n EMU VKBSBm HI i! mm ilgflBffwH sn Mil URBANA t STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON. Chief REPORT OF INVESTIGATIONS-NO. 22 REFRACTORY CLAYS IN CALHOUN AND PIKE COUNTIES, ILLINOIS BY J. E. LAMAR PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS 1931 STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION M. F. Walsh, Director BOARD OF NATURAL RESOURCES AND CONSERVATION M. F. Walsh, Chairman Edson S. Bastin, Geology William A. Noyes. Chemistry John W. Alvord, Engineering William Tkelease, Biology Henby C. CoWLES, Botany Charles M. Thompson. Representing the President of the University of Illi- nois STATE GEOLOGICAL SURVEY DIVISION M. M. Leighton, Chief Schnbpp& Barnes, Printers Springfield, III. 1931 48696—2500 Contents t 4. j j.- PAGE Introduction 7 Acknowledgments 7 Summary Areas discussed 9 Howell Hollow area Location and occurrence '. Geology „, 10 Clay resources Hannibal shale Occurrence and description Ceramic properties Possibilities of development Cheltenham clays .... * ]2 Occurrence and description Ceramic properties Chemical composition Possibilities of development „„ Loess 22 Clays in region adjoining the Howell Hollow area. DeGerlia Hollow area . . 23 Location and occurrence Geology 23 Clay resources Flint clay ' 24 Occurrence and description Fireclay 25 Occurrence and description Ceramic properties of flint clay and fireclay ' 25 Possibilities of development Origin of Calhoun County flint clays J Southern Calhoun County area ■* 9Q Location and occurrence Geology 29 29 Ceramic properties of clays Possibilities of development 80 Pittsfield area 35 OO Location and occurrence Geology 36 *>7 Ceramic properties Possibilities of development Sixmile Creek area. 40 Location and occurrence Ceramic properties 40 Possibilities of development . 41 43 Illustrations FIGURE PACK 1. Index map showing the relation of Calhoun and Pike counties to the rest of the State and the locations of the five areas described in the report. . 8 2. Topographic map of Howell Hollow area 9 3. Plat showing locations of prospect pits and borings in Howell Hollow area 12 4. Topographic map of DeGerlia Hollow area 23 5. Topographic map of Pittsfield and vicinity 37 6. Topographic map of Sixmile Creek area 41 Tabl es 1. Results of tests on Hannibal shale in Howell Hollow: Sample A Sample B 2. Records of materials penetrated by test-borings and pits in the Howell Hollow area 3. Results of tests on clay from localities in Howell Hollow area: Sample C, Harlow 40 Prospect 14 Sample D, North Johnson Prospect 15 Sample E, Johnson Prospect -, r Sample F, Old Open Pit Sample G, Old Open Pit 1 6 Sample H, Guthrie's South Pit 16 Sample J, Test shaft— lower white clay ' ' 17 Sample K, Test shaft— upper white clay is Sample L, Test shaft— lower blue-gray flint clay 19 Sample M, Test shaft— upper yellow flint clay 2 4. Chemical analyses of clay from Howell Hollow area ' 22 5. Results of tests on clay from DeGerlia Hollow: Sample N, flint fireclay Sample O, fireclay 6. Results of tests on clay from plant of Thomas Pressed Brick Company ' Southern Calhoun County: Sample P, underclay of Golden Eagle coal 31 Sample Q, underclay of Golden Eagle coal 32 Sample R, maroon shale above Golden Eagle coal 33 Sample S, clay above maroon and green shale 34 7. Results of tests on clay in the Pittsfield area: Sample T, two miles north of Pittsfield 38 Sample U, outcrop along Honey Creek 8. Results of tests on clay in the Sixmile Creek area: Sample V, Test pit 42 REFRACTORY CLAYS IN CALHOUN AND PIKE COUNTIES. ILLINOIS By J. E. Lamar INTRODUCTION The clay and clay products industry is Illinois' second largest mineral industry and its pits and plants are widespread throughout the State. Calhoun and Pike counties, however, have hut small representation in this extensive industry, despite their large and varied clay resources. It is the purpose of this report to call attention to the clay resources of these coun- ties, particularly fireclays and recently discovered deposits of flint clay. Detailed and reconnaissance data concerning clays in these counties have been accumulating for some years. Although the information at hand is not sufficiently complete to permit a detailed report, the current interest in re- fractory clays make it desirable that this data be published in order to render all possible assistance in outlining and developing the western Illinois deposits. ACKNOWLEDGMENTS Mr. W. A. Guthrie of Nebo and Mr. W. G. M'arqua of Pleasant Hill willingly assisted and cooperated in the study of the clays of the Howell Hollow and Sixmile Creek areas and furnished many outcrop data, results of borings, and ceramic and chemical analyses of a number of clay samples, except as otherwise stated in the discussion of the Howell Hollow area. The assistance of Messrs. T. B. Root, H. A. Sellin, and R. W. Gilson, all members of the Illinois State Geological Survey staff, is gratefully acknow- ledged in connection with the field investigations incident to this report. Mr. W. W. Rubey, of the U. S. Geological Survey, kindly furnished many data and offered valuable suggestions and criticisms of the manuscript. SUMMARY Flint clays occur near Bellevievv in northern Calhoun County and near Hardin in central Calhoun County ( Fig. 1 ) , apparently occupying depres- sions, probably ancient sink holes, in the Burlington limestone. The two ex- posures observed exhibit two kinds of flint clay, an upper buff clay and a low- er dark gray clay. According to results of tests, the lower dark clay is highly 7 BEFBACTOBT (LAYS l.\ ( Al.lIol'X refractory and comparable to the best Missouri smooth flint clays, whereas the upper buff clays are somewhat less refractory. The outcrops are not of great importance in themselves but establish the existence of flint clay in Illinois and suggest that prospecting may discover additional deposits in Fig. 1. Maps showing relation of Calhoun and Pike counties to the rest of Illi- nois and the locations of the various areas discussed in the report: 1, Howell Hollow; 2, DeGerlia Hollow; 3, Southern Calhoun County; 4, Sixmile Creek; 5, Pittsfield. the vicinity of the known exposures and possibly in adjoining areas. High grade fireclays are associated with the flint clays and appear to be extensive in certain areas. No diaspore clays were observed. AM) PIKE COUNTIES, ILLINOIS 9 A variety of clays, many of them of about the same quality as those in Calhoun County, occur also in Pike County. In southern and western 1'ike County there may he deposits of flint clay. In the vicinity of Pittsfield, there are deposits of good quality refractory clay which have been worked to a limited extent in times past. Clay of similar quality has been dis- covered near Pleasant Hill. In general the clay resources of Calhoun and Pike counties have been barely touched and exploration will probably reveal numerous additional R.4 R.3W. ■'^ v3~ ■ -■■■/■ i? '• I Mile Fig. 2. Topographic map of the Howell Hollow area, in- dicating the topographic position of the various points shown in figure 3, page 12. (Part of Nebo quadrangle map.) deposits of high grade clays. The completion of the deep waterway from Chicago to the Gulf of .Mexico should encourage development of some of the deposits along Illinois River, which are now not of great commercial value because of the lack of transportation. AREAS DISCUSSED The report describes the following five areas (fig. 1 ) : ( 1 ) the Howell Hollow area near Belleview in Calhoun County, (2) the DeGerlia Hollow 10 REFRACTORY CLAYS IX CALHOUN area near Hardin in Calhoun County, (3) the Southern Calhoun County area at the extreme southern tip of Calhoun County. ( 1) the Pittsfield area in Pike County, and (5) the Sixmile Creek area near Pleasant Hill in Pike County. HOWELL HOLLOW AREA Location- and Occurrence The Howell Hollow area lies south of the valley of that name in sec. 1. T. 8 S., R. 1 \Y., and sec. 6, T. 8 S., R. 3 W., about two miles north of Belleview, four miles southwest of Nebo, and about live miles southeast of Pleasant Hill. It is a part of the uplands bordering the Mississippi River flat and consists of narrow sinuous ridges between steep sided, nar- rpw valleys (fig. 2, p. !» ). Geology The bedrock of the Howell Hollow area helongs to the Mississippian and Pennsylvanian systems, as shown below : Bedrock formations exposed in the Howell Hollow urea Thickness Feet Pennsylvanian system Pottsville formation Cheltenham (?) member Clay, gray, white, and buff 0-15 Mississippian system Burlington and Fern Glen formations Limestone, coarsely crystalline, cherty, white 60 + Chouteau formation Limestone, buff, dolomitic 10-20 Hannibal formation Shale, greenish, hard, well bedded 30+ Of the Mississippian formations the Burlington outcrops most exten- sively and with the Chouteau forms the backbone of the ridges and hills of the region. The Hannibal shale appears beneath the Burlington limestone in a few places, but in general it is not widely exposed. Above the Burlington limestone lie the most important clay strata of the region. A study of fossil plants from these clays indicate that they are almost certainly of Pennsylvanian age, probably a part of the Pottsville formation. 