-19 . . . . . Valdez: A-6; T, 9S, -'. 5W (CRM). Low P-20 . . . . . Valdez: A-7; T. 9S, R, 6W (CRM). Low P-21 . . . . . Cordova: D-7; sec. 25, T. 10S, R. 7W (CRM). Low P-22 . . , . . Cordova: D-7; sec. 32, T. 10S, R. 7W (CRM). Moderate . . . . P-23 . . . . . Valdez: A-7; T. 9S, R. 7W (CRM). ..do P-24 . . , . . Valdez: A-7; sec. 18, T. 9S, R. 6W (CRM). Low P-25 . . . . Valdez: A-7; T. 8S, R. 6W (CRM). Moderate . . . . P-26 . . . Valdez: A-7; T. 8S, R. 7W (CRM). Low Placer gold operation. No reported production. ..do ..do Quaternary alluvial and beach gravels. Do. Quaternary alluvial gravels contain 5 pet clay, and slate, graywacke, and quartz pebbles and cob- bles. Gravel is 9 to 50 ft thick. See footnotes at end of table. 31 Placer number^ Deposit location^ Mineral development potential Worl1 million yd^ In addition, three basic grades are described: LOW-<0.005 oz/yd^" Au. MEDIUM-0.005-0.02 oz/yd' Au. HIGH->0.02 oz/yd^ Au. ALLUVIAL PLACERS Alluvial placers are gravel deposits resulting from the depositional and sorting processes of existing streams. They include gravel bars, channel deposits, floodplain deposits, and alluvial fans. Gravel Bars Gravel bars contain loose, sandy, moderately sorted gravel; pay streaks are often discontinuous and are confined to near-surface accumulations of flood gold.^ 'Flood gold consists of small «0.04 in diam), very thin flakes that are readily transported by streams during flood condi- tions. The gold is commonly deposited near the surface and at the head of gravel bars. Values commonly do not persist at depth. Size: SMALL. Typical bars may contain up to 10,000 yd^. Grade: LOW to HIGH. Up to 0.14 oz/yd* Au has been recovered from samples. Production grades of 0.01 to 0.02 oz/yd' Au have been reported. Gold characteristics: Gold is typically fine grained «0.04 in diam) and flaky; it readily floats on water. Production history: Gravel bars have been mined with small, mechanized equipment on Mills (P-63), Canyon (P-67), Sixmile (P-69), Resurrection (P-71), and Crescent (P-90) Creeks. Future potential: Deposits have been identified on most streams having previous production history and also on the Trail (P-76), Kings (P-80), Snow (P-83), and Kenai (P-93) Rivers. Large suction dredges (>8 in) might have success mining these deposits. Highly efficient gold recovery techniques will be needed to adequately recover the gold, because of its size and shape. Channel Deposits Channel deposits are stratified, loose, sandy, actively migrating gravels resting on moderately consolidated clay-bearing gravels with angular bedrock fragments and boulders on bedrock. Size: VERY SMALL. Deposits are small and discontinous. High-grade pockets typically con- tain <100 yd'. Grade: HIGH. For suction dredges, production grades of 0.05 to 0.5 oz/yd' Au are not unusual. Gold characteristics: Gold is fine-grained near the surface with increasing size and weight on bedrock. Coarse flakes and nuggets up to 1/2 oz or more may be recovered within the clayey consolidated layer and from bedrock fractures. Production history: Suction dredges have been successfully used to mine these deposits on Crow (P-43), Bertha (P-56), Mills (P-63), Canyon (P-67), Gulch (P-68), Sixmile (P-69), Resurrection (P-71), and Cooper (P-94) Creeks, and several other drainages on the Kenai Peninsula. Recoveries of 1/4 oz to several ounces per day have been reported depending upon dredge size, water condi- tions, and grade. Future potential: Suction dredging will continue on previously mined drainages. Additional areas could include the Avery (P-36), Placer (P-59), Trail (P-76), and Kings (P-80) Rivers and Seattle (P-49), Falls (P-85), Ship (P-89), Crescent (P-90), and Martin (P-98) Creeks. 