File:The quicksilver resources of California (1903) (14780540391).jpg

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. 16. DL.MP OF NEW ALMADEN MINE WORKS. alta with the underlying vein filling, and where this is miss-ing with the serpentine, is very tortuous in both directions,vertically and horizontally, so that in the gangways, which,as above mentioned, follow this contact, it is an exception tofind a straight line of any length. The stopes are locallycalled labores. The material which fills the zones of frac-turing and wherein in places cinnabar forms, is generallyrather hard and siliceous, traversed by a network of seams 12—QR 180 QUICKSILVER RESOURCES OF CALIFORNIA. of quartz and dolomite, showing repeated Assuring and fillingcontaining some inclusions of serpentine, the cinnabar formingprincipally in connection with the seams. In places the veinfilling has more of an ochreous character, the matrix beingmore or less leached out, leaving only the network of seamsintact. The San Francisco vein is mainly composed of this ochreous
Text Appearing After Image:
PHOTO Xo. 17. DUMP OF GREY SHAFT AND MINE HILL,XEW ALMADEN. ore, wherein are found bodies of ven,- hard rock, resemblingdiorite, verj irregularly fractured. In this vein, the ochreousmaterial lies on the serpentine, no gradual change taking placefrom the former into the latter, which for from 8 to lo feet fromthe vein is changed into a clayey material, gradually changinginto hard serpentine. The general character of the vein filling indicates that, as inmost of the other quicksilver deposits in the State, the deposi- SANTA CLARA COUNTY. 181 tion of cinnabar has been associated with the process of silici-fication, which characterizes the alteration of the rocks of theFranciscan series. The general direction of the seams in the vein filling is notparallel to the line of contact with the alta. The altais often indurated near the vein, and is then locally calledcab. This is especialh the case in the upper workings. In

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