(r^sux Sujujuu 
 
 STATE OF ILLINOIS 
 
 WILLIAM G. STRATTON, Governor 
 
 DEPARTMENT OF REGISTRATION AND EDUCATION 
 
 VERA M. BINKS, Director 
 
 Lower Pennsylvanian 
 CLAY RESOURCES OF 
 KNOX COUNTY, ILLINOIS 
 
 Walter E. Parham 
 
 DIVISION OF THE 
 
 ILLINOIS STATE GEOLOGICAL SURVEY 
 
 JOHN C. FRYE, Chief URBANA 
 
 CIRCULAR 302 
 
 1960 
 
 ILLINOIS GEOLOGICAL 
 SURVEY LIBRARY 
 
 OCT £4 1960 - 
 
lUUNOtSSTAjTf 
 
 W»8 1 ^ 0000* 
 
Illinois State Geological Survey Circular 302 
 19 p., 1 fig., 39 tables, 1960 
 
Digitized by the Internet Archive 
 
 in 2012 with funding from 
 
 University of Illinois Urbana-Champaign 
 
 http://archive.org/details/lowerpennsylvani302parh 
 
LOWER PENNSYLVANIAN CLAY RESOURCES 
 OF KNOX COUNTY, ILLINOIS 
 
 Walter E. Parham 
 
 ABSTRACT 
 
 To determine the nature and uses of possible light-burning 
 clay deposits of Knox County, Illinois, about 40 samples of the under- 
 clays below the Colchester (No. 2) Coal were collected and tested. 
 
 Laboratory tests were made to determine the linear drying and 
 firing shrinkage, water of plasticity, firing color, refractoriness, and 
 bonding properties of the clay. The thickness of the clay, its over- 
 burden, and types of associated sediments were recorded from field 
 observations . 
 
 The southern part of Knox County is the best area for clay pros- 
 pecting. The thicker and lighter burning clays come from the south- 
 west part of the county. 
 
 INTRODUCTION 
 
 Knox County, with Galesburg as its largest city, is in western Illinois be- 
 tween the Mississippi and Illinois Rivers (fig. 1). As the land surface is for the 
 most part covered by Pleistocene glacial deposits, exposures of older rocks occur 
 mainly along the stream valleys. Some of the bedrock exposures contain various 
 clays (underclays) that occur below the Colchester (No. 2 ) Coal and lower coals. 
 Underclays higher in the stratigraphic section than the No. 2 Coal are not consid- 
 ered in this report. 
 
 In general, the rocks of Pennsylvanian age in Knox County slope gently to 
 the east or southeast. The older Pennsylvanian rocks are exposed in the south- 
 west portion of Knox County, and the samples were obtained from that general area. 
 A more complete account of the geology of this region is given by Green (1870) . 
 
 The physical properties and burning characteristics of the underclays vary 
 widely from one area to another in Illinois. This is one of a series of reports issued 
 by the Illinois State Geological Survey on light-burning clay resources of Illinois 
 counties, designed to aid in the selection of clays for specific uses. Circular 277 
 dealt with the clay resources of LaSalle County. 
 
 REPORT OF TESTS 
 
 This report includes locations of existing clay deposits in Knox County, 
 their thickness, overburden, type of underlying and overlying sediment, possible 
 uses, and the results of tests on the physical properties of the clays. The test 
 results include the drying and firing shrinkage of the clay, water of plasticity, 
 fired colors, and bonding properties. 
 
 [3] 
 
4 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 302 
 
 Extrusion and Firing of Test Bars 
 
 Each sample of clay was dried and crushed to particles approximately one- 
 fourth inch or less in diameter. The sample was then mixed with enough water to 
 develop plasticity and extruded into three individual test bars, each 1 by 1 by 6 
 inches. The bars were air-dried for at least two days, then measured to determine 
 the percentage of drying shrinkage of the clay. The first brick was fired at 1832°F, 
 the second at 2012°F, and the third at 2200°F. After each firing, the test bars 
 were measured to determine the percentage of firing shrinkage. 
 
 
 
 
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 1533 
 
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 1536 
 
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 1555 
 
 
 
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 1 
 
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 353 
 
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 1552 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 RIE R 2 E R3E R4E 
 
 Fig. 1. - Map of portion of Knox County showing locations of outcrops sampled. 
 
 Water of Plasticity 
 
 The water of plasticity was determined for each sample at the time the test 
 bars were extruded. Water of plasticity is that amount of water that must be added 
 to a clay sample in order to develop plasticity. In general, the greater the water 
 of plasticity, the greater the shrinkage during drying and firing of a given clay. 
 
CLAY RESOURCES OF KNOX COUNTY 5 
 
 Color of Fired Test Bars 
 
 All of the clay samples in this study were obtained from outcrops, and it is 
 probable that weathering has altered the burning color of the clay. For a better in- 
 dication of true burning color it would be necessary to obtain unweathered samples 
 of the clay from drill holes near the area in question. A weathered, light-burning 
 clay generally burns darker than unweathered clay from the same deposit, owing to 
 the oxidation of pyrite in the clay and to the fine dissemination of iron throughout 
 the clay deposit. 
 
 High-Temperature Properties 
 
 The mineral analyses by X-ray, the colors of the fired test bars, and past 
 experience indicate that none of the samples from Knox County studied in this re- 
 port would withstand temperatures of PCE (pyrometric cone equivalent) 28 or higher. 
 
