360 



QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



rfel 



a belt of black opaline material frequently known to the miners of northern 

 California as quicksilver rock. This opaline layer, being firmer and less 

 easily decomposed than tlie surrounding masses, projects from the adjoining 

 rocks as a cropping. The ore bodies are in direct contact with the sand- 

 stone, but are for the most part inclosed on three sides by serpentine. In 

 a few cases small bodies of the ore extend into the opaline zone, which is, 

 as a rule, separated from the ore by a few feet 

 of unaltered serpentine. These relations are best 

 shown by the accompanying cross-section (Fig. 15). 

 The distribution of ore in the direction of the 

 strike is irregular, the ore bodies being divided 

 from one another by barren ground, and, as has 

 been the case in so many mines, they were richest 

 near the suiface. The following longitudinal sec- 

 tion of the deposit shows the distribution of tlie 

 chimneys of ore so far as they liave been traced 

 Fig. 16). 



The ore has been for the most part cinnabar, 

 but at one point a body of rock strongly impreg- 

 nated with native quicksilver was found. . Pyrite 

 is abundant. Some of the cinnabar is so endjedded 

 in quartz as to show that the deposition of the two 

 minerals was simultaneous. Bitumen occurs, particularly in cavities in the 

 opaline belt. The new, seemingly very ill defined species of bitumen, 

 posepnyte, was described from this mine by Schruckinger. This bitumen 

 is said to consist of a mixture of ozocerite and a substance soluble in 

 ether which has the formula C"H^''0''. 



Specimens collected at the Great Western were examined by Dr. Mel- 

 ville with the following results : 



The substance is reddish brown, resinous, soft, elastic, has a specific 

 gravity of 0.985, and is highly electrified by friction in an agate mortar. 

 On platinum foil it volatilizes partially at low temperatures with a rather 

 suffocating, aromatic odor ; at a higher temperature it becomes black and 

 fu.ses and boils like rubber; at a dull-red heat an incombustible, light-brown 



Fig. 15. Vertical cross - section 

 throagh sliaft No. 3, Gre.it Western 

 mine. Scale, 200 feet to 1 inch. 



