MIDDLE DEVONIAN COAL IN ILLINOIS 



TABLE 1 - NAMES AND LOCATIONS OF DIAMOND DRILL CORES SAMPLED FOR STUDY 



Sample no. 



Description 



1 



Maceration 1510, petrographic sample A-1014, chemical analysis 

 C-15776 - E. M. Self, Walden No. 1; SW% mk SE£ Sec. 24, T. 21 N., 

 R. 3 E., DeWitt County; coal at 1254 feet (382.2 m) depth; Illinois 

 State Geological Survey file no. 53810. 



2 



Maceration 1548, petrographic sample A-1275 - Earl P. Pinney Com- 

 pany, Berenz-Hanover Farm Trust No. 1; 330 feet N line, 330 feet 

 W line, NW% Sec. 25, T. 23 N. , R. 3 E. , McLean County; coal at 

 945 feet (288.0 m) depth; Illinois State Geological Survey file 

 no. C-4556. 



3 



Maceration 1589 - John P. Potsch Company, Hines No. l^A; 330 feet 

 S line, 330 feet W line, mk Sec. 20, T. 23 N., R. 3 E. , McLean 

 County; coal at 828 feet (252.4 m) depth; Illinois State Geologi- 

 cal Survey file no. C-4475. 



the coaly material in the relatively pure coal occurs as fairly round or lenticular 

 vitrinite particles, approximately 10 \± or less in diameter. 



About half of the vitrinite in the thin nonlaminated layers is irregularly 

 shaped, apparently corroded, and larger than 10 \± (pi. 1, fig. 3). The other 

 half is made up of fragments that are often rounded and mostly smaller than 10 \x 

 (pi. 1, fig. 4). The vitrinite appears to have broken down along discrete irregu- 

 lar lines of weakness, which may coincide with former cell boundaries (pi. 1, fig. 5) 

 Most of the vitrinite is free from mineral inclusions. However, disseminated py- 

 rite occasionally occurs along what may have been vascular strands (pi. 1, fig. 6), 

 and large spherical pyrite grains may occupy a portion of a vitrinite particle. 



Exinite, which consists mainly of sporinite, is found mostly in the more 

 pure and laminated parts of the coal. Ornamented and unornamented spores can 

 be distinguished in polished sections. About half of them are larger than 150 (a. 

 Large, usually very dark brown-gray spores, as shown in plate 2, figure 1, would 

 probably be assigned to Tasmanites or Leiosphaeridia, as these are the only unorna- 

 mented spores of this size range that have been observed in the macerated residue 

 (pi. 5, figs. 9-11). Most of the small spores are probably those referred to as 

 algae (?) in the palynological section (pi. 5, figs. 13-14). The rest of the exinite 

 is made up of very finely fragmented material whose composition could not be de- 

 termined but which probably includes broken spores and possibly thin cuticles. 



No resinite or waxes were observed, nor was fusinite or other inertinite 

 recognized. 



Pyrite is predominantly syngenetic, occuring as finely disseminated crys- 

 tals of only a few microns in diameter that in places form aggregates of larger py- 

 rite spheres, about 2 \± in diameter (pi. 2, fig. 2). Only a few pyrite grains as 

 large as 1 mm were found. Pyrite makes up 8 to 9 volume percent of Sample no. 1. 

 Some small crystals of sphalerite were also observed in this sample. 



Single or occasionally twinned quartz crystals that occur in the coal are 

 fairly well rounded and are up to 2 \± in diameter (pi. 2, fig. 3). The quartz 

 makes up about 5 percent by volume of the coaly material and is distributed 

 throughout. It is similar to the quartz in the sandy limestone in which the coal 

 was found. 