 Bonding Tests 
 
 Because underclays are sometimes used as a bonding clay for foundry sands, 
 bonding tests were run on all the samples. The clays were first ground in a disc 
 grinder. A 2000-gram mixture of 92 percent bonding sand and 8 percent clay was 
 made and mixed dry for two minutes in a sand muller. Water was then added to the 
 mixture in the muller and three minutes of wet mixing followed. The wet mixtures 
 were placed in sealed jars and allowed to set overnight in order to give the water 
 enough time to mix thoroughly with the clay. Mixtures were made with various 
 amounts of water — 30 ml, 35 ml, and 45 ml. For some samples of the stronger 
 bonding clays, additional mixtures with 55 ml of water were made. 
 
 The tests were run in a manner described in the Foundry Sand Handbook 
 (American Foundrymen's Society, 1952). Listed in the following tables under 
 "Bonding properties" are figures representing the green compression strength in 
 pounds per square inch (GCS psi) . This is the maximum strength developed by the 
 clay at its optimum water content. 
 
 Results of all tests made appear on the following pages in tabular form. 
 
RESULTS OF TESTS 
 
 SAMPLE 1533 
 NEp NW? SE5- sec. 4, T. 11 
 
 R. 2 E. 
 
 Thickness : 
 
 Ft. 
 
 Overburden 
 
 
 Overlying rocks 
 
 50 
 
 No. 2 Coal 
 
 1-2 
 
 Underclay (sample 1533) 
 
 i-1 
 
 Sandy nodules and 
 
 
 calcareous shale 
 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 In. 
 
 Extrusion properties Good 
 
 Water of plasticity, percent 20.0 
 Linear drying shrinkage, percent 6.0 
 
 1832°F 
 3.0 
 9.0 
 Brick red 
 
 2012°F 
 3.0 
 9.0 
 Brick red 
 
 Surface texture of fired test bar: Bloating started at 2012°F. 
 Bonding properties: 4.50 (GCS psi)| 1.70 
 Possible uses: Flower pots. 
 
 [ optimum H_0). 
 
 2200°F 
 
 SAMPLE 1534 
 NEp SWi SVfcf sec. 3, T. 11 N., R. 2 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 40 
 
 Coaly streak s 
 
 Underclay (sample 1534) 1+ 
 
 Base covered 
 
 Firing temperature 1832°F 
 
 Linear firing shrinkage, percent 0.0 
 Total linear shrinkage, percent 4.0 
 
 Fired color Yellow-brown 
 
 Extrusion properties Very poor 
 Water of plasticity, percent 20.0 
 Linear drying shrinkage, percent 4.0 
 
 2012°F 
 0.0 
 4.0 
 Tan 
 
 Surface texture of fired test bar: Bloating started at 1832°F. 
 Bonding properties: 8.65 (GCS psi); 2.10 (optimum H~0). 
 Possible uses: Bonding clay, lightweight aggregate. 
 
 2200 °F 
 
 SAMPLE 1535 
 NWi NWi SEi sec. 4, T. 11 N. , R. 2 E. 
 
 1/8 
 
 Extrusion properties Good 
 
 Water of plasticity, percent 20.5 
 Linear drying shrinkage, percent 4.0 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 40 
 
 Coaly streak 
 Underclay (sample 1535) 4-5 
 Green clay band 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 4.08 (GCS psi); 1.80 (optimum H„0) 
 Possible uses: Lightweight aggregate, structural clay products, sewer 
 pipe, drain tile, pottery, flower pots. 
 
 1832°F 
 
 2012°F 
 
 2200 
 
 2.5 
 
 4.5 
 
 6.5 
 
 6.5 
 
 8.5 
 
 10.5 
 
 Sa lmon 
 
 Brick red 
 
 Tan 
 
CLAY RESOURCES OF KNOX COUNTY 
 
 SAMPLE 1536 
 SWi SW5- SEf sec. 28, T. 10 N., R. 4 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 15 
 
 Coal 5 
 
 Underclay (sample 1536) 2 + 
 
 Base covered 
 
 Firing temperature 1832°F 
 
 Linear firing shrinkage, percent 4.5 
 
 Total linear shrinkage, percent 10.5 
 
 Fired color Brick red 
 
 Extrusion properties Good 
 
 Water of plasticity, percent 26.0 
 Linear drying shrinkage, percent 6.0 
 
 2012°F 
 +3.0 
 3.0 
 Brick red 
 
 2200°F 
 
 Surface texture of fired test bar: Bloating started at 2012°F. 
 Bonding properties: 10.3 (GCS psi); 2.6 (optimum H2O) . 
 Possible uses: Bonding clay, lightweight aggregate. 
 
 SAMPLE 1537 
 NWi NE£ SH? sec. 4, T. 11 N. 
 
 R. 2 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 
 Shale (sample 1537) 
 Base covered 
 
 20 
 25+ 
 
 Extrusion properties Poor 
 
 Water of plasticity, percent 22.0 
 Linear drying shrinkage, percent 4.0 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 1832°F 
 3.0 
 7.0 
 Red -brown 
 
 2012°F 
 8.5 
 12.5 
 Brick red 
 
 2200 °F 
 
 5.5 
 
 9.5 
 
 Brick red 
 
 Surface texture of fired test bar: Has rough edges. Bloating started at 2200°F. 
 Bonding properties: 4.65 (GCS psi); 1.75 (optimum H2O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 SAMPLE 1538 
 SWi SWi NWi sec. 27, T. 10 N. , R. 2 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 25 
 
 No. 2 Coal 2+ 
 
 Underclay (sample 1538) 5^—6 
 
 Sandstone 
 
 Extrusion properties Poor 
 
 Water of plasticity, percent 20.0 
 Linear drying shrinkage, percent 4.0 
 
 Firing temperature 1832°F 
 
 Linear firing shrinkage, percent 1.5 
 
 Total linear shrinkage, percent 5.5 
 
 Fired color Salmon 
 
 2012°F 
 
 7.0 
 
 11.0 
 
 Brick red 
 
 2200 °F 
 
 0.0 
 
 4.0 
 
 Brick red 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 4.60 (GCS psi); 1.75 (optimum H2O) . 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 302 
 