1 Tliev are therefore tentatively correlated with the Cheltenham clays of the Pennsylvanian system. The contact of the limestone with the overlying clays could be studied only in Guthrie's old open pit (fig. 3) where the clay fills hollows between 'White, David, personal communication to W. W. Rubey. AND PIKE COUNTIES, ILLINOIS 11 projecting ridges and knobs of the limestone. Although the contact may not be precisely of this character everywhere, it is believed to he generally irregular. Normally the clays are overlain by a thin layer of brown and white chert gravel which is probably Lafayette (Pliocene) in age. A deposit of Pleistocene loess or wind-blown clayey silt covers the tops and flanks of the ridges to a depth of 25 to 30 feet and generally obscures the underlying clays and rock. Clay Resources Hannibal Shale occurrence and description The Hannibal shale outcrops at intervals along the south wall of Howell Hollow, especially in the N. l/o sec. G, T. 8 S., R. 3 W. It is a greenish, gritty, well bedded shale, which weathers to a greenish, plastic clay. CERAMIC PROPERTIES Results of ceramic analyses on two samples of Hannibal shale are given below : Table 1. — Results of tests of Hannibal shale Sample A NW. corner, SW. % NE. % sec. 6, T. 8 S., R. 3 W. Shale, greenish-yellow, very hard; when mixed with water it shows a moder- ate plasticity; sticky when plastic. Drying shrinkage per cent 5.92 Burning test: Cone Porosity Per cent Shrinkage Per cent Color 03 3 30.2 4.5 3.85 19.0 light red gray-green SUMMAKY Suitable for making common brick and tile, and probably for light weight, burned clay aggregate. Sample B SW. % SW. % NW. 14 sec. 6, T. 8 S., R. 3 W. Shale, greenish, does not develop plasticity. Drying shrinkage per cent 7.59 Burning test: Cone Porosity Per cent Shrinkage Per cent Color 03 3 19.6 3.9 9.5 17.4 good red light red L2 Khllt.U TOHY (LAYS IN CALHOUN Summary Nonrefractory clay, suitable for brick and tile, and probably for light weight, burned clay aggregate. These analyses show that the Hannibal shale is suitable for the manu- facture of brick and tile, and probably for light weight, burned clay aggre- gate. ( )ther higher grade ceramic prodttcts can probably be made from the shale if some of the fireclay of the Howell Hollow area is mixed with it. Possibilities of Development The total thickness of the Hannibal shale in the area is roughly 75 feet, but only about 40 feet of the shale is above the level of the valley flat. A considerable amount of the shale could be obtained by working along the outcrop but if large scale production were undertaken mining would be eventually necessary. The limestone overlying the shale is generally solid and unbroken and would therefore make a good roof if the shale were mined. Cheltenham Clays occurrence and description Clays have been discovered in pits or borings at a number of points (fig. )5 and Table 2) on the divides in the Howell Hollow area and are de- scribed as red, blue-grav, gray, and white at different places. Although the available data, are from diverse sources, it is reasonably certain that there MARQUA'S DRIFT MINE N JOHNSON PROSPECT N 4 JOHNSON PROSPECT 10* 680 ' BORING NO. 3 3 »6V6 ■ OLD OPEN PIT.?, HARLOW 40 PROSPECT GUTHRIE'S DRIFT WINE " 670 ' §TEST SHAFT 690 ' 1000 I , 1500 FEET ,1 BORING NO I B0 R| NG N0 . 2 7*22 ■ Z *709 ■ BORING NO. A ^•676 ' GUTHRIE'S SOUTH PIT**.. . Fig. 3. Plat showing locations of prospect pits, borings, etc., in the Howell Hollow area. The three-figure numbers give the elevations of the top of the light colored clay; the vertical numbers are for reference to figure 2 and the text. Locations on this map were made by planetable survey. AND PIKE COUNTIES, ILLINOIS 13 Table 2. — Records of material penetrated by test-borings and pits in Howell Hollow area Thickness Thickness Feet Fee* Boring No. 1 Guthrie's Drift Mine Dirt 27 Clay, gray Johnson Prospect 6 Clay, red 1 2 7 + Clay, white 5 Dirt Boring No. 2 30 1 North Johnson Prospect Clay, thickness not known. Guthrie's South Pit Gravel .... Clay, red 2 8 0-2 Clay, white and blue 9 Boring No. 3 Clay, gray 8 Soil, gravel, and red clay. . . . 30 Harlow '/') Prospect Clay, white Shaft Clay, gray Mar qua' s Mine 5 Dirt 27 % Gravel, chert and limestone. . 6 Gravel .... 0-4 Clay, red 2 10 Clay, white 3 Clay, hard, standing blue and yellow, side by side 6 Old Open Pit Loess 10 + 0-6 Clay, white 4 Gravel, chert Limestone Clay, gray and white; an ir- Boring No. .} regular thickness of clay ly- Dirt, gravel, and red clay. . . . 28 ing between ridges of lime- Clay, white 14 + 3-10 are rarely more than three distinct beds of clay. It is known further that a light colored gray, huff, or white clay as much as 14 feet thick (boring No. 4; hgs. 2 and 3 and Table 2) constitutes the main body of the deposit and this clay is tentatively correlated with the Cheltenham member of the Potts- ville formation. It is normally overlain by about 2 feet of red clay whose age is uncertain and may be Pennsylvanian or post-Pennsylvanian. At some places; the light colored clay is all the same, but at others as in a shaft dug on the top of one of the ridges ( No. 6, figs. 2 and 3, Table 2 ), a bed of hard, blue and yellow flint clay occurs between two white clays. It seems reasonably certain that the major portion of the ridges in the Howell Hollow tract are capped by the light colored clay overlain by the red clay, over which there is a thin stratum of gravel and then loess. The extent of the flint clay included in the light colored clay is much less certain. In the record of materials penetrated in the shaft it is described as "blue and yellow standing side by side", but those who dug the shaft report that 14 BEFEACTOEI CLAYS IN CALHOUN the yellow flint clay overlay blue clay, both beds being variable in thickness and probably lenticular. The flint clay deposits of .Missouri, which seem to be of about the same occurrence and character as those of Illinois, are Known to be deposits in ancient sinks and are therefore limited in extent. Although there arc no data to show definitely that the flint clay in the Howell Hollow area is in an ancient sink, there is reason to believe that it is, in which case it may not be of sufficient extent to be commercially important. 1 lowever, the known exposure does indicate the presence of Hint clay in the area and encourages further search for this valuable clay. CERAM [C PROPERTIES 'I'he uppermost red clay is of variable character. At >ome places it contains chert fragments and at others it is relatively free from extraneous material. It is ordinarily plastic and sticky. It has never been tested to determine its value for ceramic purposes, including light weight aggregate, but it is probable that the non-pebbly material might be used in foundries as a clay bond for molding sand or be mixed with other clays either to give them plasticity or to lend a red color to the finished product. Samples of the light colored, gray, buff or white clay, taken from vari- ous pits and openings in the area have been tested and are reported upon in Table 3. Table 3. — Results of tests on clay from localities in Howell Hollow area (See Figs. 2 and 3 and Table 2) Sample C Harlow J0 Prospect ('lay, buff-colored; molds well when plastic although slightly sticky. Modulus of rupture lbs. per sq. in. 254 Screen test : Residue Mesh Per Cent 80 4.4 100 2.25 Drying shrinkage l>cr cent 7.12 Burning test: Cone Porosity Per Gent Shrinkage Per cent Color :: 6 10 23.0 17.5 13.0 8.2 8.3 24.8 cream cream cream Fusion (Deformation) test: P. C. E., Cone 26 (approximately 3002° F.) Sl'MMAUY A refractory clay, suitable for fire