STATE OF ILLINOIS DWIGHT H. GREEN, Govtmor DEPARTMENT OF REGISTRATION AND EDUCATION FRANK G. THOMPSON, Dincxor DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON. Chief URBANA REPORT OF INVESTIGATIONS — NO. 79 FELDSPAR IN ILLINOIS SANDS A Study of Resources H. B. WILLMAN PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS 1942 ORGANIZATION STATE OF ILLINOIS HON. DWIGHT H. GREEN, Governor DEPARTMENT OF REGISTRATION AND EDUCATION HON. FR.\NK G. THOMPSON, Director BOARD OF NATL RAL RESOURCES AND CONSERX ATION HON. FRANK G. THOMPSON, Chairman EDSON S. BASTIN, Ph.D., D.Sc, Geology ROGER ADAMS, Ph.D., D.Sc, Chemistry LOUIS R. HOWSON, C.E., Engineering WILLIAM TRELEASE, D.Sc, LL.D., Biology EZRA JACOB KRAUS, Ph.D., D.Sc, F:>restry ARTHUR CUTTS WILLARD, D.Engr., LL.D.. PreriJent of the University of Illinois GEOLOGICAL SURVEY DIMSION M. M. LEIGHTON, Chief (22453) .-1 SCIENTIFIC AXD TFXHXICAL STAFF OF THE STATE GEOLOGICAL SURVEY DIVISION 100 Natural Resources Building, Urbana M. M. LEIGHTON, Ph.D., Chief Enid Towxley, M.S.. Assistant to the Chief Jane Titcomb, M.A., Geological Assistant GEOLOGICAL RESOURCES GEOCHEMISTRY Coal G. H. Cady. Ph D.. Senior Geologist and Head L. C. McCabe. Ph.D.. Geologist (on leave) R. J. Helfinstine, M.S.. Assoc. Meek. Eng. James M. Schopf. Ph.D., Asst. Geologist J. Norman Payne. Ph D., Asst. Geologist Charles C. Boley, M.S., Asst. Mining Eng. Bryan Parks, M.S., Asst. Geologist Industrial Minerals J. E. L.AMAR. B.S., Geologist and Head H. B. WiLLMAN, Ph.D., Assoc. Geologist Douglas F. Stevens, M.E., Research Associate Robert M. Grogan. Ph.D., Asst. Geologist Robert R, Reynolds, B.S., Research Assistant Oil and Gas A. H. Bell, Ph.D., Geologist and Head G. V. CoHEE, Ph.D., Asst. Geologist Frederick Squires, B.S., Assoc. Petr. Eng. Charles \V. Carter, Ph.D., Asst. Geologist William H. Easton, Ph.D., Asst. Geologist Paul G. Luckhardt, M.S., Research Assistant Wayne F. Meents, Research Assistant A real and Engineering Geology George E. Ekblaw, Ph.D., Geologist and Head Richard F. Fisher, M.S.. Asst. Geologist Subsurface Geology L. E. Workman, M.S., Geologist and Head Tracy Gillette, Ph.D., Asst. Geologist Arnold C. Mason, B.S., Asst. Geologist Kenneth O. Emery, Ph.D., Asst. Geologist Merlyn B. Buhle. M.S., Asst. Geologist Frank E. Tippie, B.S.. Asst. Geologist Ruth E. Roth, B.S., Research Assistant Stratigraphy and Paleontology J. Marvin Weller, Ph.D., Geologist and Head Chalmer L. Cooper, AI.S., Assoc. Geologist Petrography Ralph E. Grim, Ph.D., Petrographer Richards A. Rowland, Ph.D., Asst. Petrographer Physics R. J. PiERSoL, Ph.D., Physicist B. J. Greenwood, B.S.. Mech. Engineer Donald O. Holland, M.S.. .4sst. Physicist (on leave) Frank H. Reed. Ph.D., Chief Chemist H. W. Jack MAN, M.S.E., Chem. Eng. Roberta M. Langenstein, B.S., Chemical Assistant Melville A. Rogers, B.S.. Research Assistant Coal G. R. Yoke, Ph.D., Assoc. Chemist Myron H. Wilt, B.S., Research Assistant Industrial Minerals J. S. Machin. Ph.D., Chemist and Head Delbert L. Hanna, A.m., Research Assistant Fluorspar G. C. Finger, Ph.D., Assoc. Chemist Everett W. Maynert, B.S., Research Assistant X-ray and Spectrography W. F. Bradley, Ph.D., Assoc. Chemist Analytical O. W\ Rees, Ph.D., Chemist and Head L. D. McVicker, B.S., Asst. Chemist P. W. Henline. M.S., Asst. Chemical Engineer William F. Wagner, M.S.. Asst. Chemist K. F. Bursack, B.A., Research Assistant Marion Lund Dick man, B.S., Research Assistant MIXERAL ECONOMICS W. H. VosKuiL, Ph.D., Mineral Economist Grace N. Oliver, A.B., Assistant in Mineral Economics EDUCATIONAL EXTENSION Don L. Carroll, B.S., Assoc. Geologist PUBLICATIONS AND RECORDS George E. Ekblaw, Ph.D., Geologic Editor Chalmer L. Cooper. M.S., Geologic Editor Dorothy E. Rose, B.S., Technical Editor Kathryn K. Dedman, M.A., Asst. Technical Editor Alma R. Sweeny, A.B., Technical Files Clerk PoRTi.A. Allyn Smith, Research Assistant Meredith M. Calkins, Geologic Draftsman Leslie D. Vaughan, Asst. Photographer Dolores Thomas Sims, B.A., Geologic Clerk Special Staff to Aid in the War Effort Gil and Gas Resources Earle F. Tay'lor, M.S., Asst. Geologist Arnold Brokaw, \LS., Spec. Asst. Geologist M. W. PuLLEN, Jr., M.S., Spec. Asst. Geologist Paul K. Sims, M.S., Spec. Asst. Geologist John A. Harrison, B.S., Spec. Research Assistant Underground Water Geology Carl A. Bays. Ph.D., Spec. Geologist C. Leland Horberg, Ph.D., Spec. Asst. Geologist Stewart Folk, \LS., Spec. Asst. Geologist Ernest P. DuBois, B.S., Spec. Asst. Geologist Robert R. Storm, A.B., Spec. Asst. Geologist Paul Herbert, Jr.. B.S., Spec. Asst. Geologist Charles G. Johnson, A.B., Spec. Asst. Geologist Consultants: Ceramics, Cullen W. Parmelee, M.S., D.Sc, and Ralph K. Hursh. B.S., University of Pleistocene Invertebrate Paleontology, Frank Collins Baker. B.S.. University of Illinois; Mechanical Engineering. Seichi Konzo, M.S., University of Illinois. Topographic Mapping in Cooperation with the United States Geological Survey. This Report is a Contribution of the Industrial Minerals Division. \pril 15, 1942 Digitized by the Internet Arciiive in 2012 witii funding from University of Illinois Urbana-Champaign http://archive.org/details/feldsparinillino79will CONTENTS Page Abstract 7 Introduction 7 Acknowledgments 8 Procedure 8 Samples 8 Sieve analyses 9 Determination of acid-soluble material 9 Mineral analyses 10 Relation of grain size and composition to flotation and agglomerate tabling 11 Grain size 12 Mineral composition 12 Selection of deposits 13 Types of deposits 15 Dune sand 15 River sand and gravel 19 Outwash sand and gravel 21 Lake and beach sand and gravel 22 Preglacial sand and gravel 23 Sandstone 23 Glacial till 23 Possible advantages and disadvantages of the various types 25 Description of deposits 27 Chicago area 27 Kankakee area 29 Lacon area 33 Havana area 36 Rockf ord area 41 Prophetstown area 43 Savanna area 46 Oquawka area 48 Mississippi, Illinois, Ohio, and Wabash rivers 50 Other areas 51 TABLES Page 1 Description of samples 53 2 Sieve and mineral analyses 57 3 Approximate percentage of feldspar in various types of Illinois sands 13 4 Guide to the selection of Illinois sand deposits 14 5 Chemical analyses of dune sands 17 ILLUSTRATIONS Figure Page 1 Sand and gravel areas of Illinois 24 2 Locations of the map-areas, of samples collected outside the map-areas, and of samples from rivers 26 3 Sand and gravel deposits in the Chicago area 28 4 Sand and gravel deposits in the Kankakee area 30 5 Topographic map of a typical area of sand dunes in the Kankakee map-area. ... 32 6 Sand and gravel deposits in the Lacon area 34 7 Sand and gravel deposits in the Havana area 37 8 Topographic map of a typical area of sand dunes in the Havana map-area , 38 9 Sand and gravel deposits in the Rockf ord area 40 10 Sand and gravel deposits in the Prophetstown area 42 11 Topographic map of a typical area of sand dunes in the Prophetstown map-area. . 44 12 Sand and gravel deposits in the Savanna area 47 13 Sand and gravel deposits in the Oquawka area 49 [6] FELDSPAR IN ILLINOIS SANDS BY H. B. WiLLMAN ABSTRACT EXTENSIVE DEPOSITS of sand in Illinois contain 20 per cent feldspar, and some deposits contain more than 30 per cent. As no feldspar is mined in the State or in the Middle West, but con- siderable tonnages are shipped in from such distant states as Colorado, North Dakota, and North Carolina, it appears that feldspar might be produced profit- ably from Illinois sands if an economi- cal process for separating feldspar of commercial grade from the sand can be developed. The fact that feldspar can be separated from crushed granite by flotation suggests that feldspar possibly can be separated from the Illinois sands. In view of the foregoing, a two-fold investigation was undertaken by the Illinois Geological Survey to determine : (1) the extent and nature of the Illinois feldspar-bearing sands, and (2) the most economical methods of separating and preparing commercial grades of feldspar from the sands. This report covers the first portion of the investigation, describes the distribu- tion and size of Illinois sand deposits, and gives the results of sieve and min- eral analyses of more than a hundred samples representing typical deposits throughout the State. It shows that enormous deposits of feldspar-bearing sands occur in many parts of the State, especially the northern and western parts. Much of the feldspar-bearing sand has little or no present commercial use. The types of materials investigated were dune sands, glacial outwash sand and gravel, river sand, lake and beach sand, preglacial sand, and sands pro- duced by crushing sandstones. The sand- stones and preglacial sands were found to contain comparatively little feldspar. but the other types commonly contain 15 to 25 per cent feldspar with a few sands containing more than 30 per cent. Data regarding the percentage of feld- spar in the different types of sand are summarized on page 13, a classification of Illinois sand deposits on the basis of grain size and carbonate content is given on page 14, and a summary of the pos- sible advantages and disadvantages of the various types of sands as sources of feldspar is presented on page 25. INTRODUCTION The state of Illinois has enormous de- posits of dune, river, and glacial sands which at present have little commercial use. During the course of studies to find additional uses for these sands it was discovered that many of them contain as much as 20 per cent and some more than 30 per cent feldspar. The possi- bility that these sands might provide a new commercial source of feldspar of- fered a promising field for investigation, especially as large quantities of feldspar produced from pegmatite deposits in Colorado, South Dakota, and North Carolina and other Eastern States are used in Illinois and the Middle West in the manufacture of glass, pottery and enamels. Certain features of the sand deposits and the present feldspar industry favor the use of the sand as a source of feld- spar, namely : (1) The cost of mining sand is low as compared with that of pegmatite de- posits which require drilling, blasting, crushing, and in many cases hand- sorting. (2) The feldspar in the sand is of such grain size that for some uses it would require no grinding. The 200- [7] 8 FELDSPAR IN ILLINOIS SANDS mesh commercial grades could be pro- duced from sand with less grinding than from pegmatite feldspar. (3) The cost of the sand should be low because large areas of sand in Illi- nois are of relatively low value for agri- culture. (4) It is possible that the sand from which the feldspar has been removed may find some use, and that the mag- netite, ilmenite, and other minerals oc- curring in small amounts in the sands may have value as by-products. (5) Production of feldspar near the consuming centers of the Middle West would save freight charges. The cur- rent freight charge from western ship- ping points to Chicago is reported to be $7.37 a ton. (6) Because of the low cost of mining the sand and the comparatively low freight charges probable on feldspar to Middle West consumers, a considerable margin is available for separating the feldspar from the sand. (7) It has recently been demonstrated that feldspar can be separated from quartz by froth flotation and agglomer- ate tabling.^ (8) Recent technical advances in the methods of identifying feldspar make it possible to determine rapidly the ap- proximate quantity of feldspar in num- erous deposits. The quality of the feldspar which can be produced commercially from the Illi- nois sands is, of course, a primary con- sideration. Although the final answer to this question cannot be given at pres- ent, preliminary experiments by the Geochemical Section of the Survey in- dicate that it is possible to produce by laboratory methods a feldspar concen- trate which is as low in iron oxide and as high in alumina as most commercial feldspars. The feldspar so separated made a crystal glass. For these reasons an investigation was undertaken by the Illinois Geological Survey to determine, (1) the amount of feldspar and other minerals in the sands ^ O'Meara, R. G., Norman, J. E., and Hammond, W. E., Froth flotation and agglomerate tabling of feldspars: Am. Ceramic Soc. Bull., vol. 18, pp. 286-292, 1939. and the general distribution and size of the deposits, and (2) the quality of the feldspar and the best commercial meth- ods of separating it from the other con- stituents of the sands. The first phase of the study has been conducted by the Industrial Minerals Division of the Geo- logical Resources Section of the Survey and the second is being carried out by the Industrial Minerals Division of the Geochemical Section. This report gives the results of the first phase of this investigation and re- lates to resources. ; Acknowledgments This investigation was made under the supervision of J. E. Lamar, geo- logist and head of the Industrial Min- erals Division. Robert R. Reynolds as- sited in the field and laboratory studies. Other members of the Survey staff were consulted on various phases of the inves- tigation, especially J. S. Machin on the separation and quality of the feldspar, R. E. Grim on the problems in miner- alogy, and George E. Ekblaw on the dis- tribution of sand and gravel deposits. The maps of the sand and gravel de- posits are compiled from published re- ports and unpublished maps in the files of the Illinois Geological Survey. The county soil maps of the University of Illinois Agricultural Experiment Station were used in some areas. PROCEDURE Samples Because of the large number of ex- tensive sand deposits in Illinois, samples were collected from the various types of deposits in different parts of the State. After these samples had been studied additional samples were taken to supply further data about the most promising deposits. Samples of about 5 pounds each were collected from road- cuts, outcrops, pits, and auger borings. Because of inadequate exposures, it was usually not possible to secure samples from the entire thickness of the sand in any deposit. The samples of river sand were mostly obtained by combining small samples collected at many places on the surface PROCEDURE of a bar or beach exposed at low water. Therefore they do not represent any great thickness of sand, but they indi- cate the nature of the sands currently handled by the rivers. The location, character, thickness sam- pled, and thickness of the overburden of the samples are given in table 1, (p. 53). Sieve Analyses In the laboratory the grain size and mineral composition of the samples were determined and the results are given in table 2, pages 57-87. A preliminary ex- amination of the pebbly sands and the gravels showed that the material coarser than 8-mesh contained comparatively little feldspar, and the feldspar present in material coarser than 8-mesh occurred mostly in mineral aggregates which are largely fragments of igneous and meta- morphic rocks. In a commercial process any material coarser than 8-mesh, and perhaps even somewhat finer-grained material, would probably be screened out and discarded, or finer-grained sands would be used. Consequently material coarser than 8-mesh was sieved from the samples, its percentage was determined, and the sieve analyses were made on the material finer than 8-mesh by the follow- ing procedure. The entire sample was quartered to a 50- or 100-gram sample depending on the character of the material. If the sample was noncalcareous and origin- ally contained no material coarser than 8-mesh, a 50-gram sample was used. If it was calcareous, or if it originally con- tained some material coarser than 8- mesh, and was therefore relatively coarse, a 100-gram sample was used. The accurately weighed samples were ag- itated in water with a motor-driven malted-milk stirrer for about five min- utes. They were then wet-sieved on a 270-mesh sieve, dried, and weighed. From the loss in weight the percentage of material finer than 270-mesh was cal- culated. The material which was re- tained on the 270-mesh sieve was then sieved on Tyler standard sieves, rang- ing from 10- to 270-mesh (listed in table 2), using a rotap shaker for 15 minutes. Usually a little material passed the 270-mesh sieve and its amount was added to the amount of material finer than 270-mesh previously determined by washing. The results of these sieve analyses are recorded under Condition A in table 2. Determination of Acid-soluble Material To determine the percentage of car- bonates and iron oxides in the calcareous samples and to prepare the samples for later mineral determinations, the sieve fractions of the calcareous samples were recombined (omitting