 SAMPLE 1539 
 NWi NWi NWi sec. 33, T. 10 N. , R. 2 E. 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 25 
 
 No. 2 Coal 2 + 
 
 Underclay (sample 1539) 4 
 Sandstone 
 
 Extrusion properties Fair 
 
 Water of plasticity, percent 21.0 
 Linear drying shrinkage, percent 4.5 
 
 Firing temperature 1832°F 
 Linear firing shrinkage, percent 1.5 
 Total linear shrinkage, percent 6.0 
 
 Fired color Salmon 
 
 2012°F 
 
 6.5 
 11.0 
 
 Brick red 
 
 2200 °F 
 8.0 
 12.5 
 
 Brick red 
 
 Surface texture of fired test bar: Edges slightly rough at 2200°F. 
 Bonding properties: 4.25 (GCS psi); 1.62 (optimum H2O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 SAMPLE 1540 
 NEi NWi SWj sec. 10, T. 9 N. , R. 2 E. 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 15 
 
 No. 2 Coal 1 4 
 
 Underclay (sample 1540) 5 
 Sandstone 
 
 Extrusion properties Poor 
 
 Water of plasticity, percent 21.0 
 Linear drying shrinkage, percent 4.0 
 
 2012°F 
 
 2200° 
 
 6.5 
 
 7.0 
 
 10.5 
 
 11.0 
 
 Salmon 
 
 Brown 
 
 Firing temperature 1832°F 
 Linear firing shrinkage, percent 1.5 
 Total linear shrinkage, percent 5.5 
 
 Fired color Salmon 
 
 Surface texture of fired test bar: Has rough edges at all firing temperatures. 
 Bonding properties: 5.10 (GCS psi); 2.10 (optimum H2O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 SAMPLE 1541 
 NEi NEi NEi sec. 17, T. 9 N., R. 2 E. 
 
 Extrusion properties Poor 
 
 Water of plasticity, percent 17.0 
 Linear drying shrinkage, percent 3.5 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 40 
 
 Coal 2+ 
 
 Underclay (sample 1541 )( exposed ) 2 
 Sandy shale 
 
 Firing temperature 1832°F 
 
 Linear firing shrinkage, percent 0.5 
 
 Total linear shrinkage, percent 4.0 
 Fired color Pink 
 
 Surface texture of fired test bar: Bloating started at 2200°F 
 
 at 2012°F. 
 Bonding properties: 3.90 (GCS psi); 1.45 (optimum H2O 
 Possible uses: Lightweight aggregate, structural clay products, 
 
 drain tile, pottery, flower pots. 
 
 2012°F 
 
 
 
 2200 °F 
 
 5.0 
 
 
 
 2.0 
 
 8.5 
 
 
 
 5.5 
 
 Sa lmon 
 
 
 
 Tan 
 
 00°F. 
 
 Surface 
 
 scum 
 
 ducts, 
 
 sewer 
 
 pipe, 
 
2012°F 
 
 2200 °F 
 
 5.0 
 
 5.5 
 
 10.0 
 
 10.5 
 
 Salmon 
 
 Tan 
 
 CLAY RESOURCES OF KNOX COUNTY 9 
 
 SAMPLE 1542 
 SWi SW£ SE? sec. 5, T. 9 N. , R. 2 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 40 Extrusion properties Good 
 
 Coal li" Water of plasticity, percent 17.5 
 
 Underclay (sample 1542) 2?- Linear drying shrinkage, percent 5.0 
 
 Sandy shale 
 
 Firing temperature 1832°F 
 Linear firing shrinkage, percent 1.0 
 Total linear shrinkage, percent 6.0 
 
 Fired color Salmon 
 
 Surface texture of fired test bar: Normal. 
 Bonding properties: 4.41 (GCS psi); 1.50 (optimum H2O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 SAMPLE 1543 
 SWi NE£ NEi sec. 8, T. 9 N., R. 2 E. 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 
 
 Coal 
 Underclay (sample 1543) 
 Sandstone 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 Surface texture of fired test bar: Has slightly rough edges. Bloating started 
 
 at 2200 °F. 
 Bonding properties: 5.82 (GCS psi); 2.03 (optimum H2O). 
 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 SAMPLE 1544 
 SW? NEj NE£ sec. 8, T. 9 N. , R. 2 E. 
 
 55 
 
 Extrusion pr 
 
 operties 
 
 
 Fair 
 
 ii 
 
 Water 
 
 of pla 
 
 sticity, percent 
 
 23.0 
 
 4 
 
 Linear 
 
 dryin 
 
 g shrinkage, 
 
 perc 
 
 ;ent 4.0 
 
 
 1832°F 
 
 
 2012°F 
 
 
 2200°F 
 
 it 
 
 2.5 
 
 
 8.5 
 
 
 8.5 
 
 
 6.5 
 
 
 12.5 
 
 
 12.5 
 
 
 Pink 
 
 
 Brick red 
 
 
 Brick red 
 
 Thickness : 
 
 Ft. 
 
 In. 
 
