UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 5, No. 9, pp. 149-153 ANDREW C. LAWSON, Editor 



BENITOITE, A NEW CALIFORNIA GEM 

 MINERAL. 



BY 



GEORGE DAVIS LOUDEEBACK, 



WITH CHEMICAL ANALYSIS BY 



WALTER C. BLASDALE. 



The mineral which is the subject of this note was discovered 

 early in this year by Mr. Hawkins and T. Edwin Sanders, who 

 were prospecting in the southern part of the Mt. Diablo range, 

 near the Ran Benito-Fresno County line, about latitude 36° 20'. 

 If was first brought to the writer's attention by Shreve & Com- 

 pany, who had purchased one of the cut stones from a lapidary 

 and who were later offered some of the rough material as sap- 

 phire. They soon determined that it was not sapphire but were 

 unable to place it, and so sought the aid of the University. Suf- 

 ficient material for the chemical analysis and for the crystallo- 

 graphic and other determinations was kindly supplied by Mr. 

 Hal Sanders of San Francisco, a brother of one of the original 

 discoverers. The writer is also indebted to Professor O'Neill for 

 the privileges of the chemical laboratory and for many courtesies. 



As the progress of the investigation has shown that it is a 

 new mineral species, it has been called benitoite. as it occurs 

 near the head waters of the San Benito River in San Benito 

 County. 



The most striking characteristic of the mineral is its blue 

 color, and selected crystals cut in the righl direction produce a 



