630 CENTRAL MINERAL REGION OF TEXAS. 



and at points northwest, as on the Voca and San Saba road about one mile 

 and a half east of Voca, and what is probably the same vein appears on the 

 Pedernales River near old Westbrook Postoffice (Holden's). 



THE CAMP SAN SABA BAND. 



A large and valuable vein is visible at surface over much of the country 

 northwest and southeast of Camp San Saba, and it is especially prominent 

 near the mouth of Katemcy Creek. The ore there has rather a large per- 

 centage of phosphorus, which may be explained by the nearness of the Pots- 

 dam greensand to this particular outcrop. That this is not a type of the whole 

 vein is evident, for in its course near Herman Creek, in Mason County, it is 

 highly manganiferous; in other places so much so as to be properly regarded 

 as a manganese ore. 



5. TIT ANIFE ROUS ORES. 



Because of their secondary importance the titaniferous ores are placed last 

 in our description, although their geologic position entitles them to consider- 

 ation directly after the Fernandian iron deposits. Thus far my observations 

 have not given any hint of the existence of this class of iron ores in more 

 than two trends, and there is always a pointer to the original occurrence in 

 only one course, that of the normal Texian uplift. The titanium contained 

 in these veins, for such the accumulations almost invariably are, is evidently 

 derived from the Burnetian rocks; for the associated elements are in many 

 cases those rare metals which occur elsewhere only in Burnetian matrices. 

 The iron contents of the minerals of these veins may largely have come from 

 Fernandian material, but some of the lightly charged quartz veins of the 

 Silurian trend (north 25° east) may very well have been supplied by the Bur- 

 netian alone, or their deposits may be due in part to alteration of the Texian 

 ores. The bands indicated upon the Economic Map are pointers which may 

 serve to indicate the localities of outcrops. Others may be found, but 1 have 

 not met them heretofore. The principal exposures are in Mason County east 

 and west of Fly Gap Postoffice, in the Kothman Hills, and on Shaft Mountain. 

 The ore in the north 25° east trend occurs in patches or flakes in white 

 quartz, and is usually a titaniferous magnetite or hematite. That which lies 

 in the north-south (Texian) trend is more frequently contaminated with traces 

 or notable proportions of the rare metals of Burnetian ilk. Ordinarily this 

 class of ore may be readily distinguished from the hematite by the glistening 

 surfaces and the brittleness of the material, as well as by the black streak 

 and powder. As a rule, only a small portion of the whole is attractaole by 

 an ordinary hand magnet. 