brick, face brick, stoneware, terra cotta, sanitary ware, and for stove, ladle, and flue linings. AXD PIKE COUNTIES, ILLINOIS 15 Sample D North Johnson Prospect Clay, dull, straw-colored; molds well when plastic. Modulus of rupture lbs. per sq. in. 217 Screen test: Residue Mesh Per Cent 80 3.0 100 0.8 Burning test: Cone Porosity Per cent Shrinkage Per cent Color 3 6 10 16 8 1.4 20.3 23.0 30.5 dark cream cream gray white Fusion (Deformation) test: P. C. E., Cone 29 (approximately 3310° F.) Remarks: Seems rather slow to oxidize. Summary A refractory clay, suitable for fire brick, face brick, stoneware, terra cotta, sanitary ware, and for stove, ladle, and flue linings. Sample E Johnson Prospect Clay, tan-colored, plastic, very sticky. Modulus of rupture Screen test: Mesh 80 100 Burning test: lbs. per sq. in. 465 Residue Per Cent 5.75 1.47 Cone Porosity Per cent Shrinkage Per cent Color 3 6 10 6.8 2.87 18.5 m 20.0 " 49.9 gray gray buff Fusion (Deformation) test: P. C. E., Cone 23 (approximately 2894° F.) Remarks: Clay seems to be rather slow to oxidize. Summary Suitable for the manufacture of brick and tile. Sample F Old Open Pit Clay, light buff, very plastic, molds readily. Modulus of rupture . lbs. per sq. in. 348 16 UKI'RACTOUY ('[.AYS IN CALHOUN Screen test: Drying shrinkage. Burning test: Mesh 80 100 Residue Per Cent 3.45 0.97 .per cent 7.15 Cone Porosity Per cent Shrinkage Per cent Color 3 6 10 4 1.7 20.7 23.5 29.6 gray white gray white gray white Fusion (Deformation) test: P. C. E., Cone 26-27 (approximately 3002°-3038° F.) Summary A refractory clay, suitable for face brick, stoneware, sanitary ware, terra cotta, fire brick, crucibles, and for stove, ladle, and flue linings. Sample G Old Open Pit Clay, light, buff-colored, molds well when plastic. Modulus of rupture lbs. per sq. in. 233 Screen test: Residue Mesh Per Cent 80 3.92 100 1.7 Drying shrinkage per cent 7.15 Burning test: Cone Porosity Per cent Shrinkage Per cent Color 3 6 10 15.3 12.6 3.5 24.2 23.4 25.0 cream cream gray white Fusion (Deformation) test: P. C. E., Cone 27-28 (approximately 3038"-3074 c F.) Summary A refractory clay, suitable for fire brick, face brick, stoneware, terra cotta, sanitary ware, and for stove, ladle, and flue linings. Sample H Guthrie's South Pit Clay, buff-colored, molds well. Modulus of rupture . lbs. per sq. in. 242 AND PIKE COUNTIES, ILLINOIS 17 Screen test: Drying shrinkage. Burning test: Mesh 80 100 Residue Per Cent 3.0 1.12 .per cent 7.19 Cone Porosity Per cent Shrinkage Per cent Color 3 6 10 20 15 12.5 14.6 15.3 26.9 cream cream cream Fusion (Deformation) test: P. C. E., Cone 29-30 (approximately 3074°-3110° F.) Summary A refractory clay, suitable for fire brick, face brick, stoneware, terra cotta, sanitary ware, and for stove, ladle, and flue linings. Sample J Test Shaft — •lower 4 feet white clay a Kind of material No. 2 fireclay Reaction for carbonates None Reaction for pyrites None Color Light gray Working property Good ; plastic Conduct when flowing through a die Fair; tears a little at corners Drying conduct Good, no warping or cracking Volume shrinkage per cent 23.7 Linear shrinkage per cent 7.4 Water of plasticity per cent 25.9 Shrinkage water per cent 12.5 Pore water per cent 13.4 Transverse strength tests of unburned clay: Modulus of rupture with 50 per cent standard sand Lbs. per sq. in 244 Number of Briquettes 14 Modulus of rupture without sand Lbs. per sq. in 279 Number of Briquettes 15 Fineness test: Residue Character of Mesh Per cent Residue 10 Trace 20 Trace 48 0.8 Sandy 100 3.3 Sandy 200 7.3 Sandy Through 200 88.5 a Tests made by Ceramic Engineering Department, University of Illinois, for the Illinois State Geological Survey. 18 HKI'RACTORY (LAYS IN CALHOUN Burning test: Burning shrinkage Total Shrinkage Porosity Cone Linear Per cent Volume Per cent Linear Per- cent Per cent Color Hardness 2 5.2 14.8 12.6 19.9 light buff almost steel hard 4 5.9 16.6 13.3 17.2 light buff steel hard 6 5.9 16.6 13.3 17.6 light buff steel hard 8 6.6 18.5 14.0 16.2 light buff steel hard 10 7.7 21.3 15.0 7.3 light gray steel hard 12 8.4 23.1 15.8 7.8 light gray steel hard 13 9.0 24.6 16.4 4.4 light gray steel hard Oxidation conduct Easily oxidized Soluble salts Vanadium ( ? ) Soluble sulfates None Fusion (Deformation) Test: P. C. E., Cone 30 (approximately 3002° F.) Warpage None Suggested uses: As a refractory bond clay and in the manufacture of conduit, flue lining, stoneware, terra cotta, face brick, etc. Remarks: Best burning range, cones 4 to 8 inclusive, for color. Sample K Test Shaft — upper white clay a Kind of material No. 2 fireclay Reaction for carbonates Small amount Reaction for pyrites None Color Light buff Working property Good; plasticity excellent Conduct when flowing through a die _ Satisfactory Drying conduct Trace of scum ; no warping or cracking Volume shrinkage per cent 29.7 Linear shrinkage per cent 9.1 Water of plasticity per cent 28.0 Shrinkage water per cent 15.4 Pore water per cent 12.6 Transverse strength tests of unburned clay: Modulus of rupture with 50 per cent standard sand Lbs. per sq. in -62 Num ber of Briquettes 13 Modulus of rupture without sand Lbs. per sq. in 4 s:; Number of Briquettes 1;; (/Tests made by Ceramic Engineering Department, University of Illinois, for the Illinois State r.eological Survey, AND PIKE COUNTIES, ILLINOIS 19 Fineness test: Mesh Residue Per cent Character of residue 10 0.1 Pebbles 20 Trace Pebbles 48 0.1 Sandy- 200 3.5 Micaceous, sandy Through 200 96.1 Burning test: Burning shrinkage Total Shrinkage Linear Per cent Porosity Per cent Color Cone Linear Per cent Volume Per cent Hardness 2 5.7 16.1 14.8 13.0 cream almost steel hard 4 6.4 18.1 15.5 10.1 dark cream steel hard 6 6.4 18.0 15.5 11.1 dark cream steel hard 8 8.1 dark cream steel hard 10 7.6 21.0 16.7 4.4 gray steel hard 12 7.5 20.9 16.6 3.0 gray steel hard (blistered) 13 4.6 13.2 13.7 13.5 gray steel hard Oxidation conduct Easily oxidized Soluble sulfates Trace Fusion (Deformation) Test: P.C.E., Cone 28 (approximately 2939° F.) Warpage Slight Suggested uses: Light colored brick, terra cotta, stoneware, probably flue lining and conduits. Remarks: Best burning range cones 4-8 inclusive. Color quite uniform. Over- burned at cone 12. Sample L Test Shaft — lower blue-gray flint clay a Kind of material Flint fireclay Reaction for carbonates None Reaction for pyrites None Color Gray Hardness Hard Working property Poor; very little plasticity Conduct when flowing through a die Poor Drying conduct Good 8.9 2.9 18.7 4.8 13.9 Volume shrinkage per cent Linear shrinkage per cent Water of plasticity per cent Shrinkage water per cent Pore water per cent a Tests made by Ceramic Engineering Department, University of Illinois, for the Illinois State Geological Survey. 20 UKI Ii-UTOKY CLAYS IN CALHOUN Transverse strength tests of unburned clay: Modulus of rupture with 50 per cent standard sand Lbs. per sq. in 107 Number of Briquettes ' 13 Fineness test: Impossible to slake down for screen analysis. Burning test: Burning shrinkage Total Shrinkage Linear Porosity Per cent Color Cone Linear Volume Hardness Per cent Per cent Per cent 2 7.6 21.2 10.5 24.5 white soft (all bars have green scum) 4 9.0 24.6 11.9 21.1 light cream medium 6 9.7 26.3 12.6 18.4 light cream almost steel hard 8 10.2 27.6 13.1 16.2 light cream steel hard 10 12.2 32.3 15.1 14.1 light cream steel hard 12 11.7 31.2 14.6 13.6 light gray steel hard 13 12.4 32.8 15.3 12.3 light gray steel hard Oxidation conduct Easily oxidized Soluble salts Vanadium Soluble sulfates None Fusion (Deformation) Test: P. C. E., Cones 33-34 (approximately 3173°-3200° F.) Warpage None Suggested uses: A very refractory clay, equal in refractoriness to the best of Missouri smooth flints. The firing shrinkage is somewhat excessive but the clay should be valuable in the manufacture of No. 1 refractories. Has sufficient strength to be used for dry press, 100% flint clay brick. Sample M Test Shaft, upper yellow flint clay" Kind of material Low grade flint fireclay Reaction for carbonates None Reaction for pyrites None Color Yellow Working Property Poor; very little plasticity Drying conduct Good Volume shrinkage per cent 12.8 Linear shrinkage per cent 4.1 Water of plasticity per cent 25.0 Shrinkage water per cent 7.4 Pore water per cent 17.6 Conduct when flowing through a die Poor Transverse strength tests of unburned clay: Modulus of rupture with 50 per cent standard sand Lbs. per