16 University of California Publications in Geology. [Vol. 7 



or less altered to pure white, or brownish white, masses and 

 much of it is completely kaolinized to soft white clay. This 

 kaolinization has been brought about by the action of acid or 

 alkali solutions and the soft masses in the upper zone of oxida- 

 tion are often impregnated with minute crystals of hornsilver. 



Sericite. — All of the original silicates of the rock were altered 

 by the original ascending solutions and the scant amount of 

 soft pearly sericitic muscovite now in the gangue is of secondary 

 formation. 



Rhodonite. — The rich silver ore of some of the veins shows 

 pinkish bands of rhodonite included in the quartz. Much of 

 the kaolinized feldspar is stained a pale rose color resembling 

 impure rhodonite. 



Phosphates and Arsenates : Apatite, Pseudomalachite, 

 Wavellite, Turquois, Pharmacosiderite, and 

 Cacoxenite 



Apatite. — Minute crystals of apatite line the crevices in the 

 Valley View vein, from the 140-foot to the 610-foot levels. The 

 crystals are snow-white and measure about two millimeters in 

 length. They occur as innumerable crystals forming a coating, 

 and have iodyrite crystals implanted upon them. Some of the 

 crystals have been later coated with a glaze of hyalite. The 

 crystals are combinations of the hexagonal prism with upper base 

 and occasionally very narrow faces of the unit pyramid (fig. 6). 

 This apatite has been formed as a purely secondary mineral and 

 gives no test for chlorine or fluorine. It is probably the simple 

 calcium triphosphate. 



Pseudomalachite. — This rare copper phosphate occurs in 

 small globular incrustations on the quartz in association with 

 rhodonite and hiibnerite. The globular forms are of a bright 

 emerald-green color and have a finely fibrous structure resem- 

 bling malachite. 



Wavellite. — Little spheres of white wavellite are implanted 

 on specimens of the vein quartz, but they are few in number. 

 Internally they have concentric-radiating, delicately fibrous, 

 structure. 



