Vol. 5] 



Louderback. — Benitoite. 



333 



particular notice of minerals and veins occurring in similar 

 geologic surroundings without seeing either of the more char- 

 acteristic minerals of this particular deposit. And it is not 

 because these minerals are difficult to see, for on the contrary 

 they are striking in appearance. They do not occur as micro- 

 scopic forms, but always in distinctly visible crystals commonly 

 of fairly good size. It would appear reasonable to conclude 

 that the minerals have not been simply overlooked, but that 

 they are really very restricted in their occurrence and are due 

 to a special and unusual set of conditions — a peculiar variation, 

 as the writer believes, of a type of geologic activity of rather 

 general occurrence along the Coast Ranges. The locality and 

 general geological surroundings therefore assume considerable 

 interest. 



THE LOCALITY. 



The only locality of benitoite known at present lies in San 

 Benito County, California, near the Fresno County line, on a 

 short tributary of the San Benito River which joins the latter 

 near its source. It is on the west side of the Diablo Range and 

 not far from its summit line, and about twenty-five miles in 

 a straight line (probably thirty-five miles by road) north of 

 Coalinga, where the mining company that owns and works the 

 property has its headquarters and from which it ships its sup- 

 plies. 2 Its geographical position is represented on the index 

 map, plate 27. The mine is located on section 25, township 18 

 south, range 12 east, Mount Diablo base and meridian. 



2 It has been found very difficult to determine just who is the discoverer 

 of this interesting deposit. Different individuals have laid claim to this 

 title and a comparison of their various accounts shows that the ambition 

 to be so called has led to misrepresentations of the facts. As the writer 

 has already given names in his preliminary report and has found that 

 the original accounts given him are not entirely correct, he feels that a 

 further statement is due. Mr. J. M. Couch, a prospector of Coalinga, 

 grubstaked by Mr. Dallas, had in December found some deposits that 

 seemed to need further examination, and Mr. Dallas induced Mr. L. B. 

 Hawkins of Los Angeles to accompany Couch into the mountains for that 

 purpose. While out to examine some copper prospects they happened on 

 the benitoite deposit and each claims to be responsible for the discovery. 

 Having no idea of the nature of the material, they took some back to town 

 for further enlightenment. At first the idea, expressed by some "expert" 

 in Los Angeles, prevailed that the material was volcanic glass anil of no 

 value. Later some stones were cut in San Francisco, the lapidary believing 

 that they were sapphires, and for some time the property was known as 

 the Sapphire Mine. 