the material finer than 270-mesh) and the sample was di- gested in hydrochloric acid (1 part con- centrated acid and 2 parts water) until effervescence ceased. The residue was then filtered, washed, dried, and weighed, and the total per cent soluble was calculated. It is given as the total under Condition C in table 2. The sam- ple was then sieved again, using the same sieves as before, and the fractions were weighed. This sieve analysis is given under Condition B in table 2. From the loss of weight of each fraction the per cent of that fraction soluble in acid was calculated, as given under Con- dition C in table 2. The change in weight of fractions weighing less than 0.5 gram was not considered significant, and their percentage soluble is not recorded. This method gives a fairly accurate result for the total amount of acid- soluble material in the sample, but the solubility data for the individual sieve sizes are less accurate. In the latter a variable error arises from resieving, from the breakdown of aggregates when acid-treated, and from the insoluble res- idues in the calcareous grains. The last two errors cause the finer sieve sizes to show a lower solubility than actually occurs ; rarely they cause the finer sieve sizes to gain in weight after the acid treatment and resieving. The acid-soluble material consists largely of carbonates, mostly grains of limestone and dolomite, and of acid- soluble iron oxide, mostly stain of limo- nite on the grains. A small percentage of other acid-soluble minerals is also 10 FELDSPAR IN ILLINOIS SANDS present. As the amount of acid-soluble iron oxide is commonly between 0.5 and 1.0 per cent, the acid-soluble material over that amount is predominately carbonates. Mineral Analyses The mineral composition of the sam- ples was determined by mounting sand of selected sieve sizes on glass slides, etching and staining certain minerals to permit ready identification, and de- termining the percentage of the min- erals by counting the grains of each, using a binocular microscope. The pro- cedure was as follows: Two to four sieve fractions of most samples, more of a few samples, were selected for study. The fractions of the calcareous samples were ready for mounting after the sieve analysis, be- cause the iron oxide films on the grains had been removed in the acid treat- ment. The fractions of the noncal- careous samples, however, required di- gestion in hydrochloric acid to remove the iron oxide films. Each fraction was quartered, using a miniature Jones- type splitter, to a sample small enough to be mounted on a glass microscope slide. The slides were prepared by painting one surface with a thin solu- tion of Canada balsam in acetone and heating on a hot plate until the balsam when cool was hard but not brittle. The sand grains were spread thinly and evenly over the surface of the solid balsam. Then a very low bunsen-burner flame was passed directly but rapidly over the grains. This was repeated until the balsam melted and adhered to the grains, as shown by slightly jarring the slide. Too much heating will cause the balsam to cover the grains and interfere with later tests. The staining procedure'- consisted of covering the grains with a few drops of hydrofluoric acid (48 per cent) for one minute, gently washing off the acid by dipping the slide in water, then im- mediately covering the grains with a 10 per cent solution of freshly made sodium cobaltinitrite, and after a minute again washing the slide and permitting it to dry. It was then ready for study with a binocular microscope. Using a magni- fication that covered a field containing 25 to 50 grains, all the grains of each mineral in the field were counted. Usual- ly a row of adjacent fields completely across the slide, sometimes several rows, was counted, or until 500 to 1,000 grains were counted. Slides of grains coarser than 28-mesh usually did not contain 500 grains but on these slides more than 200 grains were counted. The percentages of the various min- erals, given in table 2, are all by number of grains rather than by weight. Al- though the feldspars range in specific gravity from a little higher to a little lower than quartz, they are mostly near enough to quartz that the percentage by number of grains is roughly equivalent to the percentage by weight. Chert and shale also have about the same percent- age by weight as by number, but the "heavy minerals" have specific gravi- ties ranging from about 3 to 5 and the percentage by weight is approximately 1.5 times the percentage by number of grains. After the slides were stained, it was possible to identify the principal con- stituents by the following characteristics. Quartz. — The quartz grains are very little affected by the staining operation and appear colorless and transparent. Potash feldspar. — The potash feld- spars are attacked by the hydrofluoric acid and are coated with a gelatinous film containing potassium salts. The potash reacts with the sodium cobaltini- trite to form a distinctive yellow precip- itate that coats the grains. Soda-lime feldspar. — The soda-lime feldspars are attacked by the hydro- fluoric acid and are given a white opaque fine-grained slightly lustrous surface. The high-lime feldspars and the more altered grains are more deeply etched than the high-soda feldspars. Chert. — Chert is readily attacked by the hydrofluoric acid and develops a deeply and irregularly etched surface. Although the chert is light gray or white 2 Gabriel, A., and Cox, E. P., A staining method for the quantitative determination of certain rock minerals: Amer. Mineralogist, vol. 14, pp. 29-0-292, 1929. GRAIN SIZE AND COMPOSITION 11 and opaque like the soda-lime feldspars, it has a dull surface. It commonly oc- curs in wedge-shaped or splinter-like g-rains. Some grains are not easily dif- ferentiated from highly altered soda- lime feldspars. Shale. — The fragments of fine-grained sedimentary rocks, which consist princi- pally of clay, silt, very fine sand, and mica in variable proportions, are listed in the tables as "shale." The shale grains have a wide range in composition but the most abundant type is composed largely of silt grains in a matrix of clay. The treatment with hydrofluoric acid deeply etches the clay in the shale grains so that the silt and sand grains — mostly quartz — stand in relief. Some of the stained shale fragments are peppered with small, yellow and white, opaque grains, probably feldspar. Heavy minerals. — Minerals with a spe- cific gravity greater than that of bromo- form (about 2.9) are commonly called "heavy minerals." Most of the heavy minerals in these sands are only slightly or not at all aifected by the staining pro- cess, and as most of them are colored they are easily recognized on the slides. Some colorless heavy minerals may be confused with quartz in the rapid count- ing method, but as the entire amount of heavy minerals is usually less than 3 per cent this is not likely to cause an im- portant error in the amount of quartz. Identification of most of the heavy min- erals on the stained slides is possible but because of their variety and relative scarceness in the slides not enough grains could be counted to give an accurate figure. They were therefore all grouped together. The heavy minerals of a few typical sands were separated from the original samples, using bromoform, and then mounted in Canada balsam on a glass slide and studied with a petro- graphic microscope. Other minerals. — Several minerals represented only by scattered grains, and a few grains which could not be readily identified, were counted as "others." Also in this category were mineral aggregates, principally frag- ments of igneous and metamorphic rocks, which occur on the coarser sieve sizes, mostly 28-mesh and coarser. These grains are frequently mixtures of quartz and feldspar. Aggregates which are al- most entirely feldspar were counted as potash or soda-lime feldspar according to which predominated. Limestone and dolomite. — The per- centage of limestone and dolomite, to- gether with generally less than 1.0 per cent acid-soluble iron oxide, is repre- sented by the total amount soluble in hydrochloric acid, given under Condi- tion C in table 2. RELATION OF GRAIN SIZE AND COMPOSITION TO FLOTATION AND AGGLOMERATE TABLING Recent experimental work by the U. S. Bureau of Mines-^ has demonstrated that the feldspar can be almost com- pletely separated from the other con- stitutents in granite or pegmatite by froth flotation and agglomerate tabling. Although it is not known that flota- tion and agglomerate tabling will ulti- mately be found to be the best methods for recovering feldspar from Illinois sands, these methods offer promise and therefore it is of interest to discuss briefly the grain size and mineral com- position of the sands in relation to the experimental work on the recovery of feldspar from granite. Much of the data given is probably pertinent to other processes which might be used for re- moving the feldspar from the sand. The problem of separating feldspar from natural sands is, in many respects, not greatly different from that of sepa- rating it from an artificial sand — such as a crushed pegmatite or granite. The crushed granite consists predominately of feldspar, 20 to 40 per cent quartz, and smaller quantities of mica, horn- blende, magnetite, and other compara- tively rare minerals. In the sands quartz predominates, feldspar is 15 to 25 per cent, mica is rare, but the other consti- tuents of the granite are present in small amounts. ' O'Meara, R. G., Norman, J. E., and Hammond, W. E., Froth flotation and agglomerate tabling of feldspars: Am. Ceramic Soc. Bull., vol. 18, pp. 286-292. 1939. 12 FELDSPAR IN ILLINOIS SANDS Experimental work is needed to dem- onstrate that the procedure used in the separation of the feldspars from the crushed granite is applicable to the natural sands. The Bureau of Mines found that feldspar-quartz mixtures from different mines do not always be- have the same in flotation and agglomer- ate tabling, probably because of differ- ences produced by weathering/ The surfaces of the feldspar grains in the sands may be more weathered than those in some granites and this may be of significance in relation to processing. Grain Size Commercial specifications for feldspar call for material as coarse as 20-mesh, and the Bureau of Mines found that the feldspar finer than 48-mesh could be separated by froth flotation and the feld- spar between 48-mesh and 20-mesh could be separated by agglomerate tabling. Many of the Illinois sands adequately cover this range of grain size, and the oversize of coarser sands could be crushed to pass 20-mesh. The 20-mesh grade, used by the glass industry, is produced by crushing to give the maximum amount of coarse material, but it has a range in grain size from 20- mesh to a fine powder. Although large- ly retained on 100-mesh, the 20-mesh grade contains powder which, partly be- cause it makes dust, is considered ob- jectionable. Feldspar produced entirely by froth flotation from Illinois sands would contain little feldspar coarser than 48-mesh, it would contain compara- tively little material passing 100-mesh, almost none passing 200-mesh, and it would be free of powder. If this product is satisfactory for the glass trade it would not be necessary to use agglom- erate tabling. If only froth flotation is used it would be advantageous to develop deposits of sand finer than 48-mesh, especially as the fine-grained deposits in any large sand area usually contain slightly more feldspar than the coarser sands. Illinois contains deposits of dune and river sands which are finer than 48-mesh, although generally these types of deposits contain * Op. cit., p. 289. some sand coarser than 48-mesh. If the coarser sands are used, the material re- tained on 48-mesh might be crushed to pass 48-mesh. If feldspar coarser than 48-mesh is re- quired agglomerate tabling alone might be used. Some deposits contain as much as 80 per cent^and between 20- and 48- mesh. The material finer than 270-mesh usu- ally forms a small percentage of the sands. It contains much clay and com- paratively little feldspar and would probably be washed out in conditioning the sand for flotation. It may also be desirable to wash out the 150-mesh and 200-mesh fractions in those sands which do not contain a large amount of these fractions, because these fractions contain a relatively large percentage of heavy minerals. The finer-grained material also contains a higher percentage of iron oxide than the coarser material. The analyses show that in most sands the chert, shale, and aggregates are con- centrated in the coarsest fractions, and it may be desirable to remove these frac- tions by screening. This screening may not be needed if the chert, shale, and aggregates remain with the quartz when the feldspar is separated and separation from the quartz is not desired. Mineral Composition As the flotation of feldspar is made in an acidic reagent,^ the noncalcareous sands are probably the more favorable for this process. Because of the large quantities of calcareous sands available, a number of samples were studied to de- termine the amounts and distribution of the carbonate grains and to see if such sands offered any special advantages which might justify removing the car- bonates. It was found that, in general, the greater the amount of carbonates the smaller the amount of feldspar, and con- sequently the highly calcareous deposits contain comparatively little feldspar. In many samples the distribution of the carbonates is such that it can be mate- rially reduced by removing the coarse fractions. Possibly the carbonate con- * O'Meara, R. G., Norman, J. E., and Hammond. W, E., Op. cit. p. 288. SELECTION OF DEPOSITS 13 tent of some very sliohtly calcareous sands is so low that an excessive amount of flotation reagents would not be re- quired to float the feldspar, but it seems probable that most calcareous sands would have to be processed to remove the carbonates before flotation of the feldspar. As previously noted the feldspar grains appear to contain internally as little iron oxide as the present commer- cial feldspars, so that the problem of producing a low-iron feldspar is largely one of removing the iron oxide stain, which commonly occurs as a thin coating en the grains, and of separating other iron-bearing minerals. The noncalcar- eous dune sands commonly contain more iron oxide stain than the other sands, some of which are almost white. Much of the iron oxide stain can probably be removed by abrasion. Iron oxide also occurs in the sands in grains of magnetite, ilmenite, limonite, hornblende, and augite, mostly in the finest sieve fractions. These minerals can possibly be separated from the quartz and feldspar magnetically or by some mechanical process depending on their relatively high specific gravity. In the dune sands the potash and soda-lime feldspar are about equally abundant, but in the other types of sands the soda-lime feldspar predom- inates, commonly in ratios of 2 :1 or 3 :1. The production of a feldspar with a high soda-lime content might be desir- able because of the lower fusion point of the soda-lime feldspar. On the other hand a high-potash content is desirable for certain kinds of giass. SELECTION OF DEPOSITS Development of a feldspar industry in Illinois must await demonstration that feldspar can be economically separated from the sands on a commercial scale. After this is achieved, selection of speci- fic deposits for development will require the consideration of many factors, such as the location of the deposit in relation to markets and transportation, the adaptability of the deposit to the process to be used, the percentage of feldspar and its quality when separated, the cost of the land, and the extent, thickness, and overburden of the deposits. In the selection of deposits the amount of feldspar is obviously an important consideration. Because the samples tested in the present investigation were of necessity distributed among many deposits, it was not possible to sample individual deposits in sufficient detail to reveal their variations in feldspar content. With a few exceptions, how- Table 3. — Approximate Percentage of Feldspar ix Various Types of Illinois Sands General location and type of deposit Number of samples Average per cent feldspar in samples tested Mississippi River sands below East St. Louis 6 4 14 7 10 18 2 2 4 4 3 6 20 30 Glacial outwash sand in Mississippi Valley 22 Fine-grained dune sand in Kankakee, Havana, and Chicago areas . . Mississippi River sands above East St. Louis 21 21 Medium- and coarse-grained