66 
RIO GRANDE COAL FIELDS OF TEXAS. 
[BULL. 1 
Penrose says i 1 "The San Tomas coal is so vastly superior to any « 
the east Texas lignites that it can not fairly be classed with them 
He gives the following analyses of the east Texas lignites and of tl 
Laredo and Eagle Pass coals. They are presented here for purpost 
of comparison. 
Analyses of Texas lignites. 
Rockdale, Milam County 
Atascosa County 
Athens, Henderson County . . . 
Rusk County 
Calvert bluff, Robertson County 
Shelby County 
Leon County 
Rockdale, Milam County 
Water. 
Per cent. 
19. 925 
13. 285 
9.100 
16. 825 
16. 475 
18. 260 
14. 670 
13.800 
Volatile 
matter. 
Per cent. 
52. 425 
59. 865 
42. 200 
46. 325 
58. 400 
43. 510 
37. 320 
43. 550 
Fixed 
carbon. 
Per cent. 
22. 000 
18. 525 
7.375 
31.475 
18. 675 
29. 530 
41.070 
36. 830 
Ash. 
Per cent. 
5. 650 
8. 325 
41. 325 
5.375 
6.450 
8.700 
6.690 
5.320 
Sulphur. 
Per cent. 
1.235 
2.360 
0. 625 
1.090 
1.330 
2.460 
0.250 
1.350 
Analyses of Laredo and Eagle Pass coals. 
Water. 
Volatile 
matter. 
Fixed 
carbon. 
Ash. 
Sulphur. 
Per cent. 
2.5 
3.675 
Per cent. 
51.05 
39. 42 
Per cent. 
39.1 
41.7 
Per cent. 
7.35 
15. 205 
Per cent. 
1.5 
0.81 
Eagle Pass coal 
CONCLUSIONS REGARDING THE RIO GRANDE EOCENE COALS. 
These coal (or more properly lignite) fields are simply the westward 
continuation of the great lignitif erous Eocene belt of eastern Texas and 
the Gulf States as far east as Alabama. The coal beds of the Rio 
Grande region range in position from Midway an to Chickasawan. 
The beds on the Neuces, in northern Zavalla County, are Midway an, 
while those around Carrizo Springs and Santo Tomas are Chickasawan. 
Although the Eocene contains many lignite beds, most of them are 
not of economic value for various reasons. They arc often thin and 
impure, and, because of a large content of moisture or because of an 
unconsolidated mechanical condition, must undergo mechanical treat- 
ment by being pressed into briquettes. These questions are discussed 
by Dumble in Brown Coal and Lignite. 2 
The only place where these Eocene coals are being worked is in the 
vicinity of Santo Tomas. The coal there is sufficiently hard to need no 
treatment. In such an investigation as this it is not possible to make 
i First Ann. Rept. Geol. Survey of Texas, 1890, p. 97. 
2 Geol. Survey of Texas, 1892. 