 Overburden 
 
 
 
 
 Overlying rocks 
 
 
 52 
 
 Extrusion properties Fair 
 
 Coal 
 
 
 ii 
 
 Water of plasticity, percent 31.5 
 
 Underclay (sample 1544) 
 
 
 2 
 
 Linear drying shrinkage, percent 5.5 
 
 Coal 
 
 
 
 1* 
 
 Firing temperature 
 
 
 
 1832°F 2012°F 2200°F 
 
 Linear firing shrinkage, 
 
 percent 
 
 7.5 11.5 0.5 
 
 Total linear shrinkage, 
 
 percent 
 
 
 13.0 17.0 6.0 
 
 Fired color 
 
 
 
 Brick red Brick red Brick red 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 4.27 (GCS psi); 2.07 (optimum H2O) . 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
10 
 
 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 302 
 
 SAMPLE 1545 
 Sw£ NEi NEt sec. 8, T. 9 N. , R. 2 E. 
 
 Thickness : 
 
 Ft. In. 
 
 Overburden 
 
 
 
 
 
 Overlying rocks 
 
 
 
 47 
 
 Extrusion properties Fair 
 
 Coal 
 
 
 
 
 2 Water of plasticity, percent 20.0 
 
 Underclay (sample 1545) 
 
 
 
 3i-4 
 
 Linear drying shrinkage, percent 6.5 
 
 Coal 
 
 
 
 1* 
 
 
 Firing temperature 
 
 
 
 
 1832°F 2012°F 2200°F 
 
 Linear firing shrinkage, 
 
 , percent 
 
 
 1.0 5.0 +2.0 
 
 Total linear shrinkage, 
 
 percent 
 
 
 7.5 11.5 4.5 
 
 Fired color 
 
 
 
 
 Red-brown Brick red Brick red 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 4.95 (GCS psi); 1.90 (optimum hUO). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 SAMPLE 1546 
 SWi NE? NEr sec. 8, T. 9 N. , R. 2 E. 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 32 
 
 No. 2 Coal l£ 
 
 Underclay (sample 1546) 5 
 Sandstone 
 
 Extrusion properties Good 
 
 Water of plasticity, percent 18.0 
 Linear drying shrinkage, percent 5.5 
 
 Firing temperature 1832°F 
 Linear firing shrinkage, percent 0.5 
 Total linear shrinkage, percent 6.0 
 
 Fired color Salmon 
 
 2012°F 
 4.5 
 10.0 
 Brick red 
 
 2200°F 
 4.0 
 9.5 
 Brick red 
 
 Surface texture of fired test bar: Slight bloating started at 2200°F. 
 Bonding properties: 4.56 (GCS psi); 1.80 (optimum h^O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 SAMPLE 1547 
 SWi NWi SEi sec. 16, T. 11 N. , R. 2 E. 
 
 Thickness I 
 
 Overburden 
 
 Overlying rocks 
 Shale (sample 1547) 
 Base covered 
 
 Ft. In. 
 
 10 
 30± 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 Extrusion properties Good 
 
 Water of plasticity, percent 18.0 
 
 Linear drying shrinkage, percent 4.0 
 
 1832°F 2012°F 2200°F 
 
 1.0 6.5 5.0 
 
 5.0 10.5 9.0 
 
 Tan Brick fed Brick red 
 
 Surface texture of fired test bar: Bloating and twisting started at 2200°F. 
 Surface scum at 1832°F and 2012°F. 
 
 Bonding properties: (GCS)) (optimum H2O). 
 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 
 flower pots. 
 
CLAY RESOURCES OF KNOX COUNTY 
 
 11 
 
 SAMPLE 1548 
 SW? SEi SW? sec. 18, T. 10 N. , R. 2 E. 
 
 Thickness : 
 
 Ft. In. 
 
 Overburden 
 
 Overlying rocks 
 
 Coal 
 Underclay (sample 1548) 
 Silty shale 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 25 
 1* 
 
 Extrusion properties Poor 
 
 Water of plasticity, percent 22.0 
 Linear drying shrinkage, percent 5.5 
 
 1832°F 
 +0.5 
 5.0 
 Salmon 
 
 2012°F 
 
 4.5 
 
 10.0 
 
 Brick red 
 
 2200°F 
 +5.0 
 0.5 
 Brick red 
 
 Surface texture of fired test bar: Has rough edges. Bloating started at 2200°F. 
 Bonding properties: 2.98 (GCS psi)j 1.80 (optimum H2O). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 SAMPLE 1549 
 Center of wi of SEi sec. 35, T. 10 N., R. 1 E. 
 
 Th i c kn 
 
 ess : 
 
 Ft. 
 
 In. 
 
 
 Overburden 
 
 
 
 
 
 Overlying rocks 
 
 
 25 
 
 
 Extrusion properties Good 
 
 No. 2 Coal 
 
 
 1 
 
 
 Water of plasticity, percent 20.5 
 
 Underclay (sample 1549) 
 
 
 3 
 
 
 Linear drying shrinkage, percent 5.0 
 
 Silty shale 
 
 
 
 
 
 Firing temperature 
 
 
 
 
 1832°F 2012°F 2200°F 
 
 Linear firing shrinkage, 
 
 per 
 
 cent 
 
 
 2.0 7.5 6.0 
 
 Total linear shrinkage, 
 
 perc 
 
 ent 
 
 
 7.0 12.5 11.0 
 
 Fired color 
 
 
 
 Red-brown Brick red Brick red 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 4.93 (GCS psi); 1.70 (optimum hUO). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 SAMPLE 1550 
 SEi NWi NWi sec. 32, T. 10 N. , R. 
 