dune sand in Savanna and Oquawka areas 20 Medium- and coarse-grained dune sand in Kankakee, Havana, and west part of the Prophetstown areas 18 Wabash River sand 18 Dune sand in Lacon area 16 Lake Michigan lake and beach sand 14 Ohio River sand 14 Illinois River sand 10 Dune sand in Rockford and east part of Prophetstown areas Calcareous glacial outwash sands and gravels 9 1-15 14 FELDSPAR IN ILLINOIS SANDS ever, the data available about each of the types of deposits are sufficiently con- sistent to permit a rough comparison of their relative feldspar contents (table 3). The variability of the feldspar within the deposits is probably such that differences of one or two per cent be- tween different deposits are probably not significant. Selection of a deposit will also in large part depend on the character of sand that is best adapted to the processing system to be used. Grain size as related to processing and trade requirements and the relative cost of processing cal- careous and noncalcareous sand may be as important as the total percentage of feldspar, especially as many of the de- posits differ only slightly in feldspar content. Some of the variations of the major deposits in grain size and compo- sition are summarized in table 4. The locations are by map-areas described later (pp. 26-52). Table 4. — Guide to the Selection of Illinois Sand Deposits Based on Variations IN Composition and Grain Size Characteristics Noncalcareous sand — 48-mesh — 20-mesh (mostly 48-, 65-, and 100- mesh) +20-mesh material, or — 20-mesh with high 28- and 35- mesh fractions Lowest possible iron-oxide content .... Type of deposit Dune sand in Kankakee and Havana areas Possibly Mississippi River sand, especially near East St. Louis Dune sand in all areas Outwash sands in Savanna and Oquawka areas Outwash sand in Savanna and Oquawka areas Sand screened from gravel in Savanna area Outwash sands in Savanna and Oquawka areas Slightly calcareous sand (less than 5 pei cent carbonates) — 48-mesh . —20-mesh . Mississippi River sand, especially south of East St. Louis Mississippi River sand Ohio River sand Calcareous sands (over 5 per cent car- bonates) — 48-mesh -20-mesh Lower parts of some sand dunes — probably can be used only with overlying noncalcareous sand — in Kankakee and Havana areas Mississippi River sand, especially south of East St. Louis (mostly less than 5 per cent carbonates) Lake Michigan beach and lake sand in Chicago area Lower parts of some sand dunes — probably can be used only with overlying noncalcareous sand — in Kankakee, Lacon, Havana, and Prophetstown area Illinois River sand Wabash River sand Sand screened from gravel deposits except along Missis- sippi Valley DVNE SAND 15 TYPES OF DEPOSITS The sand deposits of Illinois differ in composition and in manner of occur- rence. Their variations result from dif- ferences in the sources of the sand grains and differences in the ways in which they were transported to and deposited at the places where they now occur. Most of the sands are composed largely of quartz, but some feldspar is present in all of them. These minerals were formed originally in igneous rocks, which on the average contain about 60 per cent feldspar and about 12 per cent quartz. They were freed from the igneous rocks by weathering and erosion and then transported and deposited by various processes, especially by rivers, glaciers, and wind. The relative amounts of quartz and feldspar in the sands vary because feldspar is more easily decom- posed by chemical weathering, is softer, and has much better cleavage and there- fore breaks and wears more readily. As the deposits of similar origin have many characteristics in common they are dis- cussed together as ''types." These types may be classified as follows : Glacial outwash. — Most of Illinois was covered by glaciers during the Pleisto- cene period or ''Ice Age". These gla- ciers transported great quantities of rock debris, some of which w^as sorted by the glacial melt-waters and laid down in gravel, sand, silt, and clay deposits. Dime deposits. — Many of the large deposits of glacial sand and gravel are overlain by dunes of sand which was blown from the glacial deposits by the wind. River deposits. — The present rivers transport large quantities of sand and gravel which they temporarily deposit in bars along their channels, on the in- side of curves, behind jetties, and, dur- ing floods, on the floodplains. Much of the material carried by the rivers is de- rived from the glacial deposits by erosion. LaJte deposits — Large deposits of sand have been formed in Lake Michi- gan and along the beach of the lake b}' waves and currents. The sand is mostly derived from the glacial deposits. Preglacial sand and gravel. — Extreme southern Illinois contains extensive de- posits of sand and gravel which were formed during the Cretaceous and Terti- ary periods and are older than the gla- cial deposits but are not consolidated like the bedrock formations. Sandstones. — The sandstones are con- solidated sand deposits. The bedrock formations of Illinois contain many sandstone formations. The characters of the various types of sand deposits are discussed below. Dune Sand Illinois contains several large sand dune areas each of which contains hun- dreds of dunes. Many of the dunes have the shape characteristic of hills of wind- blown sand, namely gentle windward slopes and steep leeward slopes, but in some areas the dunes have long been in- active and because of slumping and erosion show only roughly the distinct- ive dune shape. The principal dune areas (fig. 1) are in Kankakee Valley, in Illinois VaUey between Peoria and Beardstown, in Rock River Valley below Dixon, and in Mississippi Valley near Savanna, Fulton, and Oquawka. These as well as other smaller areas of dunes occur principally along the major val- leys on large terraces of outwash sands and gravels, but locally they occur on the bluff's and adjoining highlands east of the terraces. In the latter areas they overlie glacial till or wind-blown silt (loess). On the terraces the dune sand usually grades into the underlj^ng water-laid sand which is distinguished only by the presence of scattered pebbles or beds of coarse sand. Thickness. — The thickness of the dune sand is usually about equal to the height of the dune. Exceptions occur (1) where the dunes are closely grouped in ridges and the wind-blown sands extend below the base of the dunes, (2) where the blow-outs between the dunes extend into the water-laid materials so that only the upper part of the dunes are wind- blown sand, and (3) where the wind- 16 FELDSPAR IN ILLINOIS SANDS blown sand covers the surface of bars or low rounded hills of water-laid sand. In most dune areas the dune sand thins to a trace at the margin of the dunes, and the sand underlying the flats between the dunes is water-laid. However, some of the flats are the floors of extinct lakes and are underlain by silt, clay, peat, or muck. In most of the major areas some dunes are 50 to 75 feet high, and dunes 25 to 50 feet high are common. Overburden. — Most of the dunes are covered with vegetation but there are usually a few blow-outs where the sand is uncovered, and adjacent to them are small dunes of bare sand. In the areas covered by vegetation the dune sand usually has a cover of 6 inches to 1 foot of dark brown silty sandy soil overlying 1 to 3 feet of silty sand or sandy silt which grades from very clayey and silty at the top to the typical dune sand at the base. Many of the dunes are forested or covered by thickets, and some now free of trees were formerly forested. As a result the roots of trees and shrubs are locally abundant in the upper 5 to 10 feet of sand. Grain size. — Although the sands in ad- jacent dunes usually have about the same grain size, there are noticeable dif- ferences in grain size between dunes in widely separated parts of the larger areas. Sieve tests of the coarser-grained dune sands show that the greatest per- centage of grains usually falls in the 35- to 48-mesh fraction, and in the finer- grained sands the greatest percentage falls in the 65- to 100-mesh fraction. About half of the samples of dune sands studied (table 2) have a greater percentage of grains in the 65- to 100- mesh fraction than in any other fraction. In the remainder the greatest percent- age falls in the 35- to 48-mesh or the 48- to 65-mesh fractions, about equally di- vided. Dunes on the upland areas are generally composed of finer-grained sand than those on the adjacent terraces. The dune sands are well sorted and usually have 65 per cent or more re- tained on two adjacent sieves. The dune sands contain on the average about 2 per cent of material finer than 270-mesh, mostly silt, but many contain less than 1 per cent. Samples which represent only the upper few feet of the deposits generally contain more silt than those representing the underlying sand, some as much as 12 per cent of material finer than 270-mesh. Carbonates. — The upper 5 to 10 feet of all the dunes is noncalcareous, and in most areas the dunes appear to be com- posed almost entirely of noncalcareous sand. Locally the core of the dunes is calcareous. The calcareous dune sands commonly contain 5 to 10 per cent car- bonates. In three samples tested the carbonates are uniformly more abundant in the finer sieve fractions, grading from 5 to 7 per cent in the coarser fractions to 25 to 30 per cent in the 150- to 200-mesh fraction. Iron oxide. — Most of the dune sands are light brown because the grains of sand and particles of clay have a thin coating of limonite (hydrated iron ox- ide). Chemical analyses of several samples of the sand from the Kankakee area show that the iron oxide content is generally less than 1 per cent (table 5). The upper 2 to 4 feet of sand usually contains more limonite than that below. A sample (SR-9) from the fresh sand exposed in the blow-out in a dune about three miles north of Coal City contains only 0.48 per cent iron oxide, whereas a sample (M-2) from the upper 7 feet of the deposit in the highest part of the same dune (omitting the upper two feet of silty sand and soil) contains 0.91 per cent iron oxide. These amounts in- clude not only the limonite staining the grains but the iron oxide present in heavy minerals and as inclusions in the quartz grains. Another sample (24) from the Coal City area, representing about 30 feet of sand, contains 0.65 per cent ferric oxide. Digesting the sand in hydrochloric acid lowered the ferric oxide to 0.13 per cent, indicating that 0.52 per cent ferric oxide is present as limonite or other hydrated iron oxide and that the balance occurs in certain of the heavy minerals and in inclusions in the quartz grains. BIJNE SAND Table 5. — Chemical Analyses of Dune Sands 17 Sample No.": 17 19 20 24 SR-9 M-2 Si02 1.00 89.88 0.25 4.57 1.12 0.29 0.65 0.76 1.83 0.09 0.19 0.54 0.82 92.37 0.14 3.28 0.65 0.21 0.53 0.60 1.49 0.06 0.15 0.44 93.7 3.94 0.48 0.29 0.42 1.18 0.51 0.05 0.22 91.37 Ti02 0.22 AloO^ 3.63 Fe203 0.99 MffO 0.25 CaO 0.51 Na20 55 K2O 1.50 H2O+ H2O— 0.04 CO2 0.50 Loss on ignition 0.60 Totalb 99.89 99.71 100.11 99.61 a. Locations of samples 17, 19, 20, and 24 are given in table 1. Sample SR-9 was collected from sand exposed in a blow-out in NE. cor. SE. 14, NE. i/i sec. 24, T. 33 N., R. 8 E. (Grundy County). Sample M-2 was collected from a small pit in the top of the same dune as sample SR-9 and represents 7 feet of sand omitting' the upper 2 feet of soil. b. H2O — and CO2 are not included in total. Another portion of the crude sample 24, from which the 4 per cent of material finer than 100-mesh was screened, con- tains 0.58 per cent ferric oxide, showing that the finer material contains a higher percentage of ferric oxide. In many deposits the upper 2 to 4 feet of sand is dark brown, the color gradu- ally becoming lighter toward the base of the zone. Below that some deposits con- tain irregular wavy bands of light and brown sand, the brown bands ranging from 1 to 4 inches thick and being sep- arated by a few inches to a foot or more of light-colored sand. The dark bands appear to be slightly more silty than the light bands but in general there is little textural difference. When dry the dark bands become comparatively hard. The more recently formed sand dunes do not have this banding. Quartz. — The average quartz content of the dune sands is 75 per cent, most of the sands containing 70 to 80 per cent quartz. The percentage of quartz varies in the different sieve fractions of each sand. Usually the maximum amount is in the 35- to 48-mesh fraction of the coarser-grained sands and in the 48- to 65-mesh fraction of the finer-grained sands. The decrease in the amount of quartz in the coarser fractions results from the rapid increase in abundance of shale, chert, and aggregates in these sizes. In the coarsest fraction the quartz may be as low as 50 per cent. The de- crease in the amount of quartz in the finer fractions results from the increase of feldspar and heavy minerals. Most of the quartz grains are colorless and clear. They are usually coated with a thin film of limonite. Some quartz grains contain small black inclusions of magnetite and consequently are in- cluded in extractions of the magnetic minerals. As a whole, the quartz grains are subangular but the smaller grains are predominately angular and many of the larger grains are well rounded. Feldspar. — Dune sands range in feld- spar content between extremes of 8 and 29 per cent. The 47 samples of dune sand examined contained an average of 18 per cent feldspar. The analyses show that with few exceptions the amount of feldspar in each sample increases in the finer sieve fractions of the samples. The 35- to 48-mesh and coarser fractions com- monly contain 10 to 18 per cent feld- spar, the 48- to 65-mesh contains 12 to 20 per cent, the 65- to 100-mesh contains 16 to 25 per cent, and the 100- to 150- mesh and finer fractions contain 20 to 30 per cent. A few samples from the upper Rock River Valley are unusually low in feldspar and contain less than the above. The deposits of fine-grained 18 FELDSPAR IN ILLINOIS SANDS sands have a higher feldspar content than the coarser-grained sands, especi- ally when comparing the sands in any one area. Twenty-four samples which have the highest percentage of sand in the 65- to 100-mesh fraction contain an average of 20 per cent feldspar, 10 samples with the highest percentage in the 48- to 65-mesh fraction average 17 per cent feldspar, and 13 samples with the highest percentage in the 35- to 48- mesh fraction average 15 per cent feld- spar. The coarser sieve fractions of the fine-grained sands contain a little less feldspar than the same sizes in the coarser-grained sands, but the higher total feldspar in the finer-grained sands results from the higher percentage of sand on the sieve sizes with higher feld- spar content. In most of the samples studied the feldspar is nearly uniformly divided be- tween the potash and soda-lime feld- spars, although when there is any differ- ence the soda-lime feldspars are usually the more abundant. The grains of pot- ash feldspar are mostly clear and glassy and only a small percentage are clouded with alteration products. Many of the grains of soda-lime feldspar are also clear but a large proportion of them are cloudy and many are opaque and con- siderably altered. There is no readily apparent difference in the extent of al- teration of the feldspar in the calcareous sands and in the noncalcareous sands overlying them. It appears therefore that the alteration of the soda-lime feld- spars was accomplished previous to ac- cumulation in the dunes. Shale. — Most of the dune sands con- tain 2 to 3 per cent shale, but some samples contain less than 1 per cent and one sample contained 7 per cent. The shale is most abundant in the coarse fractions of the samples. The amount almost invariably decreases uniformly in successively finer sieve fractions and very little shale occurs in the sand finer than 100-mesh. Chert. — Chert is present in nearly all the dune sands. It usually totals less than 1 per cent, but one sample contains 3 per cent. The chert is almost entirely in the coarser fractions of the sand. Although chert may comprise as much as 10 to 15 per cent of the material coarser than 28-mesh, material of this size usually forms less than 5 per cent of the coarsest-grained dune sands. Most of the chert is in the fractions coarser than 48-mesh, and the amount decreases progressively in the fine sizes, decreasing more sharply than does the amount of shale. Only a few chert grains occur in the 65- to 100-mesh frac- tions, and they are rare in the finer