60 RIO GRANDE COAL FIELDS OF TEXAS. [bull. 164. 
below the Ostrea cortex ledge. All of the coal (or lignite) along this 
stream occurs above the oyster ledge and in all probability is Eocene. 
This coal is discussed under the Eocene coals or lignites (pp. 61 and 62). 
One other occurrence of coal is reported in the Eagle Pass forma- 
tion. Mr. Robert Thomson states that a 4-foot seam of coal was 
penetrated in a well bored by him on the line between Maverick and 
Zavalla counties, about 4 miles north of the northern line of Dimmit 
County. The writer has no further information in regard to this 
occurrence. 
MINES. 
Two mines are at present being worked in the Eagle Pass coal bed, 
in the vicinity of Eagle Pass. One is that of the Maverick County 
Coal Company, situated on the east side of Elm Creek, 4 miles north 
of Eagle Pass. A section of this mine is given on page 25. It was 
opened in 1895. The other mine was opened by L. F. Dolch & Co. in 
1898, and is about a mile south of the mine of the Maverick County Coal 
Company. The shipping of coal from the Dolch mine was begun in 
January, 1899. It is now owned by the Rio Bravo Coal Company. 
A section in this mine is given on page 24. The old Hartz mine, 
about 5 miles above Eagle Pass, on the Rio Grande, was worked on 
a slope, and is now abandoned. 
CHARACTER OF COAL. 
Specimens of the Eagle Pass coal were collected, and on them the 
following notes are based: 
The coal is dark, does not air slack, is lustrous or brownish black 
in color, has a brown streak and subcubical cleavage. Usually no 
woody structure is apparent. 
Two analyses, made by Dr. Peter Fireman, of Columbian University, 
showed a rather low percentage of water, a ratio of fixed carbon to 
volatile hydrocarbon of 1. 11 and 1. 05. The percentage of ash was high. 
The following is one of the analyses: 
Analysis of Eagle Pass coal. 
Moisture 
2.50 
40. 60 
42.72 
1.05 
14.18 
Light brown. 
Coherent, hard. 
Volatile h ydrocarbon 
Fixed carbon 
Ratio R °' \ 
uatio v h. C.j 
Ash 
Color of ash 
Coke 