 1 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 30 
 
 No. 2 Coal 1 4 
 
 Underclay (sample 1550) 2+ 
 
 Base covered 
 
 Extrusion properties Good 
 
 Water of plasticity, percent 18.0 
 Linear drying shrinkage, percent 6.0 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 1832°F 
 0.5 
 6.5 
 
 Salmon 
 
 2012°F 
 
 2200 
 
 3.5 
 
 3.5 
 
 9.5 
 
 9.5 
 
 Buff 
 
 Tan 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 4.60 (GCS psi); 1.70 (optimum H2O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
12 
 
 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 302 
 
 SAMPLE 1551 
 NEi NEi NWi sec. 31, T. 10 N. , R. 
 
 1 E. 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 
 
 No. 2 Coal 
 Underclay (sample 1551) 
 Silty shale 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 Surface texture of fired test bar: Bloating and cracking started at 2200°F. 
 Bonding properties: 4.61 (GCS psi); 2.00 (optimum H2O). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 10 
 
 Extrusior 
 
 1 properties 
 
 
 Good 
 
 i£ 
 
 Water 
 
 of 
 
 plasticity, percent 
 
 18.0 
 
 3 
 
 Linear 
 
 di 
 
 ■ying shrinkage, 
 
 perc 
 
 ent 5.0 
 
 
 1832°F 
 
 
 2012°F 
 
 
 2200 °F 
 
 t 
 
 0.0 
 
 
 6.0 
 
 
 3.5 
 
 
 5.0 
 
 
 11.0 
 
 
 8.5 
 
 
 Salmon 
 
 
 Brick red 
 
 
 Brick red 
 
 SAMPLE 1552 
 SWj SEi NWi sec. 31, T. 9 N. 
 
 R. 2 E. 
 
 Thickness: Ft. 
 
 Overburden 
 
 Overlying rocks 70 
 
 No. 2 Coal 2 
 
 Underclay (sample 1552)(exposed)3 
 
 Limestone nodules 
 
 In. 
 
 Extrusion properties 
 
 Water of plasticity, percent 
 
 Linear drying shrinkage, percent 
 
 Fair 
 
 19.0 
 
 4.5 
 
 Firing temperature 1832°F 
 
 Linear firing shrinkage, percent 2.0 
 Total linear shrinkage, percent 6.5 
 
 Fired color Yellow-brown 
 
 2012°F 
 
 5.5 
 10.0 
 Brown 
 
 2200 c 
 0.0 
 4.5 
 
 Buff 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 4.20 (GCS psi)| 1.80 (optimum H2O). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 SAMPLE 1553 
 SW3- SEi NWi sec. 36, T. 9 
 
 R. 1 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 60 
 No. 2 Coal 2 
 
 Underclay (sample 1553) 2z 
 
 Limestone nodules 
 
 Extrusion properties Good 
 
 Water of plasticity, percent 18.0 
 Linear drying shrinkage, percent 4.0 
 
 Firing temperature 1832 c 
 
 Linear firing shrinkage, percent 2.5 
 
 Total linear shrinkage, percent 6.5 
 
 Fired color Buff 
 
 2012°F 
 5.5 
 9.5 
 Light brown 
 
 2200 c 
 1.5 
 5.5 
 
 Buff 
 
 Surface texture of fired test bar: Has slightly rough edges. Bloating started 
 
 at 2200°F. 
 Bonding properties: 4.37 (GCS psi); 1.85 (optimum H2O). 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 
 drain tile, pottery, flower pots. 
 
CLAY RESOURCES OF KNOX COUNTY 
 
 13 
 
 SAMPLE 1555 
 SEi NE? SWi sec. 28, T. 9 N. , R. 2 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 20 
 
 Coal li 
 
 Underclay (sample 1555)(exposed)5 
 
 Shale 
 
 Firing temperature 1832°F 
 
 Linear firing shrinkage, percent 2.5 
 
 Total linear shrinkage, percent 6.5 
 
 Fired color Salmon 
 
 Extrusion properties Poor 
 
 Water of plasticity, percent 18.5 
 Linear drying shrinkage, percent 4.0 
 
 2012°F 
 6.5 
 
 10.5 
 Salmon 
 
 2200°F 
 6.5 
 10.5 
 Brick red 
 
 Surface texture of fired test bar: Rough edges develop at 2200°F. 
 Bonding properties: 4.15 (GCS psi); 1.95 (optimum H2O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 SAMPLE 1556 
 Center of the N line of NWj- sec. 5, T. 9 N., R. 2 E. 
 
 Extrusion properties Good 
 
 Water of plasticity, percent 20.5 
 Linear drying shrinkage, percent 5.0 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 15 
 
 Coal 7 
 
 Underclay (sample 1556) (exposed )4 
 Base covered 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 4.38 (GCS psi); 1.70 (optimum hUO). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 1832°F 
 
 2012°F 
 
 2200 °F 
 
 1.0 
 
 7.0 
 
 4.5 
 
 6.0 
 
 12.0 
 
 9.5 
 
 Pink 
 
 Brick red 
 
 Brick red 
 
 SAMPLE 1557 
 SEi SEi NWi sec. 6, T. 9 N. , R. 2 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 40 
 
 No. 2 Coal 1 2 
 
 Underclay (sample 1557) 4+ 
 
 Shale 
 
 Extrusion properties Poor 
 
 Water of plasticity, percent 22.0 
 Linear drying shrinkage, percent 5.5 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 1832°F 
 
 2.0 
 
 7.5 
 Pink 
 
 Bloating started at 2200°F 
 
 2012°F 
 
 
 
 2200°F 
 
 6.5 
 
 
 
 4.5 
 
 12.0 
 
 
 
 10.0 
 
 Brick red 
 
 
 
 Brick red 
 
 2200 °F. 
 