sq. in 119 Num ber of Briquettes 13 a Test made by Ceramic Engineering Department, University of Illinois, for the Illinois State Geological Survey. AM) PIKE COUNTIES, ILLINOIS Fineness test: Impossible to slake down for screen analysis. Burning test: Burning shrinkage Total Shrinkage Linear Per cent Porosity Per cent Color Cone Linear Per cent Volume Per cent Hardness 2 11.5 30.6 15.6 19.8 salmon pink 4 12.5 33.0 16.6 16.3 salmon pink steel hard 6 13.0 34.2 17.1 15.5 salmon pink steel hard 8 13.9 36.1 1S.0 14.6 pinkish tan steel hard 10' 15.0 38.5 19.1 11.3 rusty brown steel hard 12 15.2 39.1 19.3 10.0 darker brown steel hard 13 10.5 28.3 14.6 9.2 dark brown steel hard Oxidation conduct Easily oxidized Total soluble salts Vanadium ? Soluble sulfates None Fusion (Deformation) test: P.C.E., Cone 28-29 (approximately 2939°-2984° F. ) Warpage None Suggested uses: Would be useful with plastic fireclay of excessive shrinkage in making No. 2 refractories. Not sufficiently plastic to be used alone. Remarks: Peculiar because of dark red color and apparent refractoriness through- out wide temperature range The foregoing analyses show that the clays of the Howell Hollow area are generally refractory and are suited to the manufacture of a wide variety of products. Because they are refractory, the clavs are probably not well adapted to making light weight, burned clay aggregate by processes now used commercially. The samples from the Harlow and Johnson prospects (Table 3 — C, D, and E ) were taken relatively near the outcrop of the clay beds and may not be as representative of the deposits nor as reliable in showing the true character of the clay as those taken from the mines or the shaft. The deposit in the Johnson prospect (Table 3, Sample E) appears to have been mixed with loess, or altered bv the infiltration of soluble salts from the over- lying loess. The flint clay appears to be of two grades (Table 3, Samples L and M ). The lower clay is of very high quality and is equal to the best Missouri flint clays. It is highly refractory and burns white or gray. The "upper yellow" flint clay is also of good quality but is somewhat less refractory than the gray clay and burns to a pink or brown color. CHEMICAL COMPOSITION Available chemical analyses of the Howell Hollow clays indicate that they are relatively high in alumina and low in impurities. (Table 4). The gray flint clay closely approaches true kaolin in chemical composition. 22 KKIKACTOKY CLAYS I.\ CALHOUN Table 4. — Chemical analysis of clay (See fig. 3) "Old Open Pit" "Old Open Pit" Shaft Chemical Upper, soft, white, Lower, grayish- Lower, gray, flint constituents plastic clay white, hard clay clay « per cent per cent per cent Silica 52 00 57 24 45.17 38.78 33.39 30.74 2.21 1.74 1.78 Magnesium oxide 0.84 0.30 0.07 Calcium oxide. . . Trace Trace 0.71 Sulfur trioxide. . . 0.33 Loss on ignition. 11.52 10.03 13.16 a Analysis made by Chemistry Department, University of Illinois, for the Illi- nois Slate Geological Survey. POSSIBILITIES OF DEVELOPMENT The clays, except the flint clay, are plastic when wet, so that from time to time they may have flowed slightly. If this has occurred, the deposits should be somewhat thinner and lower in the margins of the rides than in the crests. In other words, as a clay bed is followed into the ridge from the out- crop it will probably be found to "rise in the hill" and possibly to thicken. Limited field observations confirm this suggestion. The light colored clays will probably be found to form a relatively con- tinuous sheet or stratum on divides where the clays are present. Some lat- eral variations may occur but it is believed that the general character of the clays will be relatively constant. The flint clays are probably more or less lenticular, and it is recom- mended therefore that test-borings spaced 100 feet apart be made to ascer- tain the extent of the deposit before development of these clays is attempted. If borings spaced at this distance do not distinctly outline the flint clay, ad- ditional borings at closer intervals should be made. The borings should be made with an auger or other instrument that will yield uncontaminated samples, which should be carefully examined to determine the thickness and character of the flint clays and saved for testing. Prospecting for new deposits in the vicinity of Howell Hollow is like- ly to be most fruitful on the hills having an elevation of more than 725 feet and outcrops of clay are most likely to be found on the flanks of such hills between elevations of 665 and 700 feet. Test-boring, followed by the dig- ging of test pits, is recommended for exploration of deposits. Loess The loess in the Howell Hollow area is not known to have been tested to determine its ceramic properties. However, loess from other parts of AND PIKE COUNTIES, ILLINOIS 23 the State has been tested and that which is not calcareous is useful in mak- ing common brick and tile. The upper, leached portion of the loess in the Howell Hollow area presumably could be used for the same purposes. Tests may show that it is adapted to making light weight, burned clay aggregate, and other special uses may probably be developed for it by mixing with it other higher grade clays. Clays in Region Adjoining the Howell Hollow Area Outside the Howell Hollow area, clay outcrops are reported at several places but it is not known whether or not these reported exposures represent deposits large enough to be of commercial importance. Detailed prospect- ing in northern Calhoun and southern Pike counties may reveal additional deposits of clays generally similar to the Howell Hollow deposits. DeGERLIA hollow area Location and Occurrence Flint clay crops out in two small valleys tributary to DeGerlia Hollow in the SW. ]/ A SE. y A SE. % sec. 8, T. 10 S., R. 2 W.. on the Hazelwonder farm about 3 l / 2 miles northwest of Hardin, Calhoun County (fig. 4). The deposit lies well down the east slope of the sinuous, north-south ridge that R. 2W. 1 ". 4 ■- ;• i ■<*?• jF-lre-'TC Fig. 4. Topographic map of DeGerlia Hollow area showing loca- tion of outcrop of flint clay. (Part of Hardin quadrangle map.) forms the watershed between Illinois and Mississippi rivers. The elevation of the uppermost flint clay of the deposit is approximately 720 feet, 2 which is only slightly higher than the fireclay and flint clay in the Howell Hollow area. 2 Rubey, W. W., personal communication. 24 REFRACTORY CLAYS IN CALHOUN Geology The mode of occurrence of the clay is not exactly known, but it prob- ably rests on or against the Burlington limestone which forms the core of the ridge, and it may occupy an old sink hole. The observed outcrops were small but the following sequence of strata was determined : Composite geologic section in tributaries of DeGerlia Hollow Thickness 12. Covered, mostly loess 11. Clay, white, stained brown and yellow by iron oxide; contains fragments of chert 10. Covered 9. Flint clay, light gray, weathers tan 8. Covered 7. Flint clay, light gray, weathers tan 6. Covered 5. Flint clay, medium to dark gray 4. Covered 3. Flint clay, medium to dark gray (Table 5, Sample N) 2. Clay, soft, white, plastic; contains small calcium carbonate pellets and is locally stained slightly yellow by iron oxide (Table 5, Sample 0) 1. Covered Clay Resources Flint Clay occurrence and description If the interval including and lying between beds 3 and 9 in the above geologic section is composed entirely of clay, as suggested by the frequent outcrops of the clay between the uppermost and lowermost exposures, there is 113^> feet of flint clay in the DeGerlia Hollow area. There appear to be two grades of flint clay in this area, as in the Howell Hollow area. Beds 3 and 5 in the DeGerlia Hollow geologic section are dark gray and are pos- sibly the equivalent of the bottom flint clay in the Howell Hollow test shaft, whereas the upper light gray or tan clay, beds 7 and 9 in the DeGerlia Hol- low section, seems equivalent to the upper flint clay in the Howell Hollow test shaft. If the covered interval 4 in the DeGerlia Hollow section is dark gray flint clay, this variety of clay has a total thickness of 4 feet 9 inches; similarly, if the covered interval 8 is light gray clay, the light clay is 4 feet 6 inches thick. The covered interval 6, comprising 2 feet 3 inches of the sec- tion, may be either or both light or dark colored flint clay. Feet Inches 1 3 2 1 2 6 1 2 3 6 1 6 2 9 1 6 1 6 AND PIKE COUNTIES, ILLINOIS 25 Fireclay occurrence and description Lying below the flint clay is a deposit of soft, white plastic fireclay represented by bed 2. Above the flint clay is another white clay, bed 11, containing fragments of chert. Although only iy 2 feet of the lower clay is exposed, a greater thickness of this clay may be present. The upper cherty clay also may be thicker than at the outcrop and possibly largely free from chert. CERAMIC PROPERTIES OF FLINT CLAY AND FIRECLAY According to the results of tests on sample N taken from bed 3, this clay is a high grade flint clay equal in refractoriness to the best Missouri smooth flint clays. (Table 5, Sample N.) Tests on sample O taken from bed 2 show that, despite its content of small pellets of calcium carbonate, it is a good grade fireclay (Table 5, Sam- ple O). Table 5. — Results of tests on clay from the DeGerlia Hollow Sample N Outcrop in the SW. hi SE. V± SE. % sec. 8, T. 10 S., R. 2 W.