fractions. Heavy minerals. — Most dune sands contain 1 to 2 per cent, rarely as much as 4 per cent, heavy minerals by weight. About half the heavy minerals separated from two samples from the Havana area are black opaque metallic grains, mostly ilmenite and magnetite, the former pre- dominating. The mineral analyses of the heavy minerals separated from two samples are as follows: Per cent by weight Mineral Sampl e42 30 20 30 10 1 3 1 1 2 Sample 44 Ilmenite 44 Magnetite 12 Amphiboles and pyrox- enes Garnet Light-colored aggregate? Zircon Epidote Rutile 26 8 3 3 1 I Leucoxene Tourmaline Corundum Titanite Leucoxene, chlorite, tour- maline, others Kyanite, topaz, apatite, rutile, others 2 Although the percentages of the min- erals were determined by counting grains, they were converted to per cent by weight on the basis of the average specific gravity of the mineral or the mineral group. The percentages are only approximate because of a consider- able variation in grain size. The zircon and most of the epidote grains are very small, and most of the amphibole, pyrox- ElVER SAND AND GRAVEL 19 ene, and garnet grains are relatively large. The ilmenite and magnetite grains vary in grain size but are mostly smaller than the amphibole, pyroxene, and garnet grains. Two samples of the beach sands of glacial Lake Chicago, from which the overlying sand dunes have been derived, contain the following heavy minerals^ : Near Evanston — hornblende is abund- ant ; chlorite, epidote, garnet, hypers- thene, magnetite, tourmaline, and zircon are common ; augite, diopside, and stau- rolite are rare. Near Harvey — chlorite, garnet, and hornblende are abundant ; hypersthene and magnetite are common ; augite, diopside, epidote, tourmaline, and zircon are rare ; corundum, ensta- tite, and rutile are very rare. The heavy minerals are rarely more than a trace in the sand coarser than 65-mesh but the 65- to 100-mesh fraction commonly contains 1 to 3 per cent, the 100- to 150-mesh fraction contains 2 to 5 per cent, and that finer than 150-mesh contains more than 5 per cent. Although the coarser-grained sands usually have a larger amount of heavy minerals in the 48- to 65-mesh and the 65- to 100-mesh fractions than do the finer dune sands, the finer-grained sands have a greater total percentage of heavy minerals. Others. — Because of the variety of un- identified grains, miscellaneous rare grains, and mineral aggregates, there is not a consistant increase or decrease in abundance of the grains classed as ''others" through the different sieve fractions as there is in most of the minerals. Many sands contain 1 or 2 per cent of ''other" grains. The ma- terial coarser than 28-mesh in the coarser-grained sands frequently con- tains 2 to 6 per cent of mineral aggre- gates (principally igneous and metamor- phic rocks) which are included under "others." Chemical composition. — The chemical analyses of four samples of dune sands in the Kankakee district (table 5, p. 17) « Lamar, J. E., and Grim, R. E., Heavy minerals in niinois sands and gravels of various ages: .jour. Scd. Petrology, vol. 7, pp. 78-83, 1937. The sample near Evanston was collected in the center sec. ."3, T. 42 N.. R. 13 E., that near Harvey in the NE. U NW. M NW % sec. 4, T. 35 N., R. 14 E. show that alumina varies from 3.28 to 4.57 per cent. As the samples contain little clay and shale the analyses indi- cate a feldspar content of approximately 16 to 22 per cent, assuming the average alumina content of the feldspar is 20 per cent. This checks closely with the data obtained from the mineral analyses. River Sand and Gravel Mississippi, Illinois, Ohio, and Wa- bash rivers transport large quantities of sandy gravel and sand that is tem- porarily deposited in bars along their channels and on their floodplains. The actual river beds do not consist entirely or continuously of sand ; extensive areas consist of silt or silty clay. Bars of sand and gravel in the river beds are com- monly covered with a few inches of silt. At low water many large sand flats are exposed, especially along Mississippi River where bars more than a mile long and one-fourth mile wide are common. Jetties have been built at many places along the rivers to maintain a navigable depth in the main channel, and enorm- ous quantities of sand have accumulated behind the jetties. Some of these de- posits are exposed at low water but many of them are now continuously sub- merged by ponding of the rivers behind dams. Thickness. — Some of the sand deposits in the rivers are more than 50 feet thick in places. Because of the varying cur- rents in the river, the grain size of the sand deposited frequently changes so that the deposits probably do not con- tain a great thickness of sand of uniform grain size at one place. Although the sand on the surface of some large bars exposed at low water is comparatively uniform in grain size, usually not more than a foot or two of this sand is ex- posed. As much as 10 feet of uniform sand has been observed. The sand in bars on the floodplains is usually thin. The floodplain deposits locally contain a considerable thickness of sand and gravel, but these are usually lenticular and are interbedded with silt. Overburden. — The bars along the rivers usually have no overburden, but 20 FELDSPAR IN ILLINOIS SANDS any bar may be covered with silt during the receding stage of a flood. Grain size. — Sand with almost any grain size desired can be found along the rivers. Most of the sand observed is medium or coarse-grained, usually con- tains some grains coarser than 8-mesh, and commonly the 35- to 48-mesh sieve fraction has the highest percentage (table 2). However, along Mississippi River south of Alton there are large bars in which the exposed sand has the highest percentage in the 65- to 100- mesh fraction. The coarser-grained river sands have a wide range of grain-size distribution. Whereas 65 per cent of most of the dune sands is retained on two adjacent sieves, it requires three or four adjacent sieves to give a similar total for the river sands. The finer-grained river sands are better sorted and are similar in grain-size dis- tribution to the dune sands. The amount of material finer than 270-mesh is highly variable but some of the sand is almost free of this material. Nine of 13 samples of Mississippi River sand contain less than 1 per cent of ma- terial finer than 270-mesh and average only 0.4 per cent. The other four sam- ples, mostly very fine-grained sands, range up to 11.6 per cent finer than 270-mesh. Carbonates. — Most of the river sands are slightly calcareous and some are highly calcareous. The samples of Illi- nois River sand contain 5, 10, and 12 per cent acid-soluble material, Wabash River sand 9 and 23 per cent, and Ohio River sand 3 and 4 per cent. One sample of Ohio River sand was noncal- careous. Most of the Mississippi River samples contain 1 to 2 per cent acid- soluble material but several samples are not calcareous. The coarse sieve frac- tions of the river sands contain the high- est amount of carbonates, as much as 30 per cent in the more calcareous samples, but the amount decreases on successively finer sieves to a minimum on the sieve fraction with the highest percentage of sand or on the size immediately below it. There is usually a slight increase in carbonates in the finer sieve sizes. Iron oxide. — The river sands are mostly lighter gray in color and appar- ently have little iron oxide stain on the surface of the grains. Some of the heavy minerals consist of or contain iron oxide, but the quantity in heavy minerals is probably less than 1 per cent at most places. The river sands contain less iron oxide stain on the grains but more in heavy minerals than the dune sands. Quartz. — The total quartz content varies from 50 to 80 per cent. The greatest percentage of quartz is usually in the 35- to 48- or 48- to 65-mesh frac- tions, decreasing rapidly in the coarser fractions because of the increase in shale, chert, and aggregates, and de- creasing slightly in the finer fractions because of the increase in feldspar and heavy minerals. The quartz is mostly clear and subangular. Feldspar. — The average feldspar con- tent of the river sands tested is 21 per cent but the sands of different rivers differ in feldspar content. The Illinois River sands average 10 per cent ; Ohio River sands, 15 per cent ; Wabash River sands, 18 per cent; and Mississippi River sands, 25 per cent. The sands with the highest feldspar content were found in Mississippi River south of East St. Louis, where three samples contain 32 to 34 per cent feldspar. In most of the sands there is about twice as much soda- lime feldspar as potash feldspar. In many sands the amount of potash feld- spar in the various sieve fractions is fairly uniform, although usually there is a slight decrease in the amount in the finer fractions. In the coarser-grained sands the soda-lime feldspars usually occur in fairly uniform amounts in the 28- to 35-mesh, 35- to 48-mesh, and 48- to 65-mesh fractions, which comprise the bulk of the samples, but both the coarser and finer fractions contain a higher amount of soda-lime feldspar. The finer- grained sands as a whole contain a higher percentage of feldspar than the coarser-grained. Shale. — The river sands all contain some shale, commonly 2 to 4 per cent but locally as much as 10 per cent. Most of the shale occurs in the coarser fractions. OUTWASH SAND AND GRAVEL 21 Chert. — Chert is present in all the river sands but in more variable quanti- ties than the shale. The range is from a trace to 7 per cent with the average about 2 per cent. Chert occurs mostly in the coarse fractions. Heavy minerals. — Most of the coarse- and medium-grained river sands con- tain less than IV2 per cent heavy min- erals, but the fine-grained sands contain 2 to 4 per cent. Other minerals. — The river sands usu- ally contain 2 to 10 per cent of variable material classified as "others." In gen- eral, the river sands contain a slightly higher amount of "other" grains than the dune sands. OuTWASH Sand and Gravel During the Pleistocene or "Glacial" period most of Illinois was covered by glaciers. As the glaciers melted the melt-water was concentrated into streams that carried rock materials that had been incorporated in the glaciers and later deposited them in or below the ice, in plains along the ice front, or in valleys leading away from the ice. The coarse-grained materials were mostly deposited near the ice, the finer-grained materials at greater distances. These deposits as a group are called "out- wash ' ' deposits. Large outwash deposits of sand and gravel are especially com- mon in the north part of the State (fig. 1) and also in the major valleys along which the glacial rivers carried sand and gravel many miles from the ice front. Most of the glacial-river deposits now occur in terraces at various levels above the present rivers. Thickness. — Glacial outwash deposits vary from a few inches to more than 200 feet thick. In the large terraces along the major valleys they commonly extend below the present river levels and are more than 100 feet thick at many places. Overburden. — Many large outwash deposits have an overburden of silt and soil from 1 to 5 feet thick. Some depos- its locally have an overburden of dune sand and others have a thick cover of glacial clay and silt (till). Grain size. — The outwash deposits vary in grain size from clay to coarse gravel. Some large outwash deposits are composed almost entirely of sand, but most of the sand deposits contain some pebbles and usually beds of gravel. All gravel deposits contain a consider- able amount of sand mixed with the pebbles, and many of them contain about 50 per cent of sand. As the sand might be easily screened from the gravel deposits and as some gravel deposits being worked have an excess of sand which is washed back into the pits, several samples of gravel repre- senting outwash of diiferent glaciers were included in the study to determine their feldspar content. Many important commercial deposits were not sampled but the samples tested (table 2) repre- sent the major types of deposits of dif- ferent age and origin. Because of the comparatively small size of the samples collected it is believed that the amount of material coarser than 8-mesh as re- ported is probably somewhat low for most of the gravel deposits. Carbonates. — The samples collected from outwash deposits in terraces along Mississippi Valley are noncalcareous, and the material coarser than 8-mesh consists almost entirely of igneous and metamorphic rocks with some quartz, siltstone, and sandstone. Elsewhere in Illinois the glacial outwash is nearly all calcareous, and the material coarser than 8-mesh consists largely of limestone and dolomite with small amounts of igneous and metamorphic rock, sandstone, silt- stone, and shale. In the portion of the samples between 8- and 270-mesh the per cent soluble in acid varies greatly but the amount is usually more than 10 per cent, is locally as much as 75 per cent, and averages 27 per cent in the 18 samples studied. In each sample the amount of carbonate decreases progres- sively from a maximum in the coarser sand to a minimum usually in the 48- to 65-mesh or 65- to 100-mesh fractions and then increases in the finer sand. By screening out both the finer and coarser fractions the average amount in the sand could be materially reduced. Generally the coarser-grained sands have a higher 22 FELDSPAR IN ILLINOIS SANDS carbonate content than the medium- and fine-grained sands. Very fine-grained sands are frequently highly calcareous. This gradation results from the concen- tration of much of the quartz in its original source in the grain sizes between 20- and 100-mesh, causing the quartz sand to dilute the limestone and dolo- mite grains in this grain size. Quartz. — Many outwash sands contain 40 to 70 per cent quartz but the very coarse-grained sands and the sand washed from gravels contain less. The greatest percentage of quartz is usually in the 35- to 48-mesh or 48- to 65-mesh fractions. The outwash sands contain less quartz than the dune and river sands because of the greater percentage of carbonates. Feldspar. — The amount of feldspar in the calcareous outwash deposits is highly variable because of variations in the amount of carbonates and in the amount of materials coarser than 8-mesh which contain little feldspar. Most of the sand deposits contain 10 to 15 per cent feld- spar. Some of the gravel deposits as a whole contain as little as 1 per cent feldspar, considering only the feldspar in the 8- to 270-mesh frac- tion as recoverable, and most of them contain less than 10 per cent feld- spar. However, the 8- to 270-mesh ma- terial itself contains an average of 12 per cent feldspar. When the acid-soluble materials are removed from this fraction the remaining material contains 12 to 23 per cent feldspar, averaging 18 per cent. Therefore it appears that the out- wash and dune sands have about the same feldspar content, comparing non- calcareous material of comparable grain size. The noncalcareous outwash deposits along Mississippi Valley contain more feldspar than the other outwash depos- its, four samples containing 21 to 23 per cent feldspar. The outwash sands commonly contain 2 or 3 times as much soda-lime feldspar as potash feldspar although in a few samples they are about equal. The amount of potash feldspar commonly increases in the finer sieve fractions. The amount of soda-lime feldspar is more variable but commonly is lowest in the 28- to 35-mesh, 35- to 48-mesh, or 48- to 65-mesh fractions, increasing in abund- ance in both finer and coarser fractions. In the very coarse-grained sands the amount is usually slightly reduced in the coarsest fractions because of the abund- ance of aggregates. Shale. — The outwash deposits com- monly contain 2 to 10 per cent shale, most of which occurs in the coarse frac- tions. Chert. — Chert commonly forms 1 to 5 per cent of the outwash deposits. Most of the chert is retained on the 28-mesh and coarser fractions. The outwash de- posits along Mississippi Valley contain little chert. Heavy minerals. — Most of the outwash deposits contain less than 1 per cent heavy minerals. The heavy minerals are irregularly distributed and locally streaks of sand are dark colored because of the abundance of heavy minerals. Most of the heavy minerals are in the sand finer than 65-mesh. A study^ of tlie heavy minerals from many outwash deposits indicates that the following minerals are locally abundant : Augite, garnet, hornblende, and magnetite. The common minerals include chlorite, diop- side, epidote, hypersthene, tourmaline and zircon. Scattered grains of many other minerals are present locally. Others. — The outwash deposits con- tain 1 to 5 per cent of grains classified as ''others". They are mostly fragments of igneous and metamorphic rocks which are common in the coarse frac- tions. Lake and Beach Sand and Gravel Large deposits of beach and lake sands occur along and in Lake Michigan. The material ranges from gravel to fine sand. The one sample of lake sand studied (Sample 1, table 2) is a calcareous pebbly sand containing 21 per cent coarser than 8 mesh. The 8- to 270-mesh fraction contains 11 per cent of acid- soluble material. The whole sample con- tains 14 per cent feldspar but the 8- to ' Lamar, J. E., and Grim, R. E. Heavy m morals in Illinois sands and gravels of various ages, .Jour. Seel. Petrologv, vol. 7, pp. 78-83, 1937. PREGLACIAL SAXD AXD GRAVEL 23 270-mesh fraction contains 18 per cent feldspar, of which about two-thirds is soda-lime feldspar. The sample con- tains 8 per cent shale and 12 per cent chert which is considerably higher than in the outwash, river, and dune deposits sampled. One of three samples of beach sand is a pebbly sand and the other two are medium-grained sand similar to dune sand in grain size. All are calcareous, varying from 7 to 19 per cent soluble in acid. The two medium-grained sands contain 11 and 16 per cent feldspar, and the 8- to 270-mesh fraction of the pebbly sand contains 14 per cent feldspar. Another study of six samples of Illi- nois beach sands showed the heavy min- erals vary from 1.4 to 7.5 per cent by weight.