Identifier: quicksilverresou00forsrich (find matches)
Title: The quicksilver resources of California
Year: 1903 (1900s)
Authors: Forstner, William California State Mining Bureau
Subjects: Mercury mines and mining Mines and mineral resources Mercury ores
Publisher: Sacramento, Calif. : W.W. Shannon, supt. of State printing
Contributing Library: University of California Libraries
Digitizing Sponsor: Kahle/Austin Foundation and Omidyar Network

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PHOTO No. is. VICTOKl.\ SHAFT, NEW ALM.\DEN. the lower levels, it has more the character of a moist clay; theinclusions of gray sandstone, so frequent in the mines of SanLuis Obispo and San Benito counties, while not absent, aremuch less prominent. Possibly associated with this change inthe character of the alta is a difference in the distributionof the cinnabar in the pay shoots. In the upper workings thepart nearest to the alta is seldom the richest, the cinnabarforming more plentiful at from 5 to 8 feet below the alta, 182 QUICKSILVER RESOURCES OF CALIFORNIA. while in the lower workings the richest ore is invariably closeto the alta. The contact between the alta and the vein filling is verysharplj marked, but there is a gradual change of the abovedescribed vein filling into the material of the serpentine footwall, the vein material gradually carrying more serpentine,until its has entirely changed into the latter. The hanging
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PHOTO No. 19. SANTA ISABEL SHAFT, NEW ALMADEN wall is a shale, judging from surface exposures. Underground,no crosscut through the alta to the hanging wall was seen.(See Figs. 55 and 56.) In some parts of the mine, especially in the lower workings(as/, i), in the drift from the Santa Isabel shaft, southwest tothe American shaft (see plan, Fig. 57), heavy flows of gas wereencountered, principall)^ if not exclusively, consisting of car-bon dioxide, which in that drift were so strong as to force the SANTA CLARA COUNTY. 183 company to abandon the work. It is generally supposed thatthis gas is generated by the decomposition of the calcite anddolomite, which are abundant in those parts of the mine, bothin the vein filling and in the alta. In order to give an intelligible description of the formationof the ore bodies in the New Almaden mine, the old works, atpresent inaccessible, must be taken into account. The magnifi-

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