41 Flood Plain Deposits Flood plain deposits tend to consist of poorly sorted, moderately consolidated, stratified gravels containing a significant clay-silt matrix resting directly on bedrock or, as at portions of Resur- rection Creek (P-71), upon clay hardpan. Size: SMALL to LARGE (depending upon drainage). More than 1 million yd^ of gravel occurs along the Trail (P-76), Kings (P-80), Snow (P-83), and Kenai (P-93) Rivers and on Crow (P-43), Sixmile (P-69), and Resurrection (P-71) Creeks. Grade: MEDIUM. These deposits have variable grades; the highest grades occur in previous channels. Production grades of 0.008 to 0.02 oz/yd^ Au have been reported. Gold characteristics: Grold is mostly fine-grained and flaky with some coarsening to be ex- pected on bedrock. Nuggets up to 1/2 oz or more have been recovered from a few streams. Production history: A significant portion (approximately 50 pet) of the total placer gold pro- duction from the Kenai Peninsula has come from this type of deposit. Mines have been located on Crow (P-43), Mills (P-63), Canyon (P-67), Sixmile (P-69), Bear (P-70), Resurrection (P-71), Cres- cent (P-90), and other creeks. Historically these deposits were first mined by pick and shovel, followed by hydraulic techniques and most recently by mechanized methods. Future potential: Continued placer mining can be anticipated on the historically mined drainages. New and/or additional operations mining flood plain deposits could be developed upon the Avery (P-36), Placer (P-59), Trail (P-76), and Kings (P-80) Rivers and on Billings (P-40) and Seattle (P-49) Creeks should gold prices rise significantly. Mining will require using mechanized equipment with refined recovery techniques capable of efficiently recovering <60-mesh gold. Alluvial Fan Deposits Alluvial fans develop where relatively steeply sloping streams suddenly develop more gradual gradients. Such deposits on the Kenai Peninsula consist of fanlike patterns of poorly sorted, un- consolidated gravels with a moderate to high clay content. Size: SMALL to MEDIUM. Typical alluvial fans consist of 250,000 yd^ or less. Larger fans containing in excess of 1 million yd^ occur at the mouth of Lynx (P-61), Silvertip (P-62), and Bear (P-70) Creeks. Grade: LOW to MEDIUM. Production grades of 0.01 to 0.02 oz/yd* Au have been reported from Hargood Creek (P-91), but Bureau sampling indicates grades are generally <0.005 oz/yd^ Au at most deposits. Gold characteristics: (jold is generally fine-grained and flaky with particles >0.08 in rare. The gold occurs in distributary channels and is commonly present from surface to bedrock. Production history: Limited amounts of gold have been produced from this type of deposit. Production has occurred from alluvial fans at Bertha Creek (P-56), and more recently from Hargood Creek (P-91). Portions of the bench deposits on Lower Crow Creek (P-43) appear to be alluvial fan deposits but have been classified as bench deposits. Future potential: Alluvial fans previously mined may be mined in the future. Fans needing further evaluation occur on Lynx (P-61), Silvertip (P-62), Bear (P-70), and Ship (P-89) Creeks and possibly several other drainages on the Kenai Peninsula. The tendency for gold to occur in chan- nels within the fan deposits must be considered for proper evaluation. BENCH DEPOSITS Bench deposits are deposited by streams at higher elevations within present valleys prior to formation of the more deeply eroded active stream channels of today. Some of these deposits, which include abandoned channels, were apparently deposited during interglacial periods prior to the most recent advance. Gravels tend to be poorly to moderately well stratified, poorly sorted, and moderately well consolidated. Benches occur at levels of a few feet to more than 150 ft above current streams. Bench gravels are often covered by avalanche debris. Size: SMALL to LARGE. Benches containing in excess of 1 million yd^ have been identified on several drainages including Canyon (P-67), Sixmile (P-69), and Resurrection (P-71) Creeks. Significant 0200,000 yd^) volumes of bench gravel also occur on Crow (P-43), Winner (P-44,) Seattle (P-49), Lynx (P-61), Mills (P-63), Quartz (P-74), Hargood (P-91), and Stetson (P-95) Creeks. Grade: LOW to HIGH. Bench gravels tend to be lower in grade than many of the adjacent alluvial gravels, but have been conducive to mining using relatively high-volume low-cost hydraulic methods. Production grades from 0.005 to 0.04 oz/yd^ Au have been reported. Lower grades are likely for the bulk of the deposits identified. Samples collected from East Fork (P-53) and Canyon (P-67) Creek benches contain from 0.004 to 0.016 oz/yd^ Au. Gold characteristics: Gold is generally less than 0.1-in. in diameter and flaky, with local ex- ceptions, such as on Crow (P-43) Creek where nuggets up to 1 oz have been recovered. Production history: Bench deposits have supplied a significant portion (up to 40 pet) of the total placer gold production from the Kenai Peninsula. The majority came fi-om 2 drainages: Crow 42 (P-43) Creek and the junction area of Mills (P-63) and Canyon (P-67) Creeks. Additional produc- tion has come from East Fork (P-53), Lynx (P-61), Gulch (P-68), Sixmile (P-69), Resurrection (P-71), Quartz (P-74), Cooper (P-94), and Stetson (P-95) Creeks. Future potential: Future mining of bench deposits may occur on historically mined drainages. Hydraulic mining will likely be replaced by mechanized methods for larger deposits. Small high- grade deposits may be mined using pumps to supply water. ELUVIAL DEPOSITS Eluvial deposits are produced by the concentration of heavy minerals due to the winnowing action of gravity and downhill creep. They occur as irregular sheets of angular rock fragments and soil-mantling hillside slopes below gold-bearing quartz veins. Size: No data. Grade: LOW. Economic concentrations have not yet been located in the CNF. Gold characteristics: Gold is reported to be rough, nuggety, and fine-grained. Coarse gold (X>.1 in) has not been identified. Production history: None. The Grant Lake Development Co. sampled for eluvial placer potential below the Case Mine near Grant Lake, but could not identify economic concentrations. Future potential: Exploration activity possibly followed by mining, if warranted, might be anticipated on slopes below exposed gold-besiring quartz veins such as those occurring on the north side of Falls (P-85) Creek, on the steep slopes between Summit and Slate Creeks, the Crow Pass area near Girdwood, and along Palmer (P-71) Creek near Hope. GLACIAL DEPOSITS Glacial deposits consist mostly of till or very poorly washed, largely unstratified gravels con- taining abundant clay and angular rock fragments. These deposits often form steep cut banks up to 200 ft high where they have been eroded by subsequent stream action, as at the mouths of Juneau (P-65) and Palmer (P-71) Creeks. Size: SMALL to LARGE. May exceed 1 million yd*, however, volume estimates were not made. Grade: LOW. Economic concentrations have not been identified. However, these deposits may be a source of gold that can be reworked and concentrated into alluvial placers. Gold characteristics: Gold is disseminated throughout these deposits and is best described as being of the flour variety (i.e., very fine-grained and thin). Production history: Minor production may have come from what are believed to be mostly till deposits near the mouth of Juneau (P-65) Creek. Alluvial placers produced below Eireas where streams have eroded large recessional moraines, such as at the junctions of Palmer and Resur- rection (P-71) and Mills and Canyon (P-67) Creeks, have been previously discussed. Future potential: Some potential for exploration or mining of glacial placers may exist along portions of Crow (P-43), lower Juneau (P-65), and Palmer (P-71) Creeks. MARINE DEPOSITS Marine deposits are loose, well-sorted, stratified sands and gravels. Size: LARGE. May exceed several million cubic yards. Grade: LOW. Samples collected contained from a trace to 0.002 oz/yd* Au. Gold characteristics: Gold is very fine-grained and flaky. Production history: None. Future potential: Large, very low-grade deposits are present at the mouth of the Copper River and on some beaches along the northern Prince William Sound coast. These deposits currently cannot be mined profitably. 55S7 37-1 .<^^°^ <, 'o-.;- 0^^ V^^> %-.^%o^'' V^^^^\'^ ^^^9^' -^^^^^ »* ^0 '. -n^.o^ f-'^B". '^ov^ :m^^^ ^^^c %'rff^'\^^- V ^v % vT Pv. a5°X. O^ 'o . » «5^^ 'JU t*^ r.s* <&^ ^oV <0^ ^l*f' ^> ^""^ ^^-^^^ ,^>- V"^''/ ^o/*^'^^/ V^^^o' "^^ - .•1' . -x^ - /~'a^-'°- /--'^X ^°-:^^-> ./.-^i.^ /.c^-"""- / ii f • aV<:> - / •* ■% ,^° -i^-^ y.-^i>^ '"V^-""- /W---. '**/ ^ ■^(y ■^.-f •• "W* A'-. \/ :'Mk- %,*" -'^SK'. **, JAN.-FEB. ^a xO r\^ . » » o '^''*" -ov-^^