574 CENTRAL MINERAL REGION OF TEXAS. 



a. LARGE QUARTZ MASSES. 



There does not seem to be any good reason for separating the large quartz 

 exposures from those of the succeeding classes, except that the latter are more 

 apt to resemble in appearance the gold bearing veins of other regions. But 

 if the conditions for the deposition of gold were prevalent at the epochs of 

 quartz formation in the one case they were probably no less prominent in the 

 other. Judged from appearances only and from such criteria as miners un* 

 skilled in geologic study are prone to apply, there is no great difference be- 

 tween many of our Central Region outcrops and such auriferous masses as 

 occur in the Black Hills of Dakota and in parts of Colorado, where they are 

 profitably worked. But there is a wide divergence in the geologic conditions, 

 and this renders very doubtful the probability of developing any paying gold 

 mines in our area in these quartz deposits. 



Samples have been taken with care from many outcrops, and a number of 

 the assays reported in Table I are of this class of quartz. The principal 

 masses lie in the trend of the Burnetian System. They are most commonly 

 opaque, milk-white, and homogeneous. As shown by the assays none of 

 them are gold bearing. 



b. QUARTZ (AND OTHER) VEINS. 



There is a great variety of vein shafts in the Central Mineral Region, but 

 none of them have as yet yielded any traces of gold, excepting those which 

 traverse the copper bearing districts. The Pecan Creek and Babyhead silver 

 tract in Llano County offers a prospect of gold returns possibly sufficient to 

 offset the cost of mining in some instances, leaving what other metals may 

 be obtained to meet expenses of treatment and return the profits. There is 

 not enough gold in the veins to yield any profit by itself, so far as can be 

 judged from the developments heretofore made. 



The quartz of the veins is sometimes white, like that of the masses alluded 

 to in the preceding section, but more often rusty, cloudy, or even transpar- 

 ent. Assays of these varieties have been made in such numbers as to leave 

 no doubt of the sparcity of gold in the region. 



Some veins of irregular development and streaks of similar character in 

 different localities have been worked in the belief that gold could be obtained 

 from them, because "the veins have splendid walls." In most cases the 

 "walls" are simply planes of stratification or of jointage in much disturbed 

 schists, and the deposits have invariably failed to yield gold by assay. 1 have 

 collected freely and with great care from very many such pockets and string- 

 ers of quartz, pyrite, limonite, and other minerals, not only in every excava- 

 tion that could be found, but in natural exposures all over the region, but 

 none of the samples have returned any gold except as indicated in Table No. I. 



