602 CENTRAL MINERAL REGION OF TEXAS. 



The prolongation westward of the Burnetian axis, from Barringer Hill, 

 passes considerably north of the left hand end of the section in Figure 68. As 

 the discoveries of cassiterite seem thus far to belong to one narrow belt trend- 

 ing north 75° west from Barringer Hill, it is probable that the region in 

 which tin ore will eventually be mined, if ever commercially important, will 

 be limited to a belt somewhat narrower than that indicated upon the map 

 (Plate XXII); and as the outcrops are restricted and more or less confused 

 by later deposition and disturbances, it is reasonable to expect that certain 

 situations will yield better than others along the line. At present the indi- 

 cations are best in eastern Llano County and northwestern Mason County, 

 but I have traced the peculiar glistening titaniferous iron ores through dis- 

 connected outcrops across much of the intervening territory, and there is a 

 fair prospect that diligent search will bring to light new deposits. The axis 

 of the belt passes near Field Creek, Pontotoc, and Fredonia. The best ex- 

 posures of the peculiar ores are closely related to outcrops of Texian rocks, 

 at least geographically, and I think also geologically. A special examination 

 of the whole area of the tin belt in an economic way is essential to a thor- 

 oughly accurate estimation of the resources available. This has not been pos- 

 sible as yet with the means at the disposal of the Survey and the necessity of 

 covering unprecedentedly large areas in each field season. It is to be hoped 

 that a thorough investigation of this important subject may be undertaken 

 at an early day. 



4. ZINC. 



The absence of zinc continues to confront us, as was stated in the First 

 Annual Report (p. 344). The only claim made as yet concerning its occur- 

 rence anywhere within the limits of the maps accompanying this present Re- 

 port has been the sending in of a small crystalline fragment of "ruby" zinc 

 blend (sphalerite) by one who obtained it from another who said it came from 

 near Fredonia. The claim lacks verification, and everything militates against 

 the correctness of it. I have no doubt that it is a mistake. The mineral is 

 very similar to some of the Joplin, Missouri, ores, and nothing like it has 

 been observed by any of our staff in my district at any point, although we 

 have worked extensively over the region from which this is said to come. 



5. MANGANESE. 



The remarks made under this head in Report for 1889 (pp. 345 to 347) 

 need little modification, except to extend them by calling attention to the 

 wide areas over which the deposits there indicated may be sought with con- 

 fidence. The belts are well portrayed on the map of mineral districts (Plate 