« Kind of material Flint fireclay Reaction for carbonates None Reaction for pyrites None Color Silver gray Hardness Very hard for raw clay. Can be scratched with fingernail with some difficulty. Working property Works very well and easily after the first few minutes of wedging. Drying conduct Can be dried very quickly without warping or cracking. Volume shrinkage per cent 10 . 1 Linear shrinkage per cent 2.5 Water of plasticity per cent 22.0 Shrinkage water per cent 5 . 5 Pore water per cent 16 . 5 Transverse strength tests of unburned clay Modulus of rupture without sand Lbs. per sq. in 78 'Number of Briquettes 15 Fineness test: Impossible to slake all the clay to obtain screen analysis. The clay is very fine grained; all that slakes passes the 200-mesh sieve. Slaking test _ minutes 6 a Tests made by Ceramic Engineering Department, LIniversity of Illinois, for the Illinois State Geological Survey. 26 KKFHA< TOKY (LAVS I X CALHOUN ■Burning test: Burning shrinkage Porosity Color Cone Linear Volume Hardness Per cent Per cen t Per cent 01 6.1 12.1 31.4 white not steel hard 2 6.6 18.6 30.4 cream not steel hard 3 cream not steel hard 4 8.5 23.5 26.1 cream steel hard 6 9.3 25.3 23.9 cream steel hard 8 9.7 26.4 22.1 cream steel hard 10 11.0 29.5 18.8 cream steel hard 12 11.8 31.3 16.8 gray steel hard 14 13.0 34.2 14.2 gray steel hard 16 13.6 35.5 12.3 gray steel hard Soluble sulfates None Warpage None Fusion (Deformation) test: P. C. E., Cone 33-34 (approximately 3173°-3200°F.) Suggested uses: The clay should be a valuable raw material for use in the manufacture of high-grade flint fireclay refractories. In refractoriness the clay is equal to the best of the Missouri smooth flint clays. The firing shrinkage of the clay is somewhat excessive and this would probably necessitate the use of a large amount of calcined clay. Sample O Outcrop in the SW. % SE. *4 SE. % sec. 8, T. 10 S., R. 2 W.« Kind of material No. 2 fireclay Reaction for carbonates Present Color Almost white Working property Fair; sticky Drying conduct Good Volume shrinkage per cciit 32.3 Linear shrinkage per cent 9.8 Water of plasticity per cent 33 . 5 Shrinkage water per cent 17 . 8 Pore water per cent 15.7 Transverse strength tests of unburned clay Modulus of rupture with 50 percent standard sand Lbs. per sq. in 406 Number of Briquettes 10 Modulus of rupture without sand Lbs. per sq. in 694 Number of Briquettes 10 a Test made by Ceramic Engineering Department, University of [llinois, for the Illinois State Geological Survey. AXD PIKE COUNTIES, ILLINOIS 27 Fineness test: Mesh Residue per cent Character of residue 10 0.5 Small lime pebbles 20 0.6 Small lime pebbles 48 0.8 Small lime pebbles 100 0.5 Sand and lime pebbles 200 0.5 Sand and lime pebbles Through 200 97.1 Burning test: Burning shrinkage Total Shrinkage Linear Porosity Per cent Cone Linear Volume Color Hardness Per cent Per cent • Per cent 2 10.0 27.1 19.8 8.8 light buff 4 11.1 29.7 20.9 3.7 light buff 6 11.7 31.1 21.7 0.6 buff 10 12.3 31.8 21.8 0.0 gray 12 10.9 29.3 20.7 0.5 gray (fused lime spots) 13 9.3 25.4 19.1 3.8 gray (fused lime spots) Oxidation conduct Easily oxidized Soluble sulfates None Fusion (Deformation) test: P.C.E., Cone 29 (approximately 2984° F.) Warpage Warps a little ; high shrinkage Suggested uses: Aside from disadvantage of high shrinkage the clay should be an excellent stoneware material, refractory bond clay, terra cotta and face brick clay. Firing range for zero absorption and constant shrinkage, cones 6 to 10 or 12, inclusive. Between cones S and 10 the color changes to gray. POSSIBILITIES OF DEVELOPMENT The occurrence of flint clay in DeGerlia Hollow may signify potential resources of this clay in the area although the outcrop itself is not neces- sarily of great economic importance. A careful search of the neighboring valleys revealed no other outcrops of flint clay but white plastic clays simi- lar to those associated with the flint clay were noted at two places in the NW. y 4 sec. 17, T. 10 N., R. 2 W., at elevations of 700 and 720 feet." Therefore the flint clay too may not be limited to the small gully in which it crops out, and additional deposits in the vicinity may be revealed by a general plan of prospecting similar to that outlined in connection with the Howell Hollow area (p. 22). As the clay is believed to occur in sinks, the extent of any one deposit can be roughly ascertained if the limestone rim of the sink can be outlined. It is recommended that the prospecting be con- 3 Rubey, W. W., personal communication. 28 REFRACTORY CLAYS IN CALHOUN centrated along the upper slopes of ridges having an elevation of more than r t'l~) feet, as the normal position of the clay is at an elevation of about 700 to 720 feet and it will probably not be found in place below an elevation of 665 feet. Inasmuch as the DeGerlia Hollow deposit, in part at least, has a thick overburden, the extent of the deposit and the thicknesses of the clays and overburden should be definitely determined before development is begun. ORIGIN OF CALHOUN COUNTY FLINT CLAYS An adequate understanding of the origin of any clay or other mineral deposit is essential for intelligent commercial development. Data bearing on the origin of the Calhoun County flint clays are so meager and fragmen- tary because of the limited exposures that any conclusions must be derived by inference rather than by direct observation. The flint clays in Missouri are commonly found in depressions which are interpreted as ancient sink holes, the walls of which are normally lined with more or less sandstone upon which the flint clays rest. Wheeler 4 ascribed the sandstone lining of the sinks and certain structural features of the clay itself to deposition in pre-Pennsylvanian sink holes that had de- veloped in underlying limestone formations, but McQueen"' has suggested that the clay and underlying sandstone originally were deposited as a hori- zontal series which later slumped into limestone sinks formed after the de- position of the sandstone and clay. It is further suggested that the sink holes offered excellent avenues for the descent of surface waters which leached and removed the silica and thereby increased the per cent of alumina in the clay. The Illinois flint clays appear to be a northeastward extension of the Missouri deposits, and so it is reasonable to assume that they possess many characteristics common to the Missouri deposits. They are thought to occur in sink holes, whose age is not definitely established, but which probably developed before the present drainage systems were formed, inasmuch as the narrow ridges upon which the sinks are now found are not the normal place for the development of sink holes. Above the flint clays and associated fireclays, no beds definitely of Pennsylvanian age have been found in Illinois. Instead there is usually a foot or two of chert gravel with a clay matrix, which has evidently been derived mostly from adjacent higher areas and is probably considerably younger than the clay on which it rests. Diaspore clays or burley flint clays are locally associated with the smooth flint clays in Missouri but are limited to the north central Ozark district of Missouri, except for one occurrence of burley clay in the northern part of Lincoln County, Missouri, immediately west of Calhoun County. 6 So 'Wheeler, )1. A., Clay Deposits, Missouri Geol. Survey, vol. 11, p. 202, 1S96. 