590 CENTRAL MINERAL REGION OF TEXAS. 



of accumulation. This deduction, if it be not modified by future discovery, 

 makes the prospect for lead mining in the Central Mineral Eegion less hope- 

 ful than could be desired, but it need not prevent the judicious exploration 

 of certain possibly pregnant fields. 



Guides to Prospectoks. — 1. In searching for galena deposits in the 

 counties of San Saba, McCulloch, Mason, Llano, Blanco, and Gillespie, and 

 in the western portion of Burnet County, there is no need of examining any 

 locality which is not more or less covered by Cambrian or Silurian strata, i. e., 

 by sandstones or limestones. 



2. The occurrence in such areas of a greensand, or a brown weathering 

 limestone, or of both, along a line of faulting, especially near where a dense 

 but somewhat coarse-grained granite outcrops, is the best situation for ex- 

 ploring. The granite usually has inclusions of black schist fragments. 



3. The prominent break, joint, or fault in the strata should trend east of 

 north from ten to twenty degrees by the compass needle.* 



4. The galena will be found in the brown limestone or greensand, or occa- 

 sionally in dykes or in zones of distribution in other layers. 



* Corrected bearing, nearly north 25° east. 



