376 CENTRAL MINERAL REGION OF TEXAS. 



iron, as per analysis by Mr. J. H. Herndon, of this Survey. Feldspar of this 

 grade can readily be duplicated in the region in marketable amounts. Or- 

 thoclase, very pure but ferruginous, can be mined ad libitum from dikes and 

 patches in the Archaean rocks. Kaolinite is abundant as an alteration pro- 

 duct, largely of the variety carnat, chiefly pink; but this does not occur in 

 deposits of appreciable size, so far as known. 



IX. MATERIALS FOR PAINTS. 



It may be that some of the deposits of the softer red earths, which are 

 little more than degraded hematites, will come into service as pigments, and 

 even the more siliceous red sands may afford materials of value for similar 

 purposes. 



The graphitic schists of the Fernandan System and the graphitic shales of 

 the Texan System do not appear to afford enough carbon for use in this 

 manner, but if any important deposits exist, like one on Cat Creek exam- 

 ined by the writer, there is a chance of obtaining some revenue from them. 

 The Cat Creek triturated graphite is a kind of bog deposit locally found in 

 old pools in the bed of the stream, where this material has been silted-in 

 with layers of clay and sand. It was shown to me by a gentleman who 

 thought he had discoved a bog manganese ore. The black earth is, how- 

 ever, very similar to the "black mud " of the Bear Creek district in Arkan- 

 sas,* but it has been produced in a different manner. Not far above the 

 Llano County deposit the graphitic schists cross the creek, and this accumu- 

 lation has undoubtedly come from that source. With such enormous quan- 

 tities of very pure material in Arkansas, the product of numerous hot springs 

 which have worked over the earth and assorted it thoroughly, there is little 

 prospect of putting our limited and inferior supply into marketable form so 

 as to realize any profit. 



X. MISCELLANEOUS ECONOMIC PRODUCTS. 



Under this head are included some of the natural sources of revenue 

 which this district affords, as well as other materials which require some no- 

 tice here, by reason of the* efforts heretofore made to utilize them econom- 

 ically. These can better be treated under one general head than to classify 

 them independently. 



1. LITHOGRAPHIC STONE. 



Many residents of Burnet and San Saba counties have based great hopes 

 upon the supposed adaptability of some of the Hoover (Silurian) strata for 



*See Report of Geological Survey of Arkansas, vol. I, p. 104. Theo. B. Comstock. 