6 5 McQueen, II. S., t'.eologic relations of the diaspore and flint clays >>! .Missouri, Bull. Amer. Cer. Soc, vol. 12, No. 10, p. 695, Oct. 1929. ' .McQueen, H. S., op. cit. p. 696. AND PIKE COUNTIES, ILLINOIS 29 far as is known there are no deposits of diaspore or burley clay in Illinois. The only suggestion of high alumina clays in Illinois was observed by Van Felt 7 in some of the pits in the so-called Cheltenham bed near White Hall, Greene County, where a discontinuous band of calcareous pisolitic nodules is found. These nodules, of which the largest is about 10 inches in diameter, contain small amounts of the mineral diaspore but are without commercial significance. Although the general field evidence does not point to the oc- currence of diaspore clay in Illinois, the possibility of its existence should not be overlooked. SOUTHERN CALHOUN COUNTY AREA 8 Location and Occurrence The southern Calhoun County area includes the uplands of that part of Calhoun County lying south of an east-west line through Beechville in sec. 33, T. 13 S., R. 2 W. A large portion of the area is underlain by Penn- sylvanian strata, which include thick shale beds and the underclay below the Golden Eagle (No. 2) coal, thought to be the equivalent of the Chelten- ham clays of Illinois and Missouri. Geology The general sequence of strata found in southern Calhoun County may be described briefly as follows : 9 Generalized geologic section of Pennsylvanian strata in Southern Calhoun County Thickness Unconformity Feet McLeansboro formation 12. Limestone, gray, weathers brown; dense, massive, fossili- ferous; forms a prominent ledge 5 + 11. Clay, calcareous, pale buff 15± 10. Limestone, dark gray, dense; massive below, thin bedded above; fossiliferous; somewhat conglomeratic 8± 28± Carbondale formation 9. Clay, calcareous, pale greenish-gray with thin carbonaceous zones at top and bottom; contains irregular masses of white, calcareous powder 4 to 12± 7 Van Pelt, J. R., personal communication. 8 The data on this area were obtained partly in cooperation with W. W. Rubey during the sampling of the non-metallic mineral deposits of the Brussels quadrangle and partly from the following bulletins: Parmelee, C. W., and Schroyer, C. R., Further Investigations of Illinois Fire Clays, Illinois State Geol. Survey Bull. 3SD, pp 81 and S2, 1921; and Weller, Stuart, Notes on the Geology of Southern Calhoun County, Illinois State Geol. Survey Bull. 4, pp. 229-233, 1907. 9 Rubey, W. W., Geologv and Mineral resources of the Hardin-Brussels quad- rangles, Illinois' Geol. Survey, Unpublished manuscript. 30 REFRACTORY ( LAYS IN CAiHOUK Thickness Feet 8. Limestone, light gray, fine grained, massive below, nodular above; somewhat conglomeratic; weathers to an irregular knobby surface and forms a prominent ledge 6± 7. Fireclay, pale gray to white, mottled with yellow, brown, red, maroon, and purple and with thin carbonaceous zone at top 3 — to 15 + 6. Shale and siltstone, noncalcareous, sandy, micaceous, greenish to buff-gray, brown and maroon, platy to mas- sive; grades laterally into very fine grained argillaceous sandstone 50± 5. Black laminated shale or very argillaceous coal; locally pyritic, fossiliferous, and with ferruginous nodules and layers of dense gray limestone less than 1 inch thick. . . .A few inches to 4— 4. Coal, contains a local parting of clay shale and ferruginous concretions near top A few inches to 3— 6'> to 90 Pottsville formation 3. Fireclay, gray to white, locally pyritic; contains con- cretionary masses of pisolitic or phosphatic limestone near top to 12 + 2. Clay, sandy; dark shale, and argillaceous sandstone; poorly exposed to 12 + 1. Sandstone, locally conglomeratic and cross-bedded to 20 + to 8J+ (com- monly 10 to 85 \ Unconformity The I Ynnsylvanian formations are usually best exposed in the valleys on the west side of the major northwest-southeast divide. The coal and its associated clays doubtless underlie a large part of the region and the over- lying shales also outcrop over a wide area, being especially common in the heads of the valleys. Ceramic Properties of Clays The underclay (bed No. 3, geologic section) below the Golden Eagle coal appears to be a refractory clay of good quality, as fire brick graded as St. Louis No. 1 were formerly made from it. Tests made on two samples, one taken from a pile of clay near the mine of the Golden Eagle plant where it had evidently been dug several years previously but appearing fresh and unweathered (Sample 1'), and the other obtained from an exposure in a gully in the NE. % SW. ]/ A SW. % sec. 3 1, T. L2 S., R. 2 W., near Beeeh- ville (Sample Q), indicate that the clay will probably be satisfactory for AND PIKE COUNTIES, ILLINOIS making light colored face brick, conduits, refractories and terra cotta, and as a refractory bond clay (Samples P and 0). The clays appear to be too refractory for making light weight, burned clay aggregate by processes now used commercially. Table 6. — Results of tests a on clay from pit of Thomas Brick Company near Golden Eagle, Southern Calhoun County Sample P Under elay of Golden Eagle Coal Clay, very hard, grayish colored; contains much finely divided pyrite. Upon the addition of a suitable amount of water it develops a good degree of plas- ticity but is sticky. It slakes very slowly. Water of plasticity per cent 34.4 Shrinkage water per cent 25.5 Pore water per cent 18.9 Modulus of rupture lbs. per sq. in. 165.7 With 50% standard sand — Modulus of rupture lbs. per sq. in. 124.6 Slaking test : hours 5 y 2 Screen test: Mesh Residue Per cent Character of residue 120 .150 200 .50 .09 .12 Pyrites, sand, clay, and organic material Mica and sand Pyrites, sand, clay, and organic material Drying shrinkage: Linear; wet length per cent 10.05 Linear; dry length per cent 11.6 Burning test: Cone Porosity Per cent Burning Shrinkage Per cent Color Remarks 2 10.0 6.1 5 5.2 6.0 tan Small black core 9 7.0 4.3 buff Black core, fine iron 12 5.0 5.0 buff exterior; blue- stoned spots 13 7.0 2.6 Plashed 15 5.5 2.8 buff; bluestoned Overburned Fusion test: Cone % deformed at cone 26 (approximately 2903°F.). The cone has a vesicular structure. Summary This clay has a medium low strength and a medium low bonding strength. The drying shrinkage is medium high. The effect of the small residue of finely divided pyrite becomes evident at the higher temperatures, especially in the fusion test. Washing the clay for some products will correct this. The poor a Parmalee, C. W., and Schroyer, C. R., Further investigations of Illinois fire clays: Illinois State Geoi. Survey, Bull. 38D, p. 81, 1921. 32 KKI'UACTOHY (l.AVS I.N ( A], HOC X oxidation conduct should be noted. The clay is on the border line between a non-refractory and a refractory material. The test piece has the appearance of having been overtired at cone 15. Suggested uses: Architectural terra cotta, face brick. Sample Q Vnderclay of Golden Eagle coal from gully in NE. % SW. % SW. Vx sec. 84, T. 12 8., R. 2 W. Kind of material No. 2 fireclay Reaction for carbonates Small amount present Color Light buff Working property Fair; sticky Drying conduct Good Volume shrinkage per cent Linear shrinkage per cent Water of plasticity per cen t Shrinkage water per cent Pore water per cent Transverse strength tests of unburned clay Modulus of rupture with 50 per cent standard sand Lbs. per sq. in Number of briquettes Modulus of rupture without sand Lbs. per sq. in Screen test: 29.4 8.9 27.7 15.4 12.:; 312 9 487 Mesh Residue per cent Character of residue 1U Trace Small lime pebbles 20 0.1 Small lime pebbles 48 0.1 Sandy 100 0.3 Sandy 200 1.1 Sandy Through 200 98.4 Burning test: Burning shrinkage Total Shrinkage Linear Porosity Per cent Color Cone Linear Volume Hardness Per cent Per cent Per cent 2 7.6 21.0 16.5 19.5 cream steel hard 4 7.9 21.8 16.8 17.4 cream steel hard 6 8.0 22.0 16.9 16.5 cream steel hard 8 8.4 23.2 17.3 14.2 slightly darker steel hard 10 9.1 24.8 18.0 11.4 slightly darker steel hard 12 10.0 27.0 1S.9 5.9 gray steel hard 13 10.4 28.0 19.3 1.2 rusty steel hard (fused lime spots) AMI PIKE COUNTIES, ILLINOIS Oxidation conduct Easily oxidized Total soluble salts Vanadium Fusion (Deformation) Test: P. C. E., Cone 30 (Approximately 3002° F). Warpage None Suggested uses: Light colored face brick, conduit, refractories, refractory bond clay, terra cotta, quarry tile, roofing tile. Remarks: Good burning range — cones 4-8 inclusive for light color. The shales (bed Xo. 