 Surf 
 
 ace 
 
 scum 
 
 Surface texture of fired test bar: 
 
 at 2012°F. 
 Bonding properties: 4.85 (GCS psi); 1.95 (optimum H2O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 
 flower pots. 
 
14 
 
 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 302 
 
 SAMPLE 1558 
 SEi SEi NWi sec. 6, T. 9 N. , R. 2 E. 
 
 Thickness: Ft. 
 
 Overburden 
 
 Overlying rocks 60 
 
 Coal thin 
 
 Underclay (sample 1558 )( exposed )3-§" 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 In. 
 
 Extrusion properties Poor 
 
 Water of plasticity, percent 18.0 
 
 Linear drying shrinkage, percent 4.0 
 
 1832°F 2012°F 2200°F 
 
 1.5 5.5 <-4.0 
 
 5.5 9.5 0.0 
 
 Yellow-brown Brick red Orange-buff 
 
 Surface texture of fired test bar: Has rough edges. Bloating started at 2200°F. 
 Bonding properties: 5.40 (GCS psi); 1.60 (optimum hUO). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 SAMPLE 1559 
 Center of the N line of SEj NWj- sec. 25, T. 11 N. , R. 3 E. 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 
 Shale (sample 1559) 
 Base covered 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 Surface texture of fired test bar: Has rough edges. Bloating started at 2200°F. 
 
 Bonding properties: (GCS psi); (optimum H 2 0). 
 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 10 
 
 Extrusior 
 
 i properties 
 
 
 Fair 
 
 7+ 
 
 Water 
 
 of 
 
 pla 
 
 sticity, pen 
 
 :ent 
 
 18.5 
 
 
 Linear 
 
 dryir 
 
 ig shrinkage, 
 
 perc 
 
 ent 3.0 
 
 
 1832°F 
 
 
 
 2012°F 
 
 
 2200°F 
 
 t 
 
 1.0 
 
 
 
 6.5 
 
 
 6.5 
 
 
 4.0 
 
 
 
 9.5 
 
 
 9.5 
 
 
 Red -brown 
 
 
 
 Brick red 
 
 
 Brick red 
 
 SAMPLE 1560 
 NEi NEi NEi sec. 21, T. 10 N. , R. 3 E. 
 
 Thickn 
 
 ess : 
 
 Ft. 
 
 In. 
 
 
 Overburden 
 
 
 
 
 
 Overlying rocks 
 
 
 40 
 
 
 Extrusion properties Poor 
 
 No. 2 Coal 
 
 
 2 
 
 3 
 
 Water of plasticity, percent 18.5 
 
 Underclay (sample 1560) 
 
 
 3 
 
 
 Linear drying shrinkage, percent 4.0 
 
 Calcareous sandstone 
 
 
 
 
 
 Firing temperature 
 
 
 
 
 1832°F 2012°F 2200°F 
 
 Linear firing shrinkage, 
 
 per 
 
 cent 
 
 
 1.5 5.5 +1.5 
 
 Total linear shrinkage, 
 
 perc 
 
 ent 
 
 
 5.5 9.5 2.5 
 
 Fired color 
 
 
 
 Red-brown Brick red Brick red 
 
 Surface texture of fired test bar: Has rough edges. Bloating started at 2200°F. 
 Bonding properties: 3.52 (GCS psi); 1.35 (optimum H2O). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
CLAY RESOURCES OF KNOX COUNTY 
 
 15 
 
 SAMPLE 1561 
 SEt NWi- SW? sec. 13, T. 10 N. , R. 2 E. 
 
 Thickness: Ft. 
 
 Overburden 
 
 Overlying rocks 40 
 No. 2 Coal 2# 
 
 Underclay (sample 1561) 4 
 
 Sandstone 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 In. 
 
 Extrusion properties Fair 
 
 Water of plasticity, percent 22.0 
 Linear drying shrinkage, percent 4.5 
 
 1832°F 
 2.0 
 6.5 
 
 Salmon 
 
 2012°F 
 
 8.0 
 12.5 
 Salmon 
 
 2200 °F 
 
 4.0 
 
 8.5 
 
 Brick red 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 5.80 (GCS psi)j 2.05 (optimum H2O). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 SAMPLE 1562 
 NEf SEi NWi sec. 14, T. 10 N. 
 
 Thickness: Ft. In. 
 
 R. 2 E. 
 
 Overburden 
 
 Overlying rocks 
 
 Coal 
 Underclay (sample 1562] 
 Base covered 
 
 45 Extrusion properties 
 [stripped out) Water of plasticity, percent 
 
 5 Linear drying shrinkage, percent 
 
 Poor 
 
 18.0 
 
 4.0 
 
 Firing temperature 1832°F 
 
 Linear firing shrinkage, percent 2.5 
 
 Total linear shrinkage, percent 6.5 
 
 Fired color Tan 
 
 2012°F 
 
 5.5 
 
 9.5 
 Salmon 
 
 2200 °F 
 +5.0 
 +1.0 
 Green-brown 
 
 Surface texture of fired test bar: Has rough edges. Bloating started at 2200°F. 
 Bonding properties: 4.15 (GCS psi); 1.95 (optimum H2O). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 Thickness 
 Overburden 
 
 Overlying rocks 
 
 Coal 
 Underclay (sample 1563) 
 Base covered 
 
 SAMPLE 1563 
 NE4 NEr SEi sec. 26, T. 10 N. , R. 2 E. 
 
 Ft. In. 
 
