596 CENTRAL MINERAL REGION OF TEXAS. 



most by accident, in looking over earlier collections from the district, a bril- 

 liant, brittle, black mineral in quartz attracted my attention, and its high spe- 

 cific gravity was at once noticeable. A very little further examination proved 

 it to be cassiterite, yielding copious metallic scales upon reduction on char- 

 coal, with soda and potassium cyanide. The locality was given upon the label 

 as Herman Creek simply.* This stream is comparatively short, heading up 

 near Fly Gap, in Mason County, and flowing nearly south to the Llano River, 

 which it joins about seven miles above Castell. 



In the hope of determining the exact locus of the outcrop, I visited the re- 

 gion, with Mr. P. S. Ellsworth as assistant, and collected freely over a consid- 

 erable area which had previously been neglected in part, owing to lack of 

 time. The results of the trip, although very interesting, and conclusive as to 

 the occurrence of tin, are not yet wholly satisfactory in a commercial way. 

 But the evidence obtained, taken together with our studies of the stratig- 

 raphy of the region, is sufficient to warrant the belief that the known occur- 

 rences of tin ores are but the indicators of more extended and uniform 

 deposits which may be brought to light by means of the guides which our 

 present information can furnish. No workable deposits have yet been found, 

 and the reports to that effect in the newspapers did not emanate from this 

 Survey 



The history of the reported discovery of tin in Central Texas is made up 

 of a long series of blunders in determination of minerals which were regarded 

 as cassiterite by ill-informed prospectors who had seen the real article, but 

 who were prone to mistake for it such species as almandite, tourmaline, and 

 special forms of the purer iron ores. The greater portion of the tourmaline 

 of this district is indistinguishable from the cassiterite, as we now obtain it, 

 except'by such tests as the mineralogist applies. And moreover, it is unfor- 

 tunate that the very trend, viz., the oldest Archean or the Burnetian axis, in 

 which the cassiterite occurs, is the one which abounds in black tourmaline. 



There are several tracts in which the chances for the discovery of tin ore 

 are at least hopeful. In a general way it may be stated that the tin oxide 

 (cassiterite) occurs chiefly in more or less specialized cloudy or banded quartz 

 in a belt extending over a small area in western Burnet County, across Llano 

 County, and well into Mason County, a distance east and west of some fifty 

 miles. The breadth of the belt from north to south is irregular, but may be 

 said to average ten miles or more, although this method of description is very 

 unsatisfactory for a tract so much affected as this has been by subsequent 

 orographic disturbances. Starting with Barringer Hill, upon the west bank 

 of the Colorado River, from the vicinity of which another sample of tin ore 

 has been obtained, and tracing the Burnetian axis by interrupted outcrops 



Collected by Chas. Huppertz, 1888. 