^ The average mineral content of the six samples in per cent by number of grains is as follows : Magnetite and ilmenite 40.9 Augite 24.9 Hornblende 12.1 Leucoxene, etc 10.9 Garnet 5.5 Epidote 1-5 Diopside 10 Hypersthene 8 Zircon 8 Actinolite 2 Staurolite 2 Tourmaline Tr Titanite Tr Rutile Tr Kyanite Tr Biotite Tr Pyrite Tr In another study"-" one sample from the beach near Glencoe contains 1.4 per cent heavy minerals, and one from near Lake Bluff contains 9 per cent heavy miner- als. In the sample from Glencoe horn- blende and hypersthene are abundant ; augite, diopside, epidote, garnet, and magnetite are common; olivine is rare, and rutile and tourmaline are very rare. In the sample from Lake Bluff augite, diopside, hypersthene, and magnetite are abundant ; epidote, garnet, and horn- blende are common ; chlorite and ensta- tite are rare ; and kyanite, rutile, stauro- lite, topaz, and zircon are very rare. " Pettijohn. F. J. Petrography of the beach sands of southern Lake Michigan, Jour. Geol. vol. 39, pp. 432- 4o5. 1931. Preglacial Sand and Gravel Large deposits of sand and gravel ac- cumulated in the extreme southern part of Illinois during the Cretaceous and Tertiary periods (fig. 1). Four samples of these materials were examined. A sample of Eocene sand and two samples of Cretaceous sand contain only a few grains of soda-lime feldspar. One sam- ple of "Lafayette" (Pliocene?) sand contains less than 1 per cent of potash feldspar and 2 to 3 per cent soda-lime feldspar. Because of the very low feld- spar content of the samples examined, it is probable that the Cretaceous-Terti- ary deposits may be ruled out as a com- mercial source of feldspar. Sandstone The bedrock formations of Illinois contain many beds of sandstone, and the presence of grains of feldspar in them has long been recognized. In the pres- ent study hand-samples of many forma- tions were studied to determine the pos- sibilities of these formations as a com- mercial source of feldspar. Samples of New Richmond, St. Peter, Glenwood, Bethel, Cypress, Hardinsburg, Degonia, and Lick Creek sandstones contain a few scattered grains of feldspar but in all of them feldspar is much less than 1 per cent. A sample of Makanda sandstone contains about 2 per cent feldspar, and several higher Pennsylvanian sandstones contain 2 to 15 per cent feldspar. As the sandstones contain less feld- spar than the sand deposits, they are probably not important as commercial sources of feldspar. Glacial Till Most of the area of Illinois that was covered by the glaciers is mantled with glacial till, a deposit of silty clay con- taining sand grains, pebbles, and boul- ders. As many of the deposits of till contain a considerable amount of sand, and as the different glaciers carried ma- terials from different source areas, sev- eral samples of the sand washed from tills were examined to see if the deposits ^ Lamar, J. E., and Grim, R. E., Heavy minerals in Illinois sands and gravels of various ages, Jour. Sed. Petrology vol. 7, pp. 78-83, 1937. 24 FELDSPAR IN ILLINOIS SANDS \ WA \l\ " ^ J\ MeHENf^Y a\ LAKE. n(\\\\ PEPHENSOI SH\\\\ \V ^-^-^^ Fig. 1. — Sand and gravel areas of Illinois (excepting silica sand), VARIOUS TYPES 25 of any particular glacier contain an un- usual concentration of feldspar. If so, the outwash sand and gravel deposits of that o-lacier might have a higher feldspar content than the other outwash deposits. Two samples of Illinoian tills (105, 106, tables 1, 2) and three of Wisconsin till (102-104) were examined. The 8- to 270-mesh fractions of the Illinoian till samples, acid-treated to remove carbon- ates, contain 15 and 17 per cent feld- spar, and the same fractions of the Wis- consin till samples contain 15, 18, and 20 per cent feldspar. Although these data are too limited to be conclusive they suggest that the feldspar content of the tills is approximately the same. Possible Advantages and Disadvan- tages OF THE Various Types As it is uncertain what methods may be used in processing the sands and what chemical and grain-size specifica- tions they may impose on the sand, only a general consideration of the advant- ages and disadvantages of the various types of deposits is given. The problem of disposal of the sand after the feldspar is removed, if the sand cannot be sold, is an important consideration which de- pends more on conditions at the individ- ual deposit than on the type of deposit. If the waste sand is clean and fine- grained it may be easily blown about when dry and therefore require special handling in stock-piling. Deposits ex- cavated from below water might have an advantage if the waste sand can be re- turned to the pit. Some of the possible advantages and disadvantages of the various types are listed below: dune sands Possible advantages Noncalcareous Comparatively high feldspar content Uniform grain size Well-sorted Fine grain size Low clay content Large deposits Thin overburden Low-cost mininer Areas mostly of relatively low agri- cultural value Possible disadvantages Cores of dunes calcareous in some areas More iron oxide stain on grains than other types Clay dried on grains and more diffi- cult to scrub off RIVER sand Possible advantages High feldspar content High content of soda-lime feldspars Low iron oxide stain on grains Low clay content Clay not dried on grains and easily scrubbed off Large quantities of almost any desired grain size No overburden Production by low-cost dredging Mobility of operation if different grain size desired Large supply of water available for processing Low-cost water transportation Low original cost of sand Waste sand easily disposed of by re- turning to river Possible disadvantages Slightly calcareous Variability of individual deposits in grain size Shifting of deposits during floods River water at times may be too mud- dy for use in process Intermittent operation because of ice and floods OUTWASH sand AND GRAVEL Possible advantages Less iron oxide stain on grains than on noncalcareous dune sands Mississippi Valley deposits noncal- careous Mississippi Valley deposits have high feldspar content Possible disadvantages Calcareous, except in Mississippi Val- ley Lower feldspar content, except in Mis- sissippi Valley 26 FELDSPAR IN ILLINOIS SANDS SCALE & 10 15 20 2S 30 MILES Fig. 2. — Locations of the map-areas, of samples collected outside the map-areas, and of samples from rivers. CHICAGO AREA 27 Variable grain size Thicker overburden than dune sands Land usually more valuable than dune areas LAKE AND BEACH SAND AND GRAVEL Possible advantages Less iron oxide stain on grains than dune sands About same feldspar content as dune sands Low clay content Low original cost of sand Production by low-cost dredging Water available for processing Proximity to Chicago industrial dis- tricts Water transportation to lake ports Possible disadvantages Calcareous Variable in grain size Intermittent operation because of storms and ice PREGLACIAL SAXDS AND SANDSTONES Disadvantage Too low feldspar content DESCRIPTION OF DEPOSITS The most extensive deposits of sand and gravel in Illinois occur in the north part of the State. To show their general distribution the north part of the State was subdivided into the map-areas shown in fig. 2. Following is a brief description of the deposits in the map- areas and in the major rivers. Chicago Area The principal deposits of sand in the Chicago area occur in Lake Michigan and its beaches, in sand dunes and beach deposits along the shorelines of glacial Lake Chicago, and in outwash deposits which are widely distributed but especi- ally abundant along DesPlaines, Du- Page, and Fox valleys (fig. 3). LAKE SAND Large quantities of sand and gravel occur on the floor of Lake Michigran and material dredged from these deposits is extensively used in the building industry in Chicago. The one sample (1, tables 1, 2) of lake sand studied (p ) is a calcareous pebbly sand containing 14 per cent feldspar. The deposits on the lake bottom are principally sand but they vary in grain size from sand to gravel. Seven samples collected on a line from near shore at Jackson Park to 8.1 miles out in the lake consist of material largely between 32- and 115- mesh, but within this range some of the samples have as much as 85 per cent finer than 60-mesh and some have only 25 per cent.^*^ BEACH SAND Large deposits of sand occur in the beaches of Lake Michigan, esp-ecially north of Chicago, but because much of the beach is used for recreational and other purposes its availability as a source of sand is uncertain. As these sands are probably similar in composi- tion to those which might be dredged from the lake a short distance off shore, samples from the beach at Zion City (2) and Glencoe (4) were studied. The sample from Zion City is a pebbly sand containing 12 per cent feldspar. After removing the material coarser than 8- mesh, the proportion of which is highly variable along the beach, the sand con- tains 14 per cent feldspar. The sample from the beach at Glencoe contains 16 per cent feldspar. A study^^ of six sam- ples collected along the beach shows the sand is largely between 35- and 100-mesh in grain size, contains little fine sand and clay, and 10 to 15 per cent acid- soluble material. Between the present shore and the bluff north of Waukegan, in a belt one-half to one mile wide, many low ridges of sand occur along former shore lines of the lake. A sample (3) from one of these ridges near Zion City contains 11 per cent feldspar. This sample and one from the present beach at Zion were unusual in containing only 3 to 4 per cent potash feldspar. The ^° Hough, Jack L. The mechanical composition of the deposits of southern Lake Michigan: Uui/ersity of Chicago, Thesis, 1934. " Pettijohn, F. J. Petrography of the beach sands of Southern Lake Michigan : .Jour. GeoL V'oL 39, pp. 432- 455, 1931. ^8 FELDSPAR IN ILLINOIS SANDS R.5E R.5E 6 7 8 9 10 LEGEND ^PRINCIPAL AREAS CONTAINING AREA CONTAINING SCATTERED BEACH [\\\ OUTWASH DEPOSITS OF SAND ^^^ DEPOSITS OF SAND AND GRAVEL, IN ' ° ° AND GRAVEL K22i23 PART COVERED WITH SAND DUNES SCATTERED DEPOSITS OF SAND AND GRAVEL •5 LOCATION AND NUMBER OF SAMPLE SCALE Fig. 3. — Sand and gravel deposits in the Chicago area. KANKAKEE AREA 29 distribution of the sand ridges in the area north of Waukegan is shown on the topographic map of the Waukegan quadrangle/^ DUXE SAND Deposits of dune sand overlying beach sand occur at many places along old shorelines in the area formerly covered by ancient Lake Chicago/^ Most of the deposits are now covered by the resi- dential and industrial areas of Chicago and its neighboring cities and are not available for development. Probably the largest deposits still accessible occur south of Chicago near Lansing, but be- cause of the relativelj' high value of the land in this area and the thinness of the deposits, it is not certain that the}^ can be developed on a large scale as a source of feldspar. Dune sand overlies beach sand in a ridge extending from Lansing west to Thornton along Ridge road. The ridge is shown on the Calumet City quadrangle map. Four samples (6-9) of the dune sand are medium to fine sand, mosth' finer than 48-mesh with the maximum percentage on the 100-mesh sieve (one sample on 150-mesh). They contain 20 to 23 per cent feldspar, a percentage slightly higher than the average of all dune sands. The dune sand is gener- ally only 3 to 5 feet thick below the higher part of the ridge. It overlies slightly coarser-grained sand. In the higher ridges the upper 7 to 10 feet of the deposits is generally noncalcareous but on the margin of the ridges calcare- ous sand is only 3 to 4 feet deep. The largest areas without buildings are west of the Grand Trunk Railroad at Lansing in sees. 35 and 36, T. 36 N., R. 14 E. A sample (5) from another sand ridge about three miles north of Lansing con- tains 28 per cent feldspar, but the ridge has a paved road along its crest, and it is doubtful if a large-scale development could be undertaken in this area. *^ The topographic maps may be obtained at 10 cents each from the State Geological Survey, Urbaaa, Illinois. i^Alden, W, C, U. S. Geol. Survey Geol. Atlas, Chi- cago folio (No. 81) 1902. Bretz, J H. Geologj' of the Chicago Region, Ft. 1 — General: Illinois State Geol. Survev Bull. 65, plate 1. 1939. OUTWASH SAND AND GRAVEL Outwash deposits of gravel and sand are widely distributed (fig. 3) and of large size.^"^ They are highly calcareous and consequently are relatively low in feldspar. Four samples (10-13) of out- wash sand and gravel contain feldspar in amounts varying from 1 to 14 per cent, but after the acid-soluble materials are removed the 8- to 270-mesh fraction contains 16 to 23 per cent feldspar. Kankakee Area The Kankakee area (fig. 4) contains large deposits of dune sand and out- wash sand and gravel. DUNE SAND In the Kankakee area, sand dunes oc- cur principally in a broad terrace along Kankakee Valley, where they overlie glacial sand and gravel, and on the sur- face of a glacial lake bottom in Iroquois Valley, where they overlie glacial sands and silts. Because of the westerly winds some sand has been blown onto the up- land east of the Iroquois Valley area. The dunes are of all sizes and shapes. Many dunes southeast of Momence (fig. 5) are ridges elongated northwest to southeast and have a typical steep slope on the northeast or lee side and a com- paratively gentle slope on the southwest or windward side. In some areas, as north of Watseka, the dunes are less reg- ular in shape. The individual dunes are mostly grouped in more or less continu- ous ridges, in which there are 25 to 50 dunes in a square mile. Where the dunes are closely grouped the sand is continuous from one dune to the other, but where the dunes are more scattered, and especially where they are separated by broad flat areas, the inter- vening areas may be underlain by water- laid sand or gravel, by lake deposits of silt or peat, by glacial till, or locally by bedrock. " Bretz, .J H., op. cit. Fisher, D. .J., GeologA' and mineral resources of the Joliet quadrangle: Illinois Geol. Surrey Bull. 51, 1925. Trowbridge, A. C, Geology and geography of the Wheaton quadrangle: Illinois Geol. Survey Bull. 19, 1912. 30 FELDSPAR IN ILLINOIS SANDS PRINCIPAL TERRACE AND LAKE - BOTTOM AREAS CONTAINING SAND DUNES 1:: ;.■.-;■; I principal upland areas containing I-'"- •"•■1 sand DUNES 1° e » I PRINCIPAL AREAS CONTAINING OUTWASH 1 ^ ° ° ° l DEPOSITS OF SAND, GRAVEL IN PLACE SAND AND GRAVEL LOCALLY PRESENT :i-l^_ll RIVER FLOODPLAINS AND CHANNELS I SCATTERED DEPOSITS OF SAND AND I GRAVEL *22 ^°^^'^'°^ *'^D NUMBER OF SAMPLE 20 MILES Fig. 4.— Sand and gravel deposits in the Kankakee area. KANKAKEE AREA 31 The location and size of many individ- ual sand dunes is sliown on the topo- jrraphic maps of the Watseka, Momence, Kankakee, Herscher/"' Wilmington, and Morris^^ quadranoles. As the topography of some of the glacial hills of silt and clay (till) is similar to that of the sand dunes, the dune areas may be different- iated on the topographic maps by com- paring the maps with figure 4, or with the Soil Survey maps of Iroquois, Kan- kakee, Will, and Grundy counties.