 30 
 1 
 3± 
 
 Extrusion properties Fair 
 
 Water of plasticity, percent 19.0 
 Linear drying shrinkage, percent 6.0 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 1832°F 
 
 1.0 
 
 7.0 
 Salmon 
 
 2012°F 
 
 4.5 
 10.5 
 Salmon 
 
 2200 °I 
 4.5 
 10.5 
 Brown 
 
 Surface texture of fired test bar: Slight bloating started at 2200°F. 
 Bonding properties: 3.95 (GCS psi)} 2.20 (optimum H 2 0). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
16 
 
 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 302 
 
 SAMPLE 1564 
 NW? SW? NWi sec. 13, T. 10 N., R. 1 E. 
 
 Extrusion properties Fair 
 
 Water of plasticity, percent 17.0 
 Linear drying shrinkage, percent 5.5 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 70 
 
 Coal (?) ? 
 
 Underclay (sample 1564) (exposed)2 
 Base covered 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 3.42 (GCS psi)j 2.32 (optimum H2O) . 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 1832°F 
 
 2012°F 
 
 2200 °F 
 
 1.0 
 
 5.0 
 
 +5.5 
 
 6.5 
 
 10.5 
 
 0.0 
 
 Red -brown 
 
 Brick red 
 
 Brick red 
 
 SAMPLE 1565 
 NEr SEi NEi sec. 28, T. 10 N. , R. 3 E. 
 
 Thickness: Ft. In. 
 
 Overburden 
 
 Overlying rocks 25 
 
 No. 2 Coal 2 8 
 
 Underclay (sample 1565) 3 
 
 Sandstone 
 
 Extrusion properties Good 
 
 Water of plasticity, percent 18.5 
 Linear drying shrinkage, percent 5.5 
 
 Firing temperature 1832°F 
 
 Linear firing shrinkage, percent 2.5 
 Total linear shrinkage, percent 8.0 
 
 Fired color Yellow-brown 
 
 2012°! 
 5.0 
 
 10.5 
 Brown 
 
 2200 °F 
 +10.5 
 +5.0 
 Green-brown 
 
 Surface texture of fired test bar: Bloating started at 2012°F. 
 Bonding properties: 6.10 (GCS psi)j 2.30 (optimum H2O). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 SAMPLE 1566 
 NEi SE4 NEf sec. 28, T. 10 N. , R. 3 E. 
 
 4i 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 22 
 
 Sandstone 
 Underclay (sample 1566) 
 Shale 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 Extrusion properties Fair 
 
 Water of plasticity, percent 16.0 
 Linear drying shrinkage, percent 3.0 
 
 1832 c 
 2.5 
 5.5 
 Tan 
 
 2012°F 
 
 2200 °F 
 
 6.0 
 
 +1.0 
 
 9.0 
 
 2.0 
 
 Brown 
 
 Brown 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 3.38 (GCS psi); 1.70 (optimum H 2 0). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
CLAY RESOURCES OF KNOX COUNTY 
 
 17 
 
 SAMPLE 1567 
 NW? NEi NWi sec. 13, T. 9 N. , R. 2 E. 
 
 Extrusion properties Fair 
 
 Water of plasticity, percent 20.0 
 Linear drying shrinkage, percent 5.0 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 50 
 
 Coal I2" 
 
 Underclay (sample 1567) (exposed)l 
 Base covered 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 Surface texture of fired test bar: 
 
 started at 2200°F. 
 Bonding properties: 5.09 (GCS psi); 1.95 (optimum H2O). 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 
 drain tile, pottery, flower pots. 
 
 1832°F 
 
 
 
 2012°F 
 
 
 2200 °F 
 
 3.0 
 
 
 
 5.0 
 
 
 +3.0 
 
 8.0 
 
 
 
 10.0 
 
 
 2.0 
 
 Yellow-brown 
 
 
 
 Brick red 
 
 
 Brick red 
 
 Rough edges 
 
 devc 
 
 dop 
 
 at 2012°F. 
 
 Bl( 
 
 sating 
 
 SAMPLE 1568 
 SWi NEi NWi sec. 13, T. 9 N. , R. 2 E. 
 
 Thickr 
 
 iess : 
 
 Ft. 
 
 In. 
 
 
 
 Overburden 
 
 
 
 
 
 
 Overlying rocks 
 
 
 55 
 
 
 
 Extrusion properties Good 
 
 No. 2 Coal 
 
 
 3j 
 
 
 
 Water of plasticity, percent 18.0 
 
 Underclay (sample 1568) 
 
 
 
 
 Linear drying shrinkage, percent 5.0 
 
 Green clay band 
 
 
 
 
 
 
 Firing temperature 
 
 
 
 
 1832°F 2012°F 2200°F 
 
 Linear firing shrinkage, 
 
 per 
 
 cent 
 
 
 3. 
 
 5 7.0 +2.0 
 
 Total linear shrinkage, 
 
 perc 
 
 ent 
 
 
 8. 
 
 5 12.0 3.0 
 
 Fired color 
 
 
 
 Bi 
 
 ict 
 
 : red Brick red Brick red 
 
 Surface texture of fired test bar: Bloating and twisting started at 2200°F. 
 Bonding properties: 6.07 (GCS psi); 1.80 (optimum H2O). 
 
 Possible uses: Lightweight aggregate, structural clay products, sewer pipe, 
 drain tile, pottery, flower pots. 
 
 SAMPLE 1569 
 SWi NE5- NWf sec. 13, T. 9 N. , R. 2 E. 
 
