1XX REPORT OF THE STATE GEOLOGIST. 



MANGANESE. 



The only workable deposits of manganese yet defined by the Survey 

 are those of the Central Mineral Eegion. These deposits are both in 

 the form of manganese ores and of combinations of iron and manga- 

 nese ores in different proportions. 



The Spiller Mine, south of Fly Gap, Mason County, is the only 

 known occurrence of the manganese ore on an extensive scale any- 

 where in the region, although surface croppings were traced, which 

 seemed to indicate companion belts to the one which has been opened 

 at the locality mentioned. 



The ore is rather siliceous psilomelane, with patches of pyrolusite and 

 more or less black wad, filling cavities and crevices in the vein, which is 

 three or four feet wide. The ore seems to lie as an interbedded vein, and 

 numerous borings were made on it with a diamond drill, presumably for the 

 purpose of prospecting in the direction of its dip.* 



Manganese ores are found under similar circumstances in the region 

 between Packsaddle and Riley Mountains, and specimens are reported 

 both from Gillespie and Blanco counties. 



Manganese also occurs as an ingredient of the various limonitic ores, 

 and in one instance such an ore was found to contain as much as eleven 

 per cent of this metal in the form of dioxide. These deposits, however, 

 are not likely to prove of much economic value. 



BISMUTH. 



Bismuth occurs in small quantities in connection with the ores of the 

 Quitman range, and in one vein examined in the region of the Chinati 

 Mountains as much as three and one-half per cent of this metal was 

 found in the ore (galena). 



ABRASIVES. 



BUHRSTONE. 



In the Fayette Sands are found stones of excellent quality for use as 

 millstones. In Jasper and other counties millstones which have given 

 perfect satisfaction in use have been cut from certain horizons of these 

 sands. 



GRINDSTONES. 



Certain sandstones in the Carboniferous and older formations furnish 



*First Annual Report, p. 345. 



