626 CENTRAL MINERAL REGION OF TEXAS. 



In using the map for practical purposes it must be borne in mind that local 

 complications may sometimes affect the situation in any given area, but those 

 who have not tested it will be surprised to learn how few and unimportant 

 the variations will be from the charts outlined by our work in the field. 



The prominent vein courses possess more or less of individual interest, and 

 each band may be advantageously reviewed by itself. 



THE EASTERN BURNET COUNTY BAND. 



It is hardly possible to characterize or to define the limits of the band 

 which passes northwestward across a portion of the valley of Hamilton Creek, 

 near the western bases of Holland Mountain and Lion Mountain, thence 

 across the valleys of Morgan and Beaver creeks, and on through the Silurian 

 limestones into the southeastern corner of San Saba County. It is inconstant, 

 both in continuity and composition, owing to the numerous and extensive 

 changes which have taken place in the arrangement of the containing strata 

 before and after the vein deposition. The line drawn upon my map indicates 

 in this instance a generalized course of outcrop rather than a definite projec- 

 tion of a continuous vein system. While I believe that it represents very 

 nearly the former course of a dominant soft ore vein, there is now much 

 vacant territory where the surface rocks are older than the original hard ore 

 matrix, and others in which more recent disturbances have possibly obliter- 

 ated portions of the veins which might have existed previously. Again, in 

 the same line, or not far from it, on Spring Creek headwaters especially, there 

 are some very good exposures of the hard specular ore in quartz, which in 

 part at least lie in the Burnetian trend.* Other limoniticand manganiferous 

 iron ores follow the companion course (north 25° east) to the Silurian veins 

 of the northwest trend. These transecting bands come together in the eroded 

 area west of Niggerhead Peak, between Clear Creek and Spring Creek, in 

 western Burnet County. 



Nos. 45 and 46, Table III, are examples of the composition of thelimonites 

 from two localities in this band. 



THE DISCONNECTED BURNET COUNTY OUTCROPS. 



It is possible that vein ores cross the area upon the west of the band just 

 described somewhere between the two courses laid down upon the map, in 

 southwestern Burnet County. There are outcrops of ferruginous materials 

 within that space, but diligent study has not thus far afforded satisfactory 

 proof of the existence of any definite band of workable ore. The occurrence 

 of Fernandian marbles near Niggerhead are a good indication of the presence 



* See reference to this ore field in the review of the hematites on page 621 of this Report. 