 Thickness: Ft. 
 Overburden 
 
 Overlying rocks 60 
 
 Coal 
 Underclay (sample 1569) 5^ 
 Sandstone 
 
 Firing temperature 
 Linear firing shrinkage, percent 
 Total linear shrinkage, percent 
 Fired color 
 
 In. 
 
 li 
 
 Extrusion properties 
 
 Water of plasticity, percent 
 
 Linear drying shrinkage, percent 
 
 1832°F 
 2.5 
 
 8.0 
 
 Salmon 
 
 2012°F 
 
 7.0 
 12.5 
 Salmon 
 
 Fair 
 
 22.5 
 
 5.5 
 
 2200°F 
 
 5.0 
 10.5 
 Brown 
 
 Surface texture of fired test bar: Slight bloating started at 2200°F. 
 Bonding properties: 6.12 (GCS psi); 1.80 (optimum H2O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
18 
 
 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 302 
 
 SAMPLE 1578 
 SEi SEi SWi sec. 36, T. 9 N. , R. 
 
 1 E. 
 
 Thickn 
 
 ess : 
 
 Ft. 
 
 In. 
 
 
 
 Overburden 
 
 
 
 
 
 
 Overlying rocks 
 
 
 31 
 
 
 
 Extrusion properties Good 
 
 Coal 
 
 
 
 8 
 
 
 Water of plasticity, percent 25.0 
 
 Underclay (sample 1578) 
 
 
 2 
 
 
 
 Linear drying shrinkage, percent 6.0 
 
 Coal 
 
 
 
 2 
 
 
 
 Firing temperature 
 
 
 
 
 1832°F 2012°F 2200°F 
 
 Linear firing shrinkage, 
 
 perc 
 
 :ent 
 
 
 3. 
 
 .5 8.5 +2.0 
 
 Total linear shrinkage, 
 
 percent 
 
 
 9, 
 
 ,5 14.5 4.0 
 
 Fired color 
 
 
 
 Da 
 
 rk 
 
 pink Brick red Brick red 
 
 Surface texture of fired test bar: Bloating started at 2200°F. 
 Bonding properties: 7.22 (GCS psi); 2.30 (optimum H 2 0). 
 
 Possible uses: Bonding clay, lightweight aggregate, structural clay products, 
 sewer pipe, drain tile, pottery, flower pots. 
 
 SAMPLE 1579 
 SEi SEi SWi sec. 36, T. 9 N., R. 1 E. 
 
 Thickness 
 
 Ft. In. 
 
 Extrusion properties Fair 
 
 Water of plasticity, percent 21.0 
 Linear drying shrinkage, percent 3.5 
 
 Overburden 
 
 Overlying rocks 33 
 
 Coal 2 
 
 Underclay (sample 1579) 5 8 
 Coal streak 
 
 Firing temperature 1832°F 
 
 Linear firing shrinkage, percent 2.0 
 
 Total linear shrinkage, percent 5.5 
 
 Fired color Pink 
 
 Surface texture of fired test bar: Has rough edges. 
 Bonding properties: 5.88 (GCS psi); 2.37 (optimum F-UO). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 2012°F 
 
 2200°F 
 
 8.0 
 
 8.0 
 
 11.5 
 
 11.5 
 
 Salmon 
 
 Red-brown 
 
 SAMPLE 1580 
 SEi SEi Swi sec. 36, T. 9 N., R. 1 E. 
 
 Extrusion properties Fair 
 
 Water of plasticity, percent 23.0 
 Linear drying shrinkage, percent 5.0 
 
 Thickness: Ft. In. 
 Overburden 
 
 Overlying rocks 38 
 
 Coal streak 1/8 
 
 Underclay (sample 1580) 4 2 
 Sandstone 
 
 Firing temperature 1832°F 
 Linear firing shrinkage, percent 1.5 
 
 Total linear shrinkage, percent 6.5 
 
 Fired color Pink 
 
 Surface texture of fired test bar: Slight bloating started at 2200°F. 
 Bonding properties: 4.50 (GCS psi); 1.70 (optimum H^O). 
 Possible uses: Structural clay products, sewer pipe, drain tile, pottery, 
 flower pots. 
 
 2012°F 
 
 2200°F 
 
 9.0 
 
 7.5 
 
 14.0 
 
 12.5 
 
 Salmon 
 
 Brick red 
 
CLAY RESOURCES OF KNOX COUNTY 19 
 
 SUMMARY 
 
 Most of the clay deposits tested can be used for making structural clay 
 products, lightweight aggregates, flower pots, drain tile, sewer pipe, and pottery. 
 
 The underclays studied in this report are for the most part similar in their 
 behavior. The majority had low strengths as bonding clays. Those with the higher 
 strengths probably are associated with a thin, green clay lying below them that has 
 good bonding properties but is too thin in this area to be used commercially. 
 
 Thickness of the overburden in the areas sampled ranges from 10 to 70 feet, 
 but generally is from 25 to 40 feet. 
 
 The most favorable areas for prospecting for clay are in the southern part 
 of the county. The thicker underclays generally are found along the southwest 
 border of the county close to Warren and Fulton Counties. The lightest burning 
 clays were obtained from the southwestern part of the county. 
 
 REFERENCES 
 
 American Foundrymen's Society, 1952 (sixth edition), Foundry sand handbook: 
 American Foundrymen's Society, p. 17-28, 85-89, 93-95. 
 
 Green, H. A., 1870, Geology of Knox County, in Worthen et al., Geology and 
 paleontology, vol. IV, p. 313-334, Geol . Survey of Illinois . 
 
 Jonas, Edward C, 1957, Pottery clay resources of Illinois: Illinois Geol . Survey 
 Circ. 233. 
 
 Parham, W. E., 1959, Light-burning clay resources in LaSalle County, Illinois: 
 Illinois Geol. Survey Circ. 277. 
 
-4 
 
 CIRCULAR 302 
 
 ILLINOIS STATE GEOLOGICAL SURVEY 
 
 URBAN A .%• i$? t ■ :