^" Thickness. — Dunes 15 to 25 feet are abundant and some dunes are 25 to 50 feet high. The dune sand is probably about as thick as the dunes are high, except that in the ridges of continuous dunes it may extend below the immedi- ate base of the dunes. As the surface of the underlying water-laid sand is irregu- lar the present topography is not an ac- curate guide to the thickness of the sand. However, over entire areas a mile square or larger the dune sand probably aver- ages 10 feet or more thick. Overburden. — The dune sand com- monly has an overburden of 1 to 2 feet of soil and dark brownish-gray silty sand. Below this zone the upper 2 to 5 feet of sand is generally darker colored and slightly more clayey than that be- low, and part of this zone might also be removed as overburden if desirable to reduce the iron oxide content of the sand. Many of the dunes in this area are or have been forested, and roots are abundant in the upper few feet of these dunes. Grain size. — In general the dune sands reflect grain-size variations of the underlying outwash deposits. In the southern part of the area near Watseka, where the outwash deposits were origi- nally laid down in relatively quiet waters and are fine-grained, the dunes are mostly composed of finer-grained sand than they are a little farther north, near Hopkins Park. The Hopkins Park dune sand is in turn mostly finer- ^^ Athy, L. F., Geology and mineral resources of the Herschei- quadrangle: Illinois Geol. Survey Bull. .55, 1928. ^® Culver, H. E., Geology and mineral resources of the Morris quadrangle: Illinois Geol. Survey Bull. 43B (extract from Bull. 43), 1922. ^' Obtainable from the University of Illinois, Agri- culturn^l Experiment Station, Urbana, Illinois. grained than the sand in the dunes along the main course of Kankakee Valley from Momence to Morris. In the Wat- seka area four samples of dune sand (14-17, tables 1, 2) are relatively fine- grained containing only about 2 per cent coarser than 48-mesli. Three samples (18-20) from the Hopkins Park area contain 5 to 20 per cent coarser than 48-mesh. Four samples (21-24) along Kankakee Valley contain 25 to 50 per cent coarser than 48-mesh, although finer-grained sands are known to occur locally in this area. Composition. — In general the finer- grained sands have the highest feldspar content. The seven samples from the Hopkins Park and Watseka areas aver- age 21 per cent feldspar, ranging from 18 to 24 per cent. The coarser-grained samples from Momence to Morris aver- age 17 per cent feldspar, ranging from 15 to 19 per cent. Chemical analyses of several samples from this area are given in table 5 (p. 17), and are discussed on page 19. Most of the sand exposed is noncal- careous but locally a little slightly cal- careous sand is found near the base of the dunes. As the lower parts of the sand dunes are rarely exposed the occur- rence of calcareous sand may be com- mon. However, at least the upper 10 to 15 feet of many sand dunes is noncal- careous, and locally as much as 35 feet of noncalcareous sand was observed. Size of deposits. — The quantity of dune sand in the area is enormous. For example, the dune area south of Mo- mence and east of St. Anne in the south- east part of Kankakee County probably contains more than a billion tons of sand. However, in most of the dune areas many of the dunes are scattered or the deposits are thin so that the quanti- ties available within half a mile of a possible plant site may not be sufficiently large to provide the reserve needed for a large-scale development. Locally, how- ever, the dunes are more concentrated and the reserves are probably adequate. A few of the areas which appear to have large reserves are listed below. (1) Along Chicago, Milwaukee, St. Paul and Pacific R. R. southeast of 32 FELDSPAR IN ILLINOIS SANDS Momence quadrangle-contour fntervaf 10 tlT t*"!"' ?'^ Momence. (Part of the which are approximately one mile square ) ^^'""""'"^ "'^°^" by the land-sections LACON AREA 33 Momenee (fi^". 5), especially in sees. 16, 21, 33, T. 30 N., R. 11 E. (Momence quadran o\ YfJfq^/V^ffK^ '^^d ra ^ y 9- ^^ mV yi V 23 22 69- WHITE: 70] k T 20 N R. 2E. Fig. 12.— Sand and gravel deposits in the Savanna area. 48 FELDSPAR IN ILLINOIS SANDS Many of the deposits listed above are within a mile of Mississippi River. Large deposits of dune sand farther from the railroads occur east of Cor- dova, in sees. 33 and 34, T. 20 N., R. 2 E., and sees. 19, 20, 29, and 30, T. 20 N., R. 3E. OUTWASH SAND AND GRAVEL Large deposits of outwash sand and gravel underlie the terraces. Except where overlain by dune sand they have an overburden of 1 to 2 feet of soil. At the few places where well exposed, these deposits are noncalcareous and they thus differ from the outwash deposits in the areas previously described, which were calcareous except in a thin weathered zone at the top. As only the upper 25 feet was examined, the lower deposits may be calcareous in part. The terrace deposits are generally more than 100 feet thick and in places are as much a^ 200 feet thick. A sample (65) from a gravel pit about three miles southeast of Savanna contains 19 per cent feldspar but the 8- to 270-mesh fraction contains 21 per cent feldspar. Another sample (69) from a gravel pit about two miles southwest of Albany contains about 11 per cent feldspar bvit the 8- to 270-mesh fraction contains 22 per cent feldspar. The outwash sand and gravel is avail- able in large quantities at many places along all the railroads on the terraces. Oquawka Area The Oquawka area (fig. 13) contains large deposits of dune sand overlying glacial outwash deposits of sand and gravel in terraces along Mississippi River. Sand and gravel also occurs in the channel of Mississippi River, as de- scribed elsewhere (p. 50). DUNE SAND Many large areas of dune sand occur on a terrace which extends from six miles north of New Boston in Mercer County to Lomax in Henderson County. Some of the largest deposits of dune sand occur near New Boston and Keiths- burg in Mercer County, and near Mil- roy, Oquawka, and Gladstone in Hen- derson County. The dunes are well shown on the topographic maps of the Keithsburg, Oquawka, Burlington, and Lomax quadrangles. Those in Mercer County are shown on the soil map of that county. Dunes of sand mixed with hills of sandy loess occur on the upland near Mississippi Valley in extreme western Rock Island County especially in sees. 7, 8, 17, and 18, T. 16 N., R. 5 W. As the deposits appear to be predominately silt and their extent is uncertain they are not mapped in figure 13. Thickness and overhurden. — A few of the dunes on the terraces are 50 to 60 feet high and many are 20 to 30 feet high. The dune sand has a thin soil cover only 1 to 2 feet thick and locally the sand is exposed in blow-outs cover- ing several acres. Grain size. — The dunes are similar in grain size to those in the Savanna area. Four samples (72, 73, 75, 76, tables 1, 2) average 34 per cent coarser than 48- mesh and range from 15 to 54 per cent. They contain 1 to 2 per cent of mate- rial finer than 270-mesh. Composition. — The four samples of dune sand average 21 per cent feldspar and range from 18 to 23 per cent, which is essentially the same as in the dunes in the Savanna area and a little higher than in the dunes in other areas. The exposed dune sand is noncalcare- ous. Size of deposits. — The area contains many millions of tons of dune sand. Large deposits occur along Chicago, Burlington, and Quincy Railroad almost continuously between Keithsburg and Oquawka, especially between Milroy and Keithsburg (Keithsburg and Oquawka quadrangles) and also north of Keiths- burg, in sec. 3, T. 13 N., R. 5 W. (Keithsburg quadrangle) ; along Minne- apolis and St. Louis Railroad east of Keithsburg, in sec. 19, T. 13 N., R. 4 W., and sees. 14, 22-24, T. 13 N., R. 5 W. (Keithsburg quadrangle). Many large deposits occur close to Mississippi River, especially at New Boston, Keiths- burg, and Oquawka. Other large de- OQUAWKA AREA 49 2 R.IW. Fig. 13. — Sand and gravel deposits in the Oquawka area. 50 FELDSPAR IN ILLINOIS SANDS posits occur along- the outer edge of the terrace for six miles north of New Boston and along the inner edge of the terrace about four miles south of Glad- stone (Burlington and Lomax quad- rangles). OUTWASH SAND The outwash deposits are well exposed at several places along the edge of the terrace near Mississippi River. The de- posits are generally more than 100 feet thick and are more than 150 feet thick in some places. The upper 25 to 50 feet is above the level of Mississippi River. Except where overlain by dune sand the outwash deposits have only a thin overburden of soil 1 to 2 feet thick. Along' the channels of Edwards and Pope rivers and other streams crossing- the terrace, the outwash deposits are covered by mixed sand and silt alluvium. Where exposed the deposits are mostly medium-grained sand but locally tliey contain a few pebble streaks and more rarely lenses of gravel. The deposits are mostly light gray, nearly white, but in many places the upper 5 to 10 feet is stained light brown with iron oxide. Where overlain by dune sand the de- posits, at least locally, are comparatively free from iron stain. All the outwash sand examined was noncalcareous. A sample (71) representing the upper 25 feet of sand exposed in a pit about two miles north of New Boston contains 23 per cent feldspar, and a sample (74) representing 10 feet of sand at Oquawka contains 22 per cent feldspar. As the outwash deposits are similar in grain size to overlying dune sands and contain about the same amount of feldspar they might not have to be dif- ferentiated in working the deposits. The greater uniformity of grain size of the dune sand may make it preferable. How- ever, the smaller amount of ironstain on the grains may favor the outwash sands. Very large deposits of outwash sand are available along the railroads ex- cept where covered by thick dune sand. A sample (77) of outwash sand from the upland area near Abingdon, an older deposit unrelated to the terrace deposits, is a noncalcareous medium- grained sand containing feldspar. per cent Mississippi, Illinois, Ohio, and Wabash Rivers mississippi river Enormous quantities of sand and gravel occur at many places along Miss- issippi River, the gravel principally along or near the deeper channels of the river and the sand in bars both in the river and along- its shores. Many sand bars are exposed during intervals of low water and their location is shown on various river maps and the more recent topographic maps, especially those of the Keithsburg, Oquawka, Keokuk, Quincy, Barry, Nebo, Hardin, St. Charles, Granite City, Cahokia, Kim- mswick. Crystal City, Renault, Chester, Altenburg, and Thebes quadrangles. To divert the currents into the major chan- nels and maintain a sufficient depth of water for navigation, jetties have been built at many places along the river (many since the above maps were pub- lished). Behind these jetties immense quantities of sand have accumulated, and at favorable locations such deposits would probably be replaced almost as fast as removed. 8and and gravel have been dredged from the river bed at many places for use principally in the building industry. Grain size. — Sand deposits of almost any grain size desired can be found along the river. The grain-size varia- tions of Mississippi River deposits as shown by sieve analyses of 235 samples collected between Davenport, Iowa, and Cairo, Illinois, have been described.^" Medium- and coarse-grained sand is available almost continuously along the river. The fine-grained sands appear to be more abundant south of East St. Louis. Very large bars, of which at least the upper few feet are fine-grained sands, occur along the river west of Valmeyer, near Chester, south of Thebes, and elsewhere along the river. The sands vary in content of material pass- 22 Lu^, Alvin L., Sedimentation in the Mississippi River between Davenport, Iowa, and Cairo, Illinois : Au^stana Lib. Pubs. No. 11, 1927. OTHER AREAS 51 in^ 270-mesli, some of the very fine- grained sands being- especially silty. However, many deposits contain little silt, and 9 of the 13 samples contain less than 1 per cent of material finer than 270-mesli. Composition. — The Mississippi River sands contain more feldspar than sands in the other rivers and average higher than any other type of sand in Illinois (p. 20 and table 2). The 8- to 270- mesh fraction of 13 samples (83-95, tables 1, 2) of Mississippi River sand averaged 25 per cent feldspar, ranging from 16 to 34 per cent. The six sam- ples (90-95) of sand from below East St. Louis contain more feldspar than the samples from np the valley, averag- ing 30 per cent and ranging from 26 to 34 per cent. Although this may be in part attributed to the finer-grain size of the sands south of East St. Louis, it appears to be a general characteristic in- asmuch as a sample of coarse pebbly sand collected near Harrisonville, east of Valmeyer, is 89 per cent coarser than 48-mesh and contains 26 per cent feld- spar (sample 93). The Mississippi River sands are gen- erally slightly calcareous. Two samples (85, 86) are noncalcareous but the re- maining samples average about 2 per cent soluble in acid. Some of the acid- soluble material, perhaps as much as 1 per cent, is probably iron oxide and soluble minerals other than carbonates. The maximum amount soluble was 5 per cent (sample 92). ILLINOIS RIVER Bars of sand and gravel are common along the channel of Illinois River, espe- cially south of Peoria. Partly because of dams there are no large sand flats exposed along Illinois River. Sand and gravel for commercial uses is dredged from the river, especially between Havana and Beardstown. Locally bars of sand occur on the floodplain near the river but these are usually silty and not large. Three samples of sand collected from the edge of the river at Havana, (sam- ple 80, tables 1, 2), Florence (sample 81), and Hardin (sample 82) are not as coarse-grained as much of the sand transported by the river. Omitting the material coarser than 8-mesh and finer than 270-mesli, which is variable, the sample from Havana contains 9 per cent feldspar, that at Florence 10 per cent, and that at Hardin 12 per cent, suggest- ing a slight increase in feldspar content down the valley. OHIO RIVER Large quantities of sand occur in bars along the channel of Ohio River. A sample (98, tables 1, 2) collected from a beach at the north end of Shawnee- town is a noncalcareous sand containing 16 per cent feldspar. Samples from beaches at Rosiclare (99) and at Olm- sted (100) are calcareous sands contain- ing 11 and 6 per cent feldspar. The low feldspar content of these sands may be due to the introduction of Cretace- ous-Tertiary sands which are exposed in the nearby bluffs and contain little feldspar. A sample (101) of calcareous fine-grained sand collected from the river's edge at Cairo contains 21 per cent feldspar. W^ABASH RIVER Wabash River transports large quanti- ties of sand and gravel, and in its lower course many board sand flats are ex- posed along the river at low water. A sample (96, tables 1, 2) of pebbly cal- careous sand from the shore of the river at Hutsonville contains 13 per cent feld- spar, but the 8- to 270-mesh fraction contains 17 per cent feldspar. A sam- ple of calcareous sand from a large bar near Grayville contains 19 per cent feldspar (sample 97). Other Areas In the parts of Illinois not included in the areas described above (fig. 2), sand and gravel deposits are locally present (fig. 1). Most of these deposits occur in the glaciated areas of the State and are outwash deposits similar to the outwash deposits in the areas described. Although some are large they are gen- erally much less extensive than the de- posits in the areas described and there- fore are not individually described in this report. 52 FELDSPAR IN ILLINOIS SANDS Some of the largest sand deposits out- side the map-areas occur near Green- ville and Vandalia in Bond and Fayette counties. These are noncalcareous out- wash deposits of pebbly sand mostly stained dark brown with limonite. A sample (78, tables 1, 2) from near Greenville contains 12 per cent feldspar. Because of the relatively high feld- spar content of the Mississippi River sands south of East St. Louis, dunes of comparable feldspar content might be expected to occur along the east bluffs of the valley and the adjacent upland areas. In this area, however, there are no laro^e terraces alono- the bluffs as there are where sand dunes occur far- ther north, and the floodplain of the river occupies the entire bottomland of the valley. Because of the siltiness of the sands deposited on the floodplains, repeated flooding, and generally moist conditions of the floodplains, no exten- sive deposits of wind-blown sand have been formed. West of Anna wind-blown sand appears to fill a tributary ravine near the bluffs. The quantity of sand available is uncertain but there may be large quantities in scattered deposits of this character. A sample (79) from the deposit west of Anna is a noncalcareous fine-grained sand and contains 29 per cent feldspar. DESCRIPTION OF SAMPLES 53 -^1 ^ ^ ■+-) 03 :3 o ^^ ^ §^ o « £ 6 "Ota P^'^''^ OJ o •S.S o o s 13 :3 ;3-c :3 :3 j- ^^ I I I 1 O I I o o .