The quicksilver resources of California . from themouth the tunnel intersects a sandstone dike, about 6 feetwide, course N. 60° E. The metamorphic sandstone is in places altered to quartzite,and in other places is somewhat porphyritic. It shows zonesof fractures, nearly parallel with the contact, not over one toone and a half inches interdistant. These are sometimes cutoff by a set of more irregular cross fractures, causing the rockto break very irregularly, sometimes conchoidal. The oreforms principally in the zones of parallel fracturing and adjoin-ing thereto. Where the fissuring allowed it
The quicksilver resources of California . from themouth the tunnel intersects a sandstone dike, about 6 feetwide, course N. 60° E. The metamorphic sandstone is in places altered to quartzite,and in other places is somewhat porphyritic. It shows zonesof fractures, nearly parallel with the contact, not over one toone and a half inches interdistant. These are sometimes cutoff by a set of more irregular cross fractures, causing the rockto break very irregularly, sometimes conchoidal. The oreforms principally in the zones of parallel fracturing and adjoin-ing thereto. Where the fissuring allowed it, the cinnabar wasdeposited with a quartzose gangue. Often it forms face metalon the fissure walls, which show signs of movements after thedeposition. Where the rock is more compact, small aggregatesof minute cinnabar crystals are disseminated through the rock,generally associated with iron pyrite. The mineralization wascontemporaneous with, or anterior to, this metamorphism. 96 QUICKSILVER RESOURCES OF CALIFORNIA. 200 _J /?£?£ r. Possibl}- the cinnabar wasoriginally diffused throughthe sandstone and leached//. out and concentrated during^ the metamorphism of thesandstone. At and below thelevel of the main tunnel theore forms exclusivel} in thesandstone, but nearer the sur-face it is found in the the point of intersectionwith the main tunnel oreshoot, the main tunnel makesan offshoot to the west toavoid the old works [see ], and continues then in anortheasterly direction (° E.). It passes first throughsandstone, and then followsthe northeastern contact be-tween the sandstone and theschists. Xo ore has as yetbeen found in this drift. Judging from the old stopes the ore body at the level of the main tunnel was |si about 70 feet long and from 15 to 25 feet wide. Below this level two ore bodies were worked ^?^^-z-^ from the shaft— one west, the other east and southeast of the shaft—sep-arated by about 60 feet of barren ground. The stope on the ore body
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectminesandmineralresou
