tin. 595 



3. TIN. 



Since my last report the question concerning the occurrence of tin in this 

 region has been given much study in the field and office. I quote from the 

 First Annual Report (page 345) all that was known at that time by myself: 



The same might be said of tin as of zinc, were it not for claims which have been made of 

 the discovery of the former in two or three separate localities. On this account, and be- 

 cause of the receipt of a very fine crystal of cassiterite (tin oxide) from a gentleman who did 

 not seem to know its nature, and who stated that it came from the stream "wash" near the 

 point where he gave it to me, I have taken much pains to search for tin ore. Failing to get 

 reactions for this metal in any of the minerals of my own or my assistants' collections, Mr. 

 Huppertz was specially charged with the examination of the locality referred to above and 

 of the adjoining region, in the hope that more of the same material might be found. But the 

 quest has been fruitless. The area is an extension of the Barriqger tract, and one not un- 

 likely to yield tin minerals, if they exist at all in the Central Mineral Region. 



Great care has also been exercised to detect tin in the rare minerals of the immediate Bar- 

 ringer district. To this date (May 1, 1890) no evidences of the presence of the metal in any 

 combination have been seen by me anywhere, although I have examined critically more 

 than eight thousand specimens collected from various parts of my district. There are areas 

 in Blanco and Gillespie counties which I have not worked over except in the most cursory 

 manner. Of these it is impossible to speak authoritatively at present, but such collections 

 of the Survey as have come under my inspection certainly contain no tin. 



On the map of Llano County, published in 1875 by A. R. Roessler, cassi- 

 terite is indicated as occurring near the southeastern corner. This is the 

 only record known to me of the discovery of tin ore in the Central Mineral 

 Region prior to my announcement in the foregoing words in 1889. Dr. 

 Edgar Everhardt, of the University of Texas, and Prof, von Streeruwitz, of 

 this Survey, have heretofore reported mere traces of tin in other ores. Our 

 investigations in spots marked by Mr. Roessler have not confirmed his report 

 as yet, and the geologic conditions there are not exactly similar to those in 

 which the tin ore occurs elsewhere. The nearest point to Roessler's reported 

 locality at which I have observed the cassiterite is some twenty miles north- 

 ward, in a different belt. 



Since the publication of the First Annual Report I have discovered this 

 mineral in the Survey collections from the Central Mineral Region in other 

 localities than the one therein doubtfully reported. A study of the areas 

 from which specimens have been taken shows that the conditions are not ex- 

 actly like those which have favored the production of silver and copper ores 

 in our district, and yet there are certain points of similarity which bring 

 these different deposits into somewhat closer relationship. The mineral re- 

 ferred to m the quotation above is undoubtedly tin oxide, but up to a recent 

 date it was the only piece of the mineral which had come under the writer's 

 eye, notwithstanding the fact that he had then studied above fifteen thousand 

 specimens in the Survey collections from the Central Mineral Region. Al- 