^ rt^ "^ rt^ ^^ iT^ /^ n~i Q;j o o^ o'S o.t^ o > >.-S.t^ -^ 02 over- burdei ft. c ness 5ampled \c^ \C0\1M X,C^ OC^r-' CO ^ lO CO CO "^ «0 CO o COt^ >^ Xi C C C d C C CJ2 c3 03^ jO o3^^rt^^^o3o3o3o3o3^KJ^ «3 (MfMCOiOiOTt^Tt^TtiC^iO WW 05 Oi ;z;;z;^^^^Z^:z:;z; :z;;z^ "^ ^^^^:z;^^^;z;;z;^^^!z: COCOC^COcOcOcOcOcOiO TtHrtHTttCOeOCOCOCO-*-^ COCOCOt^OOOO^^tMCOCOTtHCO (N5^COCOCN(NCN^CO ::^ ^ II "^T^m^^^mmmmmmmT^Z, ::^ mm 00 CO CO CO CO oi oj ^ ^ -i.>-. ^ c c >> T3 0) s6i|f|ll6| CCT3 lillillill 3.0 o3o3o3o3S'»'»«^2 feC-^-*^'^ tct»MwO-^^c^c ,dS< -^-^03030000 -^ '^ S3CS3 00hJHHJc5ffi O^tf ssggQffiaa^gaaai ^ (M CO "^ 10 CO b- QO OS O ■ '^kOCOt^OCOO— i(MC0^iOcOt>. 54 FELDSPAR IN ILLINOIS SANDS T- '^ ^ O -M CO 1^ -^^ V ^ 3 V ^ 03 ^ d ?^ 53 CU 03 PL, Ph C^ P^ o 05 CO 03 O TO O > ' O ' ■ • • • _^ g T3 ^ -rJ -rs -r; T3 -^ >j +J -U +i -tJ u a u u o , ^ , 03 03 '.■t^o3a;Oo300000 Oh PJ CQ 0^ pj tf tf tf p:^ pj o3 bC O S 05 iOiOOOCOt^OOOiO'-CO ;j; ^ (M (M ^ C8 ^:z;:z;:z;^ :z;:z; ;z; :z; :?; ^ ;z; ^ :z; ^ :z; ^ Z ^ ^ iz;:^^^ »o to (>1 CO t^ c^ cocoes — ^ s > (M CO CDfMXOOCCMiOCOOOCXOOO (M 00 lOOi ill ::^ :z; ^Zxx^^^;^x:z;^;z; ^xlz;!?; 1 \^ mil > ^ p. M W M M ^ w ^ > w xZxx:^xx;z;Z;z;^;z; :^ X ^ X X :^ ^ X X X :^ X :^ xx:^:^ s s s Qi G fi C S £- Sm +J +J ^J Q Q 3 3 :3 3 CI>>CCCCCC 03 r: o r, :f^ o o o o o o bc |i||iisa§3is 000 bC bC bC ^ ^ o3 a a oj SSS5 C C ;h ^H ;::3 ^ n OJ a; OJ j= ^ o o 'S'S 03 03 03^ c i=: ce o3 .t^ o c c b o o 032 ^^^ o u pQ u ;^ O^XO^PQ a; X -^ lO CO l:^ 00 Oi O -^ . COCO CO CO CO CO '^ Tt^ -^ "^ Tti ■* '^ Tt* 00O5 o T-i Tj^ rfi 10 10 DESCRIPTION OF SAMPLES 55 =5^3:3^:3^:33:3 3 3 33 3 33a='=3o, q:;^ CCCOOWOC U OOO OOqOOq CC o'oOol3o'a3qqq.-t^q q.-S.t^-2^.-S^ .-Sqq3003 ."S.-S csSsS (X) r-* (M iM iX) ^ (M t^ ^ r^ »0 ^ CO to C<> CO O TtH> Tt^ CO O CO rfi t^ (M ^ lO 00 lO CO to O O O CO 73 t; -a TS-o C Cl C 3 3 ^ 03 03 cj 1^ 02 03 CO CO SC T3 T3 t3 -C -O T3 -a -13 -O -C > "TS -^3 -Q TS 73 XS > TJ ^ -Q "73 -CO 73 t3 J2 t3 -2 _2 > x-s C3333C33G3033 3^333^33 Xi a G G G C G J=i G -DJ2?3 © c8c3o3o3o3o3<73!:3o3o3^'So3 (:3 lO to t)h lO to to ti CO CO CO CO CO (M 1> Oi O — ' ^ to Tfi Ttt (M ^ ^ O {8 Tt* CO 3 -0-^333^10"^^ ^^^ M3«^=3'3C ==2 -- S S S13 o g g g:^ 2 2 o >>>33££ l-Z^^^%-Z S§ ^^^ ^<<;^^^<;<; OOCl Or-^fM lOtOiOtOtOiOtOtOCOcOcOcO -^cococococot^ l>l^i>.I>.I>t>t^ t>.t^ 000000 56 FELDSPAR IN ILLINOIS SANDS CO 03 S o3o3o3c«c3c3aJo3JHo3a;cSo3 r^rorornrornOrornroPirnrn Beach Bar on floodplain Beach Beach Road-cut Pit Pit Pit Outcrop along stream 1 ness over- burden ft. + Tti CO »OCO iO 1 (M ^ t-H CO Thick- ness sampled ft. oocioo Material c c c c c 03 03 03 03 03 CO 02 CO y. CO >. >. >. >. >. T3 II Sand Sand Pebbly sand Sand H H H H H 1 ^ c & s > C0(M0CCCCOCO — — — t^co si} wwww www^i^ C (X C^J t^ „ CS TtH Tfl CO ^ Town- ship Pi •1 s 00 CO fa © OJCOiOt^ 2 CO Tfi Tt^ lO 00 -^-^-H ^ COCOCO -H ■B 03 OiCOCCOTt'-ti'^ GOXOOCOQC 1 2 o OiiOOO »o 1-H 05 05 O CO CO ^co :^ Wt^C^W mmmm Wk:k:^^ :^ WW :z;:z; WWWaw :^ ww^ Carroll Rock Island Hancock Pike Madison Madison Madison St. Clair Monroe Monroe Monroe Randolph Alexander l1 g 03 Gallatin Hardin Pulaski Alexander Cook LaSalle LaSalle Bond Cass 1 Savanna Rock Island Hamilton Louisiana Alton Alton Alton East Carondelet Harrisonville Harrisonville Harrisonville Chester Thebes Shawneetown Rosiclare Olmsted Cairo loHet Wedron Wedron Greenville Virginia 0) 0000Q000000000OlO5OiOiO5Oi ^fe 00 OiC -H O: OiOO §§222 SIEVE AND MINERAL ANALYSES— EXPLANATION 57 Table 2. — Sieve and Mineral Analyses — Explanation Condition* A. — Sieve analysis of the part of the sample finer than 8-mesh in its natural condition. Percentage finer than 270- mesh determined by washing on 270- mesh sieve. B. — Sieve analysis of the sample tested under A (excluding the — 270-mesh fraction) after removing the carbonates and iron oxides by digesting in acid (HCl). Determined only for the cal- careous samples. C. — The percentage of each sieve-size soluble in acid is determined from the loss of weight of the material retained on each sieve-size after the acid treat- ment and resieving. In a few samples some aggregates in the coarser sieve- sizes break down during the acid treat- ment causing the finer fractions to show an increase after the acid treatment. Gains are marked +. Determined only for the calcareous samples. D. — The mineral analyses of the cal- careous samples were made of the sieve- fractions after the acid treatment and sieving (condition B), thus removing the carbonates and iron oxides. Of the noncalcareous sands only the individual sieve-sizes studied were acid treated, re- moving the iron oxides. Probably small amounts of other minerals were also dis- solved from both types of samples. E. — The mineral analysis of the — 8 -f-270-mesh fraction of the samples, after acid treatment, is calculated from the mineral analyses of the individual sieve-fractions recorded under D com- bined with estimates of the composition of the remaining sieve-sizes represented in the sample. These estimates were based on the probable gradation between the sieve-sizes analyzed and on the anal- yses of other samples which show the general trend of the variations in min- * A detailed description of the procedure followed in making these tests is given on pages 9-11. eral composition. Each sieve-size was weighted according to its amount as re- corded under condition B. Reported only for the calcareous samples. F. — The mineral analysis of the — 8 +270 fraction of the calcareous samples in their natural condition is calculated fiom E by adding to the "others" the total amount acid-soluble — the carbon- ates and iron oxides — given under C, and proportionately reducing the amount of each mineral shown under E. As the noncalcareous samples contain only a small amount of acid-soluble ma- terial (rarely more than 2 per cent) this amount would not materially change the analyses and therefore the amount acid-soluble was generally not determined. The analysis is calculated directly from the analyses recorded un- der D with estimates of the composition of the intervening sieve-sizes as described under condition E. G. — The total feldspar, acid-treated, is the sum of the potash and soda-lime feldspars in the mineral analysis above, under condition D. The total feldspar, natural, is the percentage of feldspar when the acid soluble minerals are in- cluded. It is calculated from the total feldspar, acid-treated, by taking into account the percentage of the acid-solu- ble material for each sieve-size given under condition C. H. — The total feldspar in the sample, as sampled, is determined by reducing the total feldspar in the — 8 +270-mesh fraction given under condition F by the amount which the inclusion of the +8- mesh and the — 270-mesh fractions re- quires. It assumes that there is no feld- spar in the +8-mesh and — 270-mesh fractions. A small percentage of feld- spar is no doubt present in these frac- tions but it is smaller than in the re- mainder of the sample and may not be recoverable commercially. 58 FELDSPAR IN ILLINOIS SANDS w a -a ^ O »^00C0C0i-H(Mr^^'**H >OCOCOiOOiQOOOiOOOOOO CO T3 OSOOC*5eOOt^--^CD CDTt-a5»OCOCOCNOOOOi Ort^OOOiOOOOOOOOO — 1-H -H C^ (M C^ -ff I H 5^ 1 t^ 1 (M ^ t^ ,— ^ ' + t^COOiCO _|_(M CD CM WX!"^ 1 •SvS < 1 -o 8 t^ iO 00 (M CD (N CO(N OJ (£) ,—1 cd iC Q-£3 CO (M CO 0: CO _|__l_CO 00 1 1 CM ^ -o 00 00 (M ^^^ + 00 -c^-^ 1 c << (M --H CO I CO ^ t^ r^ ^ [^ cot>- c 10 CM ^ re u O »00 r^ Ca r-^ 1^ 1 ^ 05 !-» ,-1 r-H T^ (M ^ o t. 10 r- 1 I> 00 (M ^ _1_ ^ 1 to Tfl 00 I^ ^ l-H « CD J3 qs E z 00 10 CD Oi 10 -rfl _|_r^ iO Tfl 1 . < Tt^ ,—1 r-H 10 Tti CD CO "^ CO CD Tfi SI CO |> ^ 1 r-l ,-1 --H t> CN Tfl Oi I> OiTtH «N CO (M -H ^ CM CM c TjH 0) Tt< 00 Tfl CN r^ Oi CD CD CM O (M (M CO CM CM 9i ^ <: c i=r (0 .0 S^ -" Uy (-1 03 -C re c < re 6 CO OJ 05 211 s oil-. Elf iff 4) C i Co * J" c r ■ SIEVE AND MINERAL ANALYSES 59 O c tB-C • Oi 00 lO _L_|_'-H t>- 00 eooiOcO'-H _|_^ Oi Ol 1 1 1 c^ -3 g COCO^^^^-^ O .^ -H i^ (M 1 2 1 gS2^+++ 1 S lo 1 ioai05Tt^(NO-H CO 1 t- 00 CO ^ 1 ' 1 CO t> Ci CO ^ ^ CO CD 2 o o i. 9) SI E < 1 cooC — Tt. -^'-^(mI 'c: 1> ^ ^ 3 z o o (M 00 ^ -r O 00 c a; O s COI> C -* T-H _|_C^ t^ »o s- 4) 0^ (0 4) W re < "re t. - -d COiO .c. i-HCOtMOCOCOt^COOOOOOi 4) 35 -S"^ T-^ .-H ^ ^ r-H ^ 05 ^ <1J J3 1 '*OOTtiiOiOiOa3rtit^l>COOOO 0) O OOt^COrtHr-HOTjHC^OOOiOOi l> lO CO >0 t!H lO lO J3 3 :O»OTftC0C ^ >» TtOOrt^OOOTjHcOCO ••-• ^^0 re S fl «*- o o >3 M ^ d 5 re c < r*^ O'*O00i000i0OOOOO'-3 t» 1— ii-HCOiNCO-^COO^Ot^b- « S 1 ^^(^^cqc;^-g <» :^ 1 1h F Natural (est.) CO + T CO to E Acid treated (est.) o CO + 00 1 1 CO D Acid treated ^ coTt^ Oio -^ oco '^^ F Natural (est.) o + 00 1 CO Tt^ COrH Tt^ ICO t>. rt^ E Acid treated (est.) o + T CDCOt^Tj^ iO_LC0 CO CO D Acid treated 00 05 CO t>- l> fH O _L CO ^ + coo CO CO 00 CO CO CO Oi CO lO O Tt^ CO ^ CO ^ s^^ F Natural (est.) CO + 00 1 tH CO 00 CO _l_r^ CO CO S -d qI < g UOCO OCO 4_T-H rH 1—1 CO (0 8 lO^t^C^ +4-*^ 1— 1 CO "re S- O >♦- o t. 0) E 3 CO Oi CO CO 00 CO _1_C0 Tt^ ^ CO 1 00 F Natural (est.) + O CO -^ "^ F-i ICO 1> T— 1 T— t 1^ ?5 CO CO z D Acid treated o 1—1 CO Th Or-H 1 ^CO CO C O 8 1— ( OCOCO CO T-H 1 CO CO w . re c < re 0) E i I % 1 Quartz Potash feldspar Soda-lime feldspar Shale, etc. Chert Heavy minerals Others Condition G" Total feldspar: Acid treated Natural Condition H" Total feldspar as sampled SIEVE AND MINERAL ANALYSES 61 (MOOcO(N»OiOOOTt^O X O) ■«-• c 0) O 4) b^b^ CO (M (M o 1 CO (N O lO O Oi t^ t^ l> t^ t^ to Tt< TJH lO CO 00 lO 0) E re DC COOSOOOOOO'itiCt^COCOCOCO ^(N^i005Tt 3^ ^1 t^ 02 »0 to iO Ot^ t^ O O O TtH t^cOcOcOcOcOtOiCiOiOt^ CO tOt^iOCOcOr-^(Ml>cOCO'*"<^cO 00 c (0 1- COrt^h-obOcOcO-HOOOOO c 1 03 CO(M(Nb-iOCOOiTttTt^TtHiOOOO il .5 lOiOt^OSIXN^rHOOOtOOJ ^ CI (M 05 (0 IE •»- o (0 4) M re c < > 1 c o O CO O'*O00»C00iCOOOOO--3 T^i-i(M s^ F Natural (est.) o + T ^ Q. V) 1 re E < re « E i o o O Quartz Potash feldspar Soda-lime feldspar Shale, etc. Chert Heavy minerals Others Condition G" Total feldspar Acid treated Natural Condition Hi* Total feldspar as sampled ^s 62 FELDSPAR IN ILLINOIS SANDS 35 C O C ^ 00 o 0) CO t:; .^ o c e ^- ^ art f*^ ^ ,. o 15 1 C^OO«-'-^'-"00eoo ^oocor;^c^;5C3t^oog .1 1 1 c o O Ort^OQOiOOOiOOOOOO--; 1 o 1 CO;^^(M+^.^ 1 a i> 1 (M 15^ 1 X t^ CO . ^^ ^H 1 ^ '=5^-^ t^ (M t- . 1 o re CM t- O o CO -- — -H ICO ^ t^ r-l ^ ^ C^J o -g^ ^ (M «> Si E ^P + 00 :z;^ 1 3 z 1 o 050 Oi^ O-H _|_ t^^ -t- 05 >» TS o '"' Si oil 1 ^ 1 c < 2i lO co t^ t^ C-) o o ^ Tt^ 4) -►J 1 ^ 00 "-^ o o Oi t- a> Q. ^ c 1 -3 QJ .1 s ^-2 (8 E < o O dspa feldi nera ^2 S S dition H^ otal feldsp as sample re s- 0) E Quartz Potash fel Soda-lime Shale, etc, Chert Heavy mi Others dition otal k Acid Natu r SIEVE AND MINERAL ANALYSES 63 0) O) =^ S o ? , , S o c 4) O* o i^ d C O 0) tz/ TJ SI •M c 0) o L. 4) Q. <5 (MOC^QOCO(MC^O^OO CO CO r-l O ,-iCOCOi:OCOO(MO(N (1:^000500000^^0(^0 H CO CO r-H o TtC^0i'-H (MQOTjHTt^OClMOTt* O o O-^OOOiOOOiOOOOOO'— ^-"HC^JC^JcO-^OOtOOt^t^ os --1 ^ (M 03 O: 05 CO 1 ^ ^ 00 -S "S ^ ^ 00 05 lo i>. r^ ^ o '^ (M Qi: TfH t^ T3 s <1 00 O CO 05 o Ol lO (M -H lO o 00 O 05 --I -Lr^ ^ Oi 03^ i>- r— 1 tH ^:- (M &^5^ + 'SvS' 00 ^ ^ ^ COiOOOCOiM 00 n-* o O-H^ (M ^ T3 .< 00 (M t^ t^ CO ^ O _L 00 I Tt^ o; o is -3 S 03 ^y. ;-< c Jrt ^ - ^-2 o3xS o ?^-C 03 ^^ ^ a cu O 2 II i 61 i^ K2| ITk^-^n ^2a ^ -S-rt^ »'-Hr-^,-HT^ (M o3 D<^^ ^g -73 i^cD(M«oocort^cb-cO'-taor- X o^Ttr^otJt^ocooccooi O) 73 OJ 1 ^(N(Mr^ 05 0> 33 o-g ^ ^ 2^ 1 >% Si c "Is ^Tj^CSiO^^O(N<©(M^CO-^ o ^(MiOOiOiOOSiOCCC — O <15 r^COC^J O Q. ^ a; ^ O00(M »OIOCO(M --^ O C CO -C a; 00 t>. t^ t>- !>• t^ t>- t^ !>• t^ t^ O _Q o ^J<^ tJ ^i <) < 1 CDTt*OieOiC<£>iOCt^t--Tt^TtHO c -TS 1 t^05(MCC-H»OTj^C^000005 n 73 % O rt c < 0) c 1 Ot!^ OGOiOODiC C O OOO — > ^r^CatNCO-^cDOOOt^t^w 0) o ^^cq^a(N^ to S 1 1h e O iC Oi CO iC _|_iC T^ <^^-^ (M -_ 3 -fj + ^^^i °f :^'^ 1 'i O r^ CO c^ 00 CD _|_^ 00 5^ (N ^-1 + -O^ ' O oo 00 lO c c^ _]_ 'O o qll y—> CO ''I ss iO lO (0 E "re o CO CSOiTjH 1 ^ ^ 00 1- Oj t^ .—1 O 2-^ (N «^ '^5^ + o =^-3 00 L. Iz; 4) £ 3 -^ 8 t^ 00(M -f--|-^ o z 73 s t^O.G.^+ + - 00 c 0) O < 1 ^ 1 r^ - »o 00 t- 1 4) a O ^ ?. CO re c < "re t- 0) 6 ^ as 2 211 1 ^ O 0_fl -^ ^ -*^ E i r SIEVE AND MINERAL ANALYSES 65 03 T. e ^ oc o o) 02 t; ex a; ?^ "o c % Acid soluble ^ — ( COb- CT>iO"^0000^^05C^«^»00 C 0) O &. 4) n CO^t-cDfNCOO^t^OOOCOC -^ (N (N O 3 O (0 ;d "o < 3^ ^1 t>. CO (M 00 I:^ 00 lO CO '-^ ^^COr^-H,^(M^ CO c 3 O Tt^t>.^l>^iOt-iOrtHiOC^00O E < -a c re ■o (NOOCO(M(MCOOOOOO — Oi '^(MCO-^rt^OOCOTt^COiMC^Xt- E "re 0) t^-HiO0005(MOOOOOC0Oi (N (M r^ -H Oi s: ^»C(MOi®05005iCiO>OI> E O fc-OO» re E < V > o Or^OOOiOOOiOCOOOO--; T-ir-cqc^icO'^coO'OOt^r'"^ 1 H , o C: Tti 0«2-^ _|_t^ 1 ■^ 23,— V r^ 1 t4 '^ (M 1 ^-S 4- c3^ 1 00 ^ 1 1 1 -^ 1 o 05 lO (M t^ Tti ICO 1 t^ r- ^- ^ 1 00 -o^ a ^ 1 « lO lO (N CO -^ O ^ 1 t^cc -rs Tt* l> ^ 1 T3 a; =•15 < £ 00 i>ioc^t^o ceo t^iO ^ (M CO ^ o 2-7 (M 0 CO iO iO CO O CO 00 CO t- o ^ ^ 1> Oix X CO ^ r^ _l_ CO c^5^ + .S^ op ^ o Oi r-H t^ (M 1 ^ 1 00 T3 OJ 1— 1 -^ c 03 ^ S 00 * Q CO t^ t^ CO o o o Tt^ CO A •«-• - 1 00 1 c a> on 1 OOOCOCOCOOO Tt" ^ c^ O T*H 1 1^ '~* u Q. -o 1 (0 o ij S 1 4) (0 -5 S !3 ^ -^ i^'^ ^s 03 T3 re E < re t- 4> r a i r he- 88 hh 66 FELDSPAR IN ILLINOIS SANDS CO e O CD CC Tj t^ o c eo -T3 1 00(M COOCO-H tH C O C < 73 03 1 cocoicoicccooOr-icocO'-icot* COt^^OOO-- — 05CDOOOOC5 ^ CO ^ o A Natural tocO(rooO'^(MTfTfiocO'-Hi>Oi C5COOOOCOOCDiOCCO--Oi r-1 ^ (M ^ o: A Natural (MCCeO0^(M'^C; O^(NC0cD^(Mi0'-^^O(r0C 1 COCOC-l---^ — — CO — -73 < r-iOCOGC fcH u, (-oO'-iiOtOeOcOcDC505 id C o U ^ S ^ T-iT-i(M(>JC0'*cDC>OCl:^t^_3 E ^ o Natural (est.) + op lO to !>. CO -^ 1 CO T— 1 o E Acid treated (est.) + op OOCO 0:X»0 .j.'* iO Acid treated § Oil> 00 lO .[..Lt-h iOtJh 00 OOiOt^t^(MO — (M O Natural (est.) T iOt^ c »o — -^ -H t^ r-H r- CO ! 8 g::2+^°^+ 1 ^ 1 GO r^t^ Oi ic r^ c — CO ^ XiO00CD CO t^ -^ C CO CO ^ 05 F Natural (est.) o + T rf OC 00 CO 1 — CO CO T^ r^ CO lO E Acid treated (est.) + 00 1 IOC OCO _!_-- — ' t^ ,-H r-l ^ o D Acid treated ^ 1 1 § ■"f o o: »o — _l_ — 05I> Condition:'" _. Ja S ^ Quartz Potash feldspar Soda-lime feldspar Shale, etc. Chert Heavy minerals Others Condition G'- Total feldspar Acid treated Natural Condition H'- Total feldspar as sampled SIEVE AND MINERAL ANALYSES 67 1) o c % Acid Soluble t^t^0000(NO00 Oi B Acid Treated ^(NOioot^eCTt^cOTt^T-MiMt^ ooo»c^iOOeo^oooi eoeciN Oi i-HC^^Oi-HiCOOOOOCMOOC^ oo-o-*o^-oog 2 r-(COOiOi'*(MOI>cOOO(M ^OO(N00Ttr-i(MiOOC0O A Natural ^^O-HC0Tt^(©OC^i0C^00 ^oo-HTHt>,coou:>(MOicoi C % Acid Soluble 1>00 00 CO 1> Tti !>. Oi Oi -H ^ ^ ^ T-H (M B Acid Treated 1— iCOCOCO^O'-HCX)«Di— i(NCi 1 '-H^coTtii:D05t^coot^^cooo OOO'-HCOCXDcOiOCMOO-HOi ^ Tfl C^ Oi Condition:'- Mesh r-H r-1 (M CM (M -g 1 Eh o Oi r^ 05 -^ I ^ o CD ' i-H CD c3 t^ S'^ ^ ^5"^ 4- '^■3 00 'z ^^ g t^ ^ i^ 00 W-TSt^ + •o3 00 < 1 T3 8 1 ^ OO^CO _|_CO r-H t- ^ T^ 05t^ 1 i-H 73 § 00 00 00-* + + <^ CD iO o 1 ^ + 1 1 05 fc^-g-s + =^3 It o 05 "*• (N _L.O CO CM CD lO CM T— 1 '^ "§ § l> 05 --H CM O ^ 1 R 0^ ^ ^ O2 00 05CM -|--(-CM r^ I> CO _1_0 ^ 00 + "* , o So J^ 05 05I>.CM 1 CM ^ CD ;^5^ + =«vS 00 Iz; CD o I-, ^ OOOCM _|_ _l o CM 03 Q^ lO r-^ Oi lO CM ^ ^ r-H "* «:> 00 73 a <1 00 ■^ t^ iO CO _1_0 '-H 00 T^ CM lO o o3 ^-^ t>- CM t^t^CO -H _|_0 Th CM ^ 5 "1 + ^^ 00 Iz; 1 73 o OlOOOOCO-H 1^ CD "S^ (N w^^ + 00 73 ^-^ 1 a <| -^1 ^ t.^ooc^_|_-- OiX o ^51 00 O: ■«* 05 to CM C -H CO — -* Ttl t^ 1—1 ,— 1 '"" C o CO (D - -5 S 3 ^ u.'^ c ^ ^ 03 73 6 6 ill ^ O o JS-^ '^ -t^ o o H 68 FELDSPAR IN ILLINOIS SANDS c. ^ T^ g lO Oi 00 00 rt^ -|--|-'-^ I CO 05 CO _j_o < p -a .^ .^ +J -4 c c3 < a; t>. O O^ - Acid treated s Tt ^ (N - C (N _|_ CO § 00 00 05 Tf 11^ t^; ^ -^ Tj^ ^ o -^ 00 CO CO 00 »0 t^ t>. M >. re c < > c c OTfOOOUDOOJOOOOOO-- i-H^(M(MCO'*COOiOOt^t^ ^ 1 H ot^xco+-^ IC , 1 t^ ^^ (M T -q 8 OXGC-+C.- CO -t-9 °8 (M lOOC^ _|_0 ^ 00 1 CO IC ^ ^ OS CO (M _I_'-' <-- 00 1^ |C s- s -^^ r. iO i-H -I-'-' T*- 2-^ ^H^tg + <^3 00 ^ 1 Ttl 1 00 C5 X CO _L.