6, geologic section) overlying the coal formerly furnished raw material for the manufacture of pressed brick. Of the 35 feet of these shales exposed in the old pit the lower 12 to 15 feet is green- ish gray and the upper 50 feet is maroon or mottled maroon and green. Tests on sample R. taken from the 35 feet of outcropping shales, show that it is suited for the manufacture of face brick, paving brick, roofing tile, and probably light weight, burned clay aggregate. Table 6. — Continued Sample R Maroon shale above Golden Eagle coal Kind of material Shale Reaction for carbonates Present Reaction for pyrites None Color Light chocolate brown Working property Not very plastic Conduct when flowing through a die Satisfactory Drying conduct Small amount of scum. No warping Volume shrinkage per cent 20.1 Linear shrinkage per cent 6.3 Water of plasticity per cent 26.2 Shrinkage water ■ per cent 10.8 Pore water per een t 15.4 Transverse strength of unburned clay Modulus of rupture with 50 per cent standard sand Lbs. per sq. in 289 Number of Briquettes 12 Burning test: Cone 05 03 1 2 4 Burning shrinkage Linear Per cent Volume Per cent 8.3 10.7 10.6 10.4 8.6 22.8 28.7 28.5 28.1 23.6 Total Shrinkage Linear Per cent 14.6 17.0 16.9 16.7 15.9 Porosity Per cent 12.3 1.1 0.8 0.4 0.5 Colo ' Hard ness light red steel hard reddish br awn steel hard good dark red steel hard good dark red steel hard very dark red steel hard Oxidation conduct Oxidizes easily at low temperature Warpage None Soluble sulfates Trace 34 REFRACTOR* CI.AYS IN CALIKIIN Suggested uses: The shale burns to a good color and has an excellent firing range — cones 03 to 2 inclusive — and should be valuable for brick manufac- ture, paving brick, quarry tile and roofing tile. Sample R Chemical analysis Per cent Lime (CaO) 1.05 Magnesia ( MgO ) 2.04 Silica (Si0 2 ) 58.04 Alumina ( Al.,0, ) 24.40 Iron oxide (Fe.O..) 6.66 Sulfuric anhydride (SO,) 0.86 Loss on ignition 7.61 100.66 Tests made on a sample taken from the lower 4 feet of a 5-foot bed of non-bedded clay (Bed No. 7, geologic section) above the green and maroon shale in the Golden Eagle pit indicate that it is moderately refractory and could be used for light colored brick, terra cotta, quarry tile, and roofing tile. The clay is probably too refractory to be well adapted for making light weight, burned clay aggregate. (Sample S.) Table 6 — Continued Sample S Clay above maroon and green shale Kind of material Clay Reaction for pyrites None Color Cream Working property Good Drying conduct Satisfactory Volume shrinkage per cent 21 A Linear shrinkage per cent 9.3 Water of Plasticity per cent 21 A Shrinkage water per cent 15.8 Pore water per cent 11.6 Transverse strength tests of unburned clay — Not enough clay to test. Screen test: Mesh Residue Per cent Character of residue 10 0.0 0.0 0.1 Trace 3.6 96.3 20 48 100 Sandy 200 Through 200 Sandy, micaceous AND PIKE COUNTIES, ILLINOIS 35 Burning test: Burning shrinkage Total Shrinkage Linear Per cent Porosity Per cent Color Cone Linear Per cent Volume Per cent Hardness 03 6.4 17.9 15.7 2.0 light tan steel hard 01 6.4 18.1 15.7 0.6 tan steel hard 2 6.6 18.4 15.9 0.5 tan steel hard 4 6.6 18.5 15.9 0.8 grayish tan steel hard 8 6.2 17.4 15.5 1.7 grayish tan steel hard 10 Flat Oxidation conduct Easily oxidized Soluble sulfates None Fusion (Deformation) Test: P. C. E., Cone 15 (approximately 2615° F. ) Warpage None Suggested uses: The clay has a long firing range and could be used for light colored brick, terra cotta, quarry tile, and roofing tile. Overburned at cone 8. Possibilities of Development The fact that three clays of different degrees of refractoriness and of different character are available in southern Calhoun County, locally all three at one place, makes this region one of particular interest to the clay products manufacturer desiring diversified raw materials and products. Although none of the clay is being utilized at the present time, its economic import- ance is evident from the fact that the Thomas Brick and Clay Company formerly operated a plant with a capacity of 25,000 to 30,000 bricks per day near the center of sec. 1, T. 14 S., R. 2 \Y., about \ l / 2 miles southeast of Golden Eagle, and shipped large quantities of No. 1 fire brick to St. Louis. The company mined about 5 feet of the underclay below the Golden Eagle coal and also mined the coal. The clay below the mined portion was not utilized because it contained nodular masses of limestone full of pyrite. The green and yellow-green shale above the coal was used for pressed brick. Calhoun County is handicapped by the lack of railroads. The Thomas Brick and Clay Company loaded their bricks in railroad cars which were ferried to connections at Peruque, Missouri, or Grafton, Illinois. However, the increasing interest in waterway transportation of bulky materials en- hances the potential value of mineral deposits located near navigable streams. In the case of the clays in southern Calhoun County, they or the products made from them could be shipped on Mississippi River which is cut- ting along its east bank so that dee]) water and numerous favorable sites for dock loading platforms are available on the west and south sides of the area. Any clav mine or pit should be located so as to take advantage of 36 ISICI K.UTORY (LAYS IX CALHOUN these natural facilities. Topographic maps 10 will assist in the selection of a plant or pit site. ' Ipen-pit mining, necessitating relatively large scale development, may be feasible at a number of places where it is possible to use the shale over- lying the underclay and coal. In smaller operations subsurface mining will probably he more advisable for working the coal and underclay. Commer- cial development of the underclay of the Golden Eagle coal appears to offer most favorable economic conditions, as the coal can he. mined with the clay and would furnish perhaps half the fuel necessary to burn the products. The underclay of the Golden Eagle coal and its associated shale strata appear to he relatively constant in character and distribution, so that less test drilling is needed to determine their quality and extent than in the case of more variable deposits. However, tests should he made to make sure that no unexpected changes occur in the character and thickness of the clay or shale and to prove the presence of a sizeable body of raw material before operations are begun. PITTSFIELD AREA Location and Occurrence In former years clay for the manufacture of brick and tile and for us< with other clays in making pottery has been dug at a number of places in the vicinity of Pittsfield. One of the most extensively worked deposits was in the low bluffs on the south side of Ray Creek in sec. 12, T. 5 S.. R. 4 \Y.. about two miles north of Pittsfield. The outcrop is now covered but the following geologic section is reported to have been exposed when clay was being dug: Feet Inches Loess and drift 0—20 Gravel 0—10 ( lay, white 2± Clay, gray (Sample T) 12± Borings in the immediate vicinity of this exposure show that the clay underlies a tract several acres in extent, and the topography suggests that large areas to the south and to the east may be also underlain by the clay. 13 Other outcrops of clay are reported about two miles south of Pittsfield 12 and about :>'_. miles south of Pittsfield. Two to five feet of white, highly plastic clay, containing angular chert fragments, overlain by six to fourteen feet of stream silt, loess, and drift 10 Available for 1" cents each at Illinois state Geological Survey, Urnana, Illinois. "i- at I'. S. Geological Survey, Washington, E). C. 11 Parmelee, C. W.. and Schroyer, C. R., Further investigations of Illinois I ''lays. Illinois Stale Geol. Survey Bull. 38D, p. :•:., 1921. 12 Lines, E. I!.. Pennsylvanian Fire Clays of Illinois. Illinois state Geol. Survey. Bull. 30, l'. 69, 1917. AND PIKE COUNTIES, ILLINOIS 37 is exposed along Honey Creek near the center of the north half of sec. 26, T. 5 S., R. 4 W., on the outskirts of Pittsfield. Sample U was taken from this exposure. R.3 W. Vt I Mile Fig. 5. Topographic map of Pittsfield and vicinity. (Part of Pittsfield quadrangle map.) Geology The clay of the Pittsfield area is probably a part of the Cheltenham member of the Pennsylvanian system, and appears to be roughly the strati- 38 REFRACTORY CLAYS IN CAMIOIN graphic equivalent of the Calhoun County clays. No data are available to determine whether or not the clays of the Pittsfield area occur in ancient sinks, although it is known that a few miles farther east Pennsylvanian sedi- ments do occur in this fashion. Ceramic Properties Hie results of tests on two samples of clay from the Pittsfield area indicate that the clay is suited for the manufacture of building brick, stove tile, stoneware, architectural terra cotta, sanitary ware, quarry tile, and for use as a plastic bond for refractories (Samples T and U). Because they are refractory, the clays are not well adapted for use in making light weight. burned clay aggregate by processes now used commercially. Table 7. — Results of tests on clay in the Pittsfield area Sample T Two miles north of Pittsfield « This is a soft clay, colored yellow to dark brown. A fair degree of plasticity may be developed. Water of plasticity per cent 27 Shrinkage water per cent 13.5 Pore water per cent 13.5 Modulus of rupture lbs. per sq. in. 414.5 Slaking test, average minutes 11 Screen test: Mesh Residue Per cent Character of residue 20 40 60 80 120 200 0.08 Trace Trace Trace 0.79 1.32 Rock particles and organic matter White sand and rootlets White sand and rootlets Drying shrinkage: Linear; dry length per cent 8.2 Volume Per cent 24.5 (i Farmelee, C. W., and Schrover, C. R., Further Investigations c,f Illinois Fire Clays, Illinois Geol. Survey Bull. 3SD, p. 101, 1921. AND PIKE COUNTIES, ILLINOIS 39 Burning test: Cone Burning shrinkage Per cent Porosity Per cent Color Remarks 02 4.9 5.1 17 14 cream cream 2 3 5.8 12 medium cream Smooth fracture; fine iron specks (?); none on another trial piece. 6 6.2 6 medium cream Smooth fracture; fine iron specks (?); none on another trial piece. Somewhat conchoidal fracture. 9 6.3 1.2 stoneware gray Vitreous. 12 5.0 1.0 gray white Fine veining of iron stain; good color. 13 4.5 1.6 gray white gray white 15 4.5 3.8 Fine iron spots. Fusion test: Deformed at cone 29 (approximately 2984° F.) Summary The sample is a clay of medium high strength which has a medium drying shrinkage. The total shrinkage at cone 9 is medium high. Vitrification is prac- tically complete between cones 6 and 9. There are some indications of overturn- ing at cone 15. It is a refractory clay. Suggested uses: Stoneware, architectural terra cotta, sanitary ware, a plastic bond clay for refractories. Sample U Outcrop along Honey Creek N. y 2 sec. 26, T. 5 8.. R. k W.a Kind of material Clay Drying conduct Good Volume drying shrinkage per cent 20.20 Linear drying shrinkage per cent 7.24 Water of plasticity ' per cent 27.00 Bonding strength — Modulus of rupture lbs. per sg. in. 357.8 Bulk specific gravity 1.89 Screen test: Residue Mesh Per Cent 28 0.9 48 3.2 65 1.5 100 0.7 200 1.1 o Test made by Ceramic Engineering Department, University of Illinois, for the Illinois State Geological Survey. 40 BEFBACTORY (LAYS IN C'AI.HOl'X Burning test: Burning shrinkage Porosity Per cent Color Cone Volume Linear Fracture Per cent Per cent 02 11.79 4.10 19.25 salmon pink granular 2 11.95 4.15 20.04 tan granular 3 14.45 5.07 13.73 tan granular 6 13.88 4.86 14.00 tan granular 7% 18.38 3.95 13.84 light tan granular 10 19.38 6.93 9.53 tan granular 11 21.21 7.64 9.25 bluestoned granular Fusion (Deformation) test: P.C.E., Cone 26 (approximately 2903° F.) Oxidizing conduct: medium S PM MARY Drying shrinkage, medium; bonding strength, medium; vitrification incom- plete at cone 11; shrinkage at cone 11 is medium low. It is nonrefractory. Suggested uses: Building brick, stove tile, possibly flue linings, architectural terra cotta, sanitary ware, quarry tile, and roofing tile. Possibilities of Development The data suggest that extensive areas in the vicinity of Pittsfield are underlain by clays which appear to be potential sources of good ceramic materials, but the distribution and character of the deposits are not well known. The topography of the Pittsfield area with its relatively broad up- land flats is generally favorable to development of large pits, but all of the area except that portion lying north of Pittsfield, which is served by a branch line of the Wabash Railroad, is without railroad transportation. Drilling and thorough testing to ascertain the extent and character of the deposit should be made before extensive exploitation of any given deposit is under- taken. SIXMILE CREEK AREA Location and Occurrence A test pit dug at the head of a north-south ravine in the range of hills lying east of Sixmile Creek in the SE. corner of the NW. )\ NE. J4 sec. 5, T. 7 S., R. 4 W., about 2 l /> miles north of Pleasant Hill, shows the fol- lowing geologic section: Thickness Feet 4. Loess 6+ 3. Gravel, chert in a clay matrix 1 2. Clay, red 1— 3 1. Clay, mostly yellow but mottled with gray •■ . • • 5% Covered AND PIKE COUNTIES, ILLINOIS 41 The pit is about 25 feet below the top of the ridge and the exposed clay is obviously contaminated with overlying material. Where fresh it will prob- ably be found to be gray, without the yellow iron-stain which has evidently been introduced from the overlying sediments. The red clay and overlying chert gravel are similar to the section found above the clay in the Howell Hollow area in Calhoun County, and the general character of the yellow clay also resembles the clays of that area. The bedrock core of the hill is Burlington limestone. R.4 w. i Mile Fig. 6. Topographic map of Sixmile Creek area, showing loca- tion of prospect pit. (Part of Nebo quadrangle map.) Ceramic Properties The results of tests on a sample of clay (Table 8, Sample V) taken from the test pit show that the clay is not of as high quality as that in the Howell Hollow area, which might be expected, as the sample was more or less contaminated, but they suggest that it may compare favorably and in- dicate certainly that the Sixmile Creek area is worthy of further prospecting. 42 HKKHACTORY CLAYS IN CALHOUN Taisle 8. — Results of tests on clay from Sixmile Creek area Sample V Test Pit, NE. V4 sec. 5, T. 6 S., R. 4 W.« Kind of material Clay Reaction for carbonates Present Reaction for pyrites None Color Dark buff Hardness Medium Working property Good Conduct when flowing through a die Satisfactory Drying conduct Scums a little in drying. No warping or cracking Volume shrinkage per cent 32.0 Linear shrinkage per cent 9.7 Water of plasticity "per cent 27.8 Shrinkage water per cent 16.2 Pore water per cent 11.6 Transverse strength tests of unburned clay Modulus of rupture with 50 per cent standard sand Lbs. per sq. in 259 Number of briquettes 13 Modulus of rupture without sand Lbs. per sq. in ' 440 Number of briquettes 13 Fineness test: Mesh Residue Per cent Character of residue 10 20 48 100 200 Through 200 0.1 0.1 0.2 0.6 5.8 93.2 Pebbly Pebbly Micaceous, sandy Micaceous, sandy Micaceous, sandy Burning test: Burning shrinkage Total Shrinkage Linear Porosity Per cent Color Cone Linear Volume Hardness Per cent Per cent Per cent 2 4.7 13.4 14.4 16.7 very light tan almost steel hard steel hard 4 5.7 16.1 15.4 12.5 buff steel hard 6 6.1 17.3 15.8 11.4 tan steel hard 8 6.3 17.8 16.0 9.7 tan steel hard 10 7.1 19.7 16.8 5.9 gray steel hard 12 7.5 20.9 17.2 4.1 gray steel hard 13 4.5 12.8 14.2 11.5 gray (fused lime spots) it Tests made by Ceramic Engineering Department, University of Illinois, for Illi- nois State Geological Survey. AND TIKE COUNTIES, ILLINOIS 43 Oxidation conduct Easily oxidized Soluble sulfates Present — small amount Warpage None Fusion (Deformation) Test: P.C.E., cone 23-26 (approximately 2876° — 2903°F.). Suggested uses: Light colored brick; flue linings; conduit; terra cotta; stone- ware. Remarks: Good burning range, cones 4-8 inclusive; overburned above cone 12. Possibilities of Development The Sixmile Creek exposure in itself does not demonstrate the exist- ence of a commercially valuable deposit of clay in the area, but it encour- ages prospecting to ascertain if this is so. It suggests further that additional clay deposits may be found in favorable places between the Howell Hollow area in Calhoun County and the Sixmile Creek area. In searching for clays in this region, prospecting would probably be most advantageous on the higher hills of the region, particularly those having an elevation of 725 feet or more. Test borings are recommended especially in the central portions of the ridges. Exploratory work along the sides of the hills is most likely to reveal clay at elevations above 665 feet. R'S" IBRARY BINDERS 507 3. GoodwtB Urbana,IlL