^ ^ t^ 00 -^ COCOiO-H c — (M T^i 00 ^ '^^^ 00 fe5^ + ««3 00 ^ 1 -c 10 — 1 (M _|_ — -^ „ 4) (M -»J cS q5 § 10 :5 00 CO 00 X CO (M C _|_ CO t^ t" 1- OCcC--_f_-HC^ CO f^-s + hS-^ 00 u ^ 1 ^ E 3 x: (M CO C5 4-0 >o ^ (N 7 (U iC 73 .sl si 70 FELDSPAR IN ILLINOIS SANDS „ o O (U OQ ^ OOrfcOOI>OXO 05 CO CO (M ^ ^ ^ '— 1 (M ■* r^ 3^ '5 2 :;<:^ ^1 ^ ■«-• O) -^ (MiO)MO5(Nai(MCD'*(M^Tf00 t^t-OOiOC^'^'osCOOOOOOi tt) -3 ^ r^ 'M (M O: ^ III'S'S >% ^ ^1 •»-• c 0) O 'e5 C0i-r>t>^ ^1 X ."^ O) ^ '« ^ >* ^ ■«-• E a> O t- (U Q. ^-^ X (0 1 — lOTt-oaoocOr^io^oooo 0) , O ns E < 0) 43 OrhOOOiOOOiOOOOOO-- > 02 .— (T-((M(NCOTtH!riO»OOt^l> 53 a> OJ -H^(N(N(N -g W S o "* CO C35 Tf Ot) 1 ^ (M l> ^_ (M 2- + '■^-1 00 03^ "S o t>. Tt^ r^ iO r^ _J_CS| c© ,-H ^ T^ lO -2 t- CJ,^ c^ ^-1 + -^^ o ^ 1 00 1 ^^Q0rt.^+^ c^ c rf -^3 -O 4J ^'^ s^ < 2i 00 OJTt^ (M t^t^ C — 0-* -tJ (M t- o COCOt^(M •* _[_Q0 CO , t^ 1—1 + "^^^ ^ 'Z ' -^ o l>t>O0C^ lO _|_^ lO 03.-. ^c^ '^-1 + -d^ 00 o 1 < 00 C0I>CO -hC^I _|_-h CO — Tt< r— 1 r-J -3 -a a^ ^■^i << 2S 00 lO rtH Oi t^ CO O (M CO — -kJ (N CO ^ (M o §^^^++^ 00 n- '^^^ + ^•3 00 z 1 „«l^ E ns I- 8 5^-^++^ + 00 o 1*- 0) o 2 o^^^+o-- 00 SI 03 h qS 3 z 00 .-1 CO CO ^ _|_0 (M CO >» < Si 4-> E 4) lO o CO CO ^ c^ o ^ CO CO Oi o 00 1. a> Q. o X s i ^ 03 53- -2 s? n E < s. - GO illllll oil-. -^ c3 O^ T3 O "^ SIEVE AND MINERAL ANALYSES 71 S ^ GO O « X "3 1 <5 ^Tj^cOQOTt^Tj^COTfiMTt^O doco:do5oot>^c^'o— 'O ^4^ 33 -:^irO O X z OJ '« ^ x SI ■M c v o t. V Q. >— ' _^ j> 3S < 5 — (Tj^xaoosxxt — ^oo SI odioixMi>.?oodoc; 3 03 c <-2 ..^TjHio-Xi'NC^O-Xi^TtTt c •-I re r^ C^ Tf Oi a: ••-• X ro "« ^ >» ^ t^i>-,cc;C;c;-tt^ro — c; as _ lOcorccc-M ^rcic->c — •M £ '"^ "^ o 0< 3 t_ ^1 V ^ X 'MCO--Crf — XOutJCliOrC^O (0 ooo-N — c^ib-aico — ocJo s -a a; — !^^c^— o 00 t-totorrc; L. 1 V oooc^ioc-iioxTfc^ic; — 05 c il 53 1 _ z re Z. 0) ■M re ^ S _o H- o ."i (0 ^ 4> ~ U) >» o re E < 9i ^ I 0'*'OX>OM»oooooc;--3 > "m ^^(MC^lCOrfCOOiOOt^t^ 33 V aj -- — |(N 'N (M -g 1 1 ^ (0 S i? ii 51 M I ^ I I I I x»o X + D Acid treated § §-'"- =++ t^ § §■"*-+++ C-. O I X q5 lO l^ lO Tf 'M r- CO X ^3 t^ I X + ! + + < li ^2-=--- 1 ^ 5:--^"+ + + + at 1 X 1 ^ o^u':^,^,o + - O I OiOiC'M — — O + 1 Ca CO CO CO ^ --1 .— 1 CN I 1 + 1 I ' I < 1 D Acid treated § —I X X '- _|_ , X 1 ' coco X Ort..-CO+-- Clt^ ^u -tJ-3 c3 fcH > c; OJ o3^ O'Cux^OKO ! o si > a; "5- 5 •— 33 — ^ ^ 33 72 FELDSPAR IN ILLINOIS SANDS t^ c o c ^ coco(Ni>coooeo(Meo(NcOiC rIOO(NO05C005»OTjHi-<(M05 CQ"5 lo S ® i^ ^CO"<*<(M'^:OCC'Q0(NC0' '-'*(MO«0 H -H coco '-' Oi o-^oooioocoooooo — I H o Oi CO Oi C^J (M r-l ^ 1 IC t^ l> 1 ,—1 , 1 (N 2- + 'x.5^ op 1- 1 1 00 05 ■* O C 00 ^ CO ^ CO —I 1 - -< ^ ^ (0 c o 1 t^ CO 10 CO (>i CO _^ --^ ^ 2 03 ^-v 1 (M 1 + 1 1 o •*- ^-1 o ^ 1 t- a> ^ £ 3 1 (M "^ CO _1_C _1_^ 05 ^ ^ 1 l> z >* ^ 00 1 10 CO CO (M -^ _|_ 1 CO -H ^ ^ '^ t- 1 1 (U 1 n ^ C is (0 4) >, m c c o O 0) 1^ 1 ii -1 < 'T3'*-' . c _ aj C 2 ?* sis c i SIEVE AND MINERAL ANALYSES 73 ^ S o c o 5^ 5 oi s - s c-"z C C X -c 03 » ^ •«-• C 0) o s. a> Q. ■«-• o ^ 3 O c3 (0 <-2 OC^OXXOOfNX "O 1-— iCOClX'OrfC^Oi ^ — .C c d -Hi^OXCOXX'^CO-- «5 0) <5 HH^^S^^iJ^S^-^^i tc 03 ■M £ O) (U ^ >s ^ ^^^^-^g?g 2 ■M -O OJ c 93 O o^-i t- ES^ « Q. X ■T3 r^^XiOXC^COt^tO-^rt V oc-Tt- — CO — rt^CO'*Oi V r-OO^OC^ — iCCO — -^05 il 03 r- coco(M Oi "m Z t. 4-' (0 ^ s o o -1^ w -c V c (0 o >, o ns c < a> O-^OXiOXiCOOOOO-- > GO r-^C^ClCC^OOOOt^-t^ «? 4> o ^ — C^ C^ !M t; W s 1 r" CO 05^_|__1_^1 -H ^ , — -— "3 ' c ^ Q-^-S to X X _j_ C-l c<> X ^ 2 '"' ^ C0XiO(N -}-4-C^ CO X ^ ^ , , t> (M ir-r T -0 S J8;:2+4-'^^ (N § OXXCC+ + -. Oi (M 1>.I:^ C<> ^ _|_— - '^f , t^ T— 1 + X ^^ 2"" 1 M c f« o X ^ <4- o 1- + X (U "^ " — ' J3 T! E < 3 z ^ r- Oi c: (N -- -H Oil> ^ t^ — "" Tf o s ^t^o-l++-. coc^ s- 4> n ■c c ■9r _o 03 t-"^ '^ CO c < 15 tt) E i c5 ^^ . i Hill II -11 5^ Ki. > 01 = 5 2.2 II 0) J) 74 FELDSPAR IN ILLINOIS SANDS O 1 - CO fe '^'^(N^tN^'-^'^ S V, ^ •!-• C V O L. 0) 0. ^1 t-HQOGOOCcOOOi— iiOt>. a> HH^^g^^'^^^^S .fi ^ 3 O <0 TJ O < 00 -rt* iO »o t^ -^ O 00 -O 0) r^ CO 3 O O^^ < ^g ■o c TJ^OCOOOOOCOCOGOCOOS 0(M05t>-(MrJ^iO<£i^O ^^ TS O ^co^ ^ c ■D M-c1« '^ C < Si C8 -U Oj QJ 15 C^(MTi^i0T^00(N'!j« .Q (M cDt- CiO OOiCO;-; O (N C -^ Qi COO-X^ »--H ^(MCO ^ a> . ^-^ O 0< 3 V. G^ 02 4) Q. -rs Oi(Mt^O0(N — O:C0rti0C(NC^r^ COrtllCiOCDC005^'-^00005 "tiCO(NiOOCOCX V ^^lOrfrfi^OliC— '---OCO^ c <5 ^(N (N Ci iZ 03 Z flj 1 L. V ns ^ 2 C o -*^ (0 0) (0 c c O as c < Xi. O^OOO^OOiCOOOOO'-; r-H ^ (N c^i CO ^ CO c o o t- r- J 1-1 ,-1 CN (M CI Q 9) Q) W S 1 Ih F Natural (est.) o + 00 I O >0 CO lO -^ _L CO (M Oi D Acid treated 00 IOIOC0 1C_|__|_(M 00 ^ CO Tt< 00 CO CO O CO ?^ F Natural (est.) o + T CO 1>. "* Tt^ 1^ ^ t^ ^ ^^ (M o 1 qI 8 1 00 CO 00 -H lO r-. O O Acid treated 00 1 ^lOOirfi— iO_l_ Tfl 1 00 1 thco 00 r-H C<> Tt* -^ 00 O T-l CO - ^ coio (0 C < c i c -3 C 6 ^ O ^ Quartz Potash feldspar Soda-Ume feldspar Shale, etc. Chert Heavy minerals Others Condition G" Total feldspar Acid treated Natural Condition H*- Total feldspar as sampled SIEVE AM) MIXERAL ANALYSES 75 o S o e O O (K -C i^ O ^ 03 •*■> ^ > g (MCt^CiOCcC;C(Nt>(M'-l:^t> < 3 -tj t^eociO(Nt^»--ioccooo5 > 03 1— 1 1-H T-H 1-^ ,-H 1-H 02 >^ 12; ^ 4-> c 0) O t- V Q. •^-' 0) ^ 3 O oo c ^c^-cc^^c^coog 3 O ^ £ < ■a c re ^ ^ ■a 0) c "re ■£ CC . . JC 'c3 O) < 3 ^^05kO00C0^Oc0r-^t-> ^ •M c a> O t- a> Q. >-' ^ OT 0) S 00 re <■ g 3 ^ ^ ^(N-^r-CCOCCOC^T— CO^ £ H ^ddocO'-^c^coco^c s. a> c il __ re E a> 4-> re S c •*- o '•+3 M V (0 6 re c < V ^ OrfOXiCXiCCCCCC — > 02 ^^CSJfNCOTtccCtOCt^t^ S3 a> O -H — (M c^(M t: ;^ S \b^ o CO CO CO CO 4__|_Oi r- F Natura (est.) + 8 ec 00 CO _|__|_eo cc ?5 1 »— 1 00 s flj Q-ts 00 eoiot^eo ^ o ^ (M (M CD -H ^ (N -o S < rfi (N 00 OC c3 (M r 3^ + 1- 00 1 iO ^^2"^++- l:^ T3 CO -d Q^ Qo-^ ^ SJ 00 «DO0 --H lO _l_0 ^ o -(J ■^ Oi o CO 00 -rf (M ^ 1 c^^ t- ^ -i- (M , t^ (M ce (N F atur (est.^ + Z 1 ^ CCOO+O^C. CO o (M '"' Q-ii CO CO C: to "^ + 4- ^ 00 iO o: — C<1 -- C; C^i ^ Ttl l> -- -M (M c CO t^ CO -^ r^ r-i ^ ^ l> l> --I (M F Natura (est.) + lO lOI>COCO .[.-H —1 O <£> (M T3 -T3 — (N ^ -: o -t.3 ^ ^ >. ^ c ^ M i£ j3 ^ 53 -rr <^ 1 g-C 03 6«1 - C a; O GO O 0) =l& uartz otash fel 3da-lime lale, etc hert eavy mi thers dition otal f( Acid Natu dition otal f( as sa se- sH ©•Cu^ooOffiO o d sS 76 FELDSPAR IN ILLINOIS SANDS 74 Outwash No None ■*-> X c V o 3 O O) ■a "o < c 3 O £ < ■a c ^~> ■a v c ns •i-i a> QC o 1- 4) Q. w m 00 c H t- c il "re V 4-> (Q H- o (0 0) (0 >» re c < > A Natural (Mrt^cOrfOC^l C^O E "re o o E 3 z ■M c o 1. (0 >» re c < "re L. -^ T^ iM CO !>. ^ tJH Tf ^ CO iO 1 (NOrt^COcOrfOtNfMfM li 03 O iCOiOCO _|_'-^ (N 2 Oi ^1 -- 1 s g t^O.O.rf+0- X -M c o c 1 t^ < 2 O 1 Xt^OCOO(N_i_ r- 1 H ^cocN-^ a: X l>- i:^ 10 1 ^ i>- Sample No.» Type of deposit Calcareous % retained on 8-mesh G O O -G O'^OOOu^OOiCOOOOO'— i:i^(NCNCOTt*cOOiOOt^b^J 1 . ^ 1 ^ c -3 G o o as g 'T3'*- . G 211 s tl 52 A 3; tH >• S oil-. -3 03 0^ ill ■lis r SIEVE AXD MIXERAL AXALYSES 77 '^i^i »o s - = Z*^ I ^ -^v ■4-' "15 OCCCrC — OCOCt-TM^iCC-l^C: ^1 TtoC — C-. 2Cr^t^rCC:C:C;t^5 ^ Z ^" >» Si +J c V O t- 0) Q^ V SI 3 O 0) ;p 13 c8 XrfiC-sCCO^fNCCrfX o < ^OOOTfiCaCC^CO—'CCOC: c z 3 O E < ■a c CB ^_^ TJ V E 're •f « QC •M . s (NCX'MOOC^C^I'N'^OC u ^ SI ♦J c V O i- (O Q. ^-' X (0 4) S 00 •— 1 re <5 — rr-t^TfrrC;Tr?C?CC^->C0C X H t^ ^' ^' ^ ^" ^' ^ ^ ^' ^' ^' _„ ^ 53 H~'"''— ?5!N-^ c; 1. z 0) c Ll re "il 0) *^ re ^ S C H- .2 o .ti OT »^ V M _-^ >. o re E < 4) ^ Ort-OXiCXiCOOOOC:-- > "k — — C^CSeO'<^:£C;»-':c:i:^t^ c3 0) © — — c^ c^ r-1 -:; W s [ r^ ^ §^^^r+'* ^ I> ^ (N + i^ ^ "x "P ^ c ;z:^ 1 1 . 00 i X CC CC Lt M _|_ — ^ 1 — 1 "»; 1 "2 £ oc •^1 ^ "^ "^ '^ '^ "^1 ^ C '^ (M let — — u 1 <: ^ :0 CO :£ cc ^ c; Lt ^ — -N ro — •M pi g-"'=4- ++^^ X '^^ (N 3 ^j + "-31 T z 1 2 ^'^■^+ + =^ - — — -■|"§ <| 00 g^CC-+0- "' X ^ -x^^+-^ (M , ?i (M ■^ -is + 00 1 1 1 t z"^ 1 1 ^ -M t^ -,C C^l 4_ — -M -^ ^ C^l " -r ? i^ M c: cc rc _!_ — ri ^ E -kj ioc - :r - - - - C - _ "^ t^ " — "^ "^ ri M (0 I E "re ^ ^.^^.^^__ X O ^ fi — o + I. SI ^^1 Z 00 1 E 3 z 1 S -a^--^'+-- ?1 >» , r^ 1 »-H Si ^11 1 ■4-) E 0) -J 00 g^^-^+O- I> X o 1 L. u 1 Q. f. - , ^-^ 5 1 "^ 1 ^ :S 5 1 fc-t; %. re E < o 1 if 1 — ^"^ "re '"■ £ "c ~ 1 H — ^ ^ .£ X V E »? — x: "t , >-. ? Hill II x| § 78 FELDSPAR IN ILLINOIS SANDS ^ 00 O OJ cc T3 1 rt^ 00 lO l> -H O CO lO (M 1 CO(M (N r- .-H ^ -d OJ 1 "oS o<: 3 ^1 ^^ .^ ccioco^^iooo C^COTt^(Mo6(N'Mrt^'o00005 "^ r^(MeO r-^ 05 -d OQ"o"S 4J O Q. '^ C^ CO O) O 00 --H 05 05 CO --^ b- c^ ^'*"^^^g2^^=^^^§ 3 O u ^1 CO •a o CO 00 o -^ iO -^ ■* t^ o; urj < CO -H 4-» -d 0) 3 o"^|! O E vo3 1 < ■o c « COOCOrt*iO-HcD— iiO(M— <^(M O^CO f- O) iO-HCO(NCOt>Tt<(N'X»s <^ ^ c3 1 ■»-• ^ 1 E 4> o t- 00C0O5'^iOC0» O ns E < 0) r^ Ort^OOOkOOOiOOOOOO — > --•^(NCNCOTt^cOOiOOt^t^ ^S 4) o; """7e2 5 S F Natural (est.) o 4- 00 1 O Tf O Tt^ O — CO CO ^ 1 ^ 1 1 Oi E Acid treated (est.) + lO lO t^ lO O — ' r-i 1 c. Acid treated GO 1 '-^lOt^'MiO.LI Tt< 1 00 i^~i 1 I CO OTt^ O O CC -H ^ O Total feldspar as sampled SIEVE AND MINERAL ANALYSES 79 m + -C5 o; r^Ot^rfrf^^i-"^ (MC^OOu^OeO'-'OOOOOO CO CO i-H C ^Ot^^t^CO'^iO^'^'-Hi-H(N C» re c < > .iO^ rt^OOCOCOtOOSCOOO T-< CO ■* 10 t^ O CO t>. 05 ^ o COCO (M ^ ^ — < g O5^COt^Tt O O^ Oi C^C)00iOX«OOOOOO-- '-^-ifNC^COrfOOiOOt^t^ o3 I H o F Natural (est.) + op 1 t^ -i^ Oi CO — CO 1 1 1 1 E Acid treated (est.) + 00 1 00 -- -^ C5 CO ^ Tt 1 , 1 1 '0 < ^ CO CO .-I -^ c^ 1 coco 10 CO 1 . IC CO 4.10 lO r-< ,— 1 <— 1 1 1 lOrf 1 F Natural (est.) + T 05 t^"* CO CTf CO(M _l_CO 1 !>. ^ i- 4- 00 1 CM -^3 ^ 00 n^ ■^ Tt CO t- 05 (N -^ -H COCO Ot^ ^ 1 ^^^ 00 CO CM F Natural (est.) + op 05Tf 00^ CO _|_(N 1 CM 1 1 1 00 E Acid treated (est.) + 00 1 t^ioaiTtico_^(N 1 ^ 1 1 1 1 ■3 t-H cOOOCM ^ _|_(M 00 ^ ^^ ^ 10 05 CO -rt^ (M + + Acid treated (N-^iOcOOCCOOOCli— 1 1-^ OOO(NO^cD00OO S-: t-^O ^^ CO HH o 2 03 (M Tjt CO CO kO CO (M ^ CO^ OOO(MOC0C000CO i^OC 1 A Natural cOrHOeocOr^coioco^ '^o 0^eCt^cOTf(Nrf<"oot^CO to i-Hr-^(M(McoTjoot^r^'? 1-H ,-H C^ (M (M -g 1 H + ococo-H i^'^ 2 2 Acid treated (est.) o t^ CO CO ^ _1_ ^ (M 1 Oi 1 8 iO t> TtH !-< O (M ^ 1 r^ ^ 1 S iO CO kO T-H 1^ C* O CO O ^ _1_ _L CO 1 CD to 00 1—1 1^ >^ 1 ^ ^ iO to 00 CO (M _1_ _1_ (N ^O CO t^ '-I 1^ 1^ (M (M 1 Natural (est.) o + 00 ^ lO i-H T-H ll(M 00 -H -t--t- CO CO -ri a; § oto^_^ 4.-^1 t^ J lO 00iOCO.-^»-i_l_(N CO t^ r^ + 00 % c3 ^o c % Acid soluble ■^ lO rr CO t> CO B Acid treated i-H T-H Ol CO I— 1 -^ (M ^ _ '^ A Natural ^^^rt^OCOCOrt^OO^ H^^-^^n^;:^^^! C % Acid soluble l>COCO(Mr^ i-H O O -^ CO CO '— 1 (N c,^ooooa:oc.oo^^g 03 1^ O O OOCO C35 O Ot^CO^ _^(N C0rt^c000iO05O(MOOr^OO c % Acid soluble (M A Natural OCO(MOC CO ^^ (M 03,^ CI + ^ 1 -d o CO E treate 3St.) op o, -d"-^ O ^ 00 CO QOCO -H _L.O(M 1— 1 T— 1 -<* C^ (N TS cu qI iC (M 05 rft r^ r-( O CO coco CO t- rH (M OCO ^ CO CO ^ co^^ CM (N (0 r (M 05 o I> 00 lO CO 01 --i rt^ CO t>. CO ^ (M O o F Natura (est.) 05 + 00 I- 1 ja F 3 z lO ^ i> CO CO '-^ T^ ^ CO CO !>. r-l (N 73 >» -C 1^ ja Q'S"^ C O 00 OOO^ CO ^ (M CO S- (U ^ § ^ ^ a> CO -5 ^ 03 c3 a^ 03 73 re c < 0) i S o Quartz Potash feldspa Soda-lime feld Shale, etc. Chert Heavy minera Others dition G" otal feldsp Acid treat Natural dition H^ otal feldsp as sample r 82 FELDSPAR IN ILLINOIS SANDS Qj X ~ ^ccc 0) ^ 00 c re X IS (MfNTt-OcC'-'OCCOtO-*^'-' E il re r-l CO C 0) ■M re •4- o V) >. re E < > (0 '■^ -S c o O x: 03 O OTtHOOOiOOCiOCCCCO-; -— '- C^ CO (N + "sS^-v 00 3 -t^ 1 JH ^ 02 ^3 o JCC^^_^.(N^ rt< L + Op CO sl"^ 1 (U -^^ *G < o O0CC0(M 000"* ^^ g CO (N COCO T3 -2 o ":> o CO CO c c^ »o iO lO qI :2 ^ (M coco -d 'S < o g;::?5'^++'^ rfi O o COCO CO o (M -^ CO CO '- CO t^ ^ t^ lO^ (01 CO {N "eS + 2-7 00 r 3 -t^ hlH 43 CC o Tt -- Tf CO ^ CO -^ iO T3 + iO-xC^ CO ^^ 00 w^-s 1 o rs"^ 'c < o Tt O O CM C »0 r-. 00 00 to iO (M coco " 1 c iC O -^ CO _l_ CO »o TtH Tf c coco iC 05 CO CO lO -^ CM -rfi COC. 02 §H gH o o SIEVE AND MINERAL ANALYSES 83 q; M fS 02 C Ci (» ^ c £: 53 X % Acid soluble !>-- ^ CC O — c V O t. 0) 3 O (0 "O o < 1 ^QOIXNOiiC^'-^CCO c 3 o £ < ■a c 're U 6^ 02 + + ■♦J c ^1 (M l> CO CO CO r^ C^ "* (N '-I y-' o t. Q. OT 00 c re x: 1- t. "re ^^^S^^^^-^^^HHg 1 iz; (N CX) 00 O Oi »0 Tt^ CO '-H r- ,— 1 (M 1— i(Ml>c0i00i00^OOf>"OO ■M re «♦- o (0 V (0 re c < > 1 c o o OTt^OGO"30CiOOOCOC'^ -^-^(^^(MeoT^«50toot^t^ =? rl 1-H (M (M (M -g o -* -H CO r-< T^ ■* CO-Hr^ (M (M o CO 1>- (M CO lO (M ^ _1_ ^ ?, iC 1 (M (M (M — ^ ^ _1_(M t- — -^ ^ ^^ E 3 CO (M 05 z r2 ' >% ^ 00 CO r^ lO (N CO O CO CO to c o (N CO -^'- (M Q. ^^ fl 02 (0 M -3 § 0) 03 as g 03 «^ 03X5 re < re 0) 2 II £ S'-- 03 .^ ^^ 02 i &^&§^§&6 O If 84 FELDSPAR IN ILLINOIS SANDS oorhcoor^+oo i^ t^ ^^ (M So + '2 oj fe5^ 00 1 02 t^ CO -^ 05 t>. 05 CO CO 533 ^ 1 *j ^1 CO CO C^ ^ T-H r- 1 (M (M (M JZ T3 oi 10 1^ CO 05 ^ CO (M •? -2^ t^ ^ ^ r-^ (M « 03 ^-v + 00 ^ >^ TB'^ 1 J3 '0 ' •«-• c t3 . Tt" ,-i(N 05C0 |CO CO 1-1 I— I 1—1 V 1 Q^ 1 o3 1 0) 00 rH Tt< Oi CO 00 (N COOi ^ D (M UO r-H ^ (M <-• 3 al O c/) ^O-^tr^cOOiiOTficO-^c^ltXJOs 1— I r« ^.^ V^rf I 1 ^vj T " >^^ \„^ V,^ -SI W^ < . o c3 T*^ Tt^ Tj^ Oi 05 00 CO COUO -^^Soo < ^ 1— 1 ^ --- - C^ r-^ ^■^'^^ c CO '■^ 3 rt O E O OOQOUO _^(M t- CO < _^ t^ . J ••-• l> C^ < 0) "^.^ C^ g g *1 H5| + 00 ^ -^ ^-^ 1 S < 1 Q ^ ^ <«) Q COO0C5 _|_OiOiO t^rH > >» COCO J3 d u •«-» 33-3 -§ --iioascooooooscoc^F^ M ^■^oo-c^^^co^'og 1 1 O <^ CD 00 c^ a,0(N _j_iO r-H ns 1 , ^ rt^ t^ l> I> TjH CO CO Oi E CO COCO f^ flj E^H°^-^;::S^'^'";::g 3 z 00 T-H CO ■>* CO CO CO t^ 10 95 Rive Yes Non. il .5 'il 0) •M ns 2 c 4) 4) rt^ CD^^ (MC^J CO C. G 43 1 Qi ^0 6 o (0 4) '^ 1 S ^ Sample No." Type of deposit Calcareous % retained on 8- M V CO >» m < -3 Ort^OOOiOOOiOOOOOO--; >■ re c < re t- 4> '3 a 1 Quartz Potash feldspar Soda-lime feldsps Shale, etc. Chert Heavy minerals Others idition G^ 'otal feldspar Acid treated Natural idition Hi- otal feldspar as sampled > 02 i-Hi— iC^c^COTfCDOiCOt^b- «S c 0) r^ .-H (M C^ (M ^ i a" SIEVE AXD MIXERAL ANALYSES 85 w a; 02 e '53 c '.a = O C 03 "C '^ " c c -a oi 'jll cc cr. % T3 25 _ — COCiTfOlrfiOt^CO'^ai Si ioO'-<"c;o5— ''co--ooo5 ■4J ^ (N CO CO Oi c -^ «> O « Q. ■^ V "5 — TfoOC^lCi-XJCO-^rt^tOX ^ b> 3 c 're +J 4) QC -« cu X qII CrtHOlOCiOit^Tf C; (M C^ — ^ 4) ssl ^ >s X -M c u O L. ^1 ■^OOCOTfOCOt^'+'M — -MO s. O — COw^iOOt^OOOOg ,^i X w V s 00 c re X 1 lOCOCOTMNiOt^C^lrt^'M — — C: d-^cod — rfOlb-OOO-^C: — c-i CO — cr. il ^ re L. 0) •M re i S _o «*- o _-'-' (0 "5 01 o >^ O re c < u _^ O-^OXJOGCiCOCJOOC: — > m rH^C^fNCOTf-OOlCOt^t^ li 4) ^ ^ -H C^ C^ (M -^ (^ % 1 r^ F^ o^t^co_^-.^ M , — r-' T3 -3 « ^"51 <3| »o CO Ci o CO — — 1 Ci CD r-" CO "" ^ CO -o; CO CO 'M -M — 2 — i^ fi CO — — ' + ^ ^ 02 X -s ^ Ci t^ ^ CO OJ 'M CO ^ f^ CO — ?i 'S^ (N ^-§1 X :2^ 1 1 'o w << c re lO CO CO 'Tf CO _|_ 'M ?M C O: t. y5 «M — O ■4- o -^ L. « 03 X (M iC (M 4_ C^l Oit- X s T*< £ r> fc. 3 _^ z <5 >% X X CO X^ CO -- O lO -M O CO \n -^ ^ CS (M C: O '^ t- 4) Q. f. •<_: ^-^ c -m M 4> CO >» .2 1 » 1 S3 ^ pj 55 & ^ ' ^1 ^-r re c < 6 i2 g i =11 "re -"Co; = 1 S-— -c 5 .X — ■ M I- 4) CiSkkOEC I sis r ^•-3 =1 ■I' 0) O) 86 FELDSPAR IN ILLINOIS SANDS ^ T3 cu o3 0<<^ Oi r-i CC •4-» ^i (N (M r-H O) 4) ^ >^ ^ ■4-1 -^ QCrt^ o <55 i- 03 Q. ^ ^ c r-toiOO — rO'MCOt^ Q T3 H^^^gS'-^^g E < -co; ■o -t-> c ns ^^ •u ^rt. ^ O^ 3 ^cO-^w(M^(MCOtC(MTtiOCOCOO^ (1) O^'ol^ ^ C-1 ^ r-< C5 S ^ s 00 £ m X 1- !- Or-'OsOeOOCIfNO^OliO'^T^ cOcDiCl>(MrJHr-^CCiiO (Q J2 2 c ««- o -•^ (0 (0 -73 re c < OTjHOOOiOQOiOCCOCC-- > «3 T-ii— iC^JC^COTticDOiOOt^t^il OJ ^^CqC^C;l-g - Ol + °f ^^ 1 3^ O 05 CC CC !M 1 C^l CO CO <-' ^ CI "S,^ (N + r2"^ 1 "C -»j CD (M ^ ,-H (M o C5 CO »0 CO -^ r-^ lO 00 l^ t^ '^^ C^J + T T^ o (N CO lO CO ■* ^ (M 00 V) E 2 00 o 3^ 1 o 'a L. V o (MCOCO 1 o ^ -^ 05 ^^ coco ^ o E t3 3 z 00 OOCOiO% Q^ -* ^ r2 E -< ^ Ort^»OCOt^_}_- 05 05 0) O CO t. a> Q^ § js s (0 ;^ s 03 ^T^ w -5 a t-l >» c b ^ i£ 03^ 03-0 o 5t3 03 T3 o^^ ao) re E < "re t. (U O NX!;::: , ^ >,^ cc -0 o "^ E i SIEVE AM) MIXERAL ANALYSES m CO 1=3 g a; s I ^ X '•^ ^ o o 1/^ "O £ ^— ~ "3 ^ "o3 aC rt^ CO CO — — ^s ••-' s: O) 0) ^ 1 03 lOCOst^ioeococOT^io^QOO SI :?; (U O t- V Q. "H <^ o^9 CO ^ — 3 f^^ O CO TJ U < 1 • 1 X(N(N(N-^C0^C0XcO»O(McO £ ^C^CMCO-^XXO-^iCC^cDOi 3 T-H Tf a; O 03 b ^ < "D C re -d OJ ■o O^l :n -x> t^ c (M "re ^g a> CC ■M X O) u ^ 1 cr. — — --cotj-coi-^ocOcnoc; >^ o3 — — rf* o: ja :zi ■!-• C a> O t- 4> CL 'H «i^ £ o^^ S 2 :f: M ^2 S 00 c re 1- ^ t^-^I>r^rt^T-H>O5rhiOC0iCt^ S C^COCacOrt^Xt^OiOOCO^Oi 0) c <5 03 rH rfi o; u. ^ re 1- 0) ** re ^ S ^ o -o 0) o >^ O re c < fl) D o-<*ioxiox»oooooo-— > OS ^^(M!MCOTfcOOiCCl:^l> ^ 9i Cu ^ ^ (M (M cs t; (h :§ Ih -o o X 05 CO t^ ■* CO CO IC t^ CO r-> -2 (N g^-^ + H^-S X -rs"--' rt^ — CO t^ t- CO — - "S^ c^ «^1 + T3-^ c- O X C^ r- ^ — ' X CO Tl t-- q; 1—1 03 qI X Xt^l>rr (N O (M Tt^CO 'c Tt^ I> < X CO rfi X CO a: O CO CN X (M ^^ (N ^^i + X ■n-^ 1 c < o X (M (M CO O _1_C<1 rtH (M -r! o C^ (N OJ 03 X (M lo t^ lo — c; 4. X ^ (M — < •^ X XiOCO^ — 1 C(M XiC (M lO ^ ,- r^ ,—1 ^- -d o '* oi a; X CO ^ CO 1 X ^ l> CO 03 .-V (M «-| + X ^s_. « <1 o »0(M X coc ^ »- c: t^ o l^ ^ CS r— '^ iO TjH (N C (M