File:Annual report of the United States Geological Survey to the Secretary of the Interior (1898) (14596193587).jpg

Identifier: annualreportofu2021geol_2 (find matches)
Title: Annual report of the United States Geological Survey to the Secretary of the Interior
Year: 1880 (1880s)
Authors: Geological Survey (U.S.)
Subjects: Geological Survey (U.S.) Geology Water-supply Forest reserves Mines and mineral resources
Publisher: Washington : G.P.O.
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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eat Monte Ciisto and Darrington, on the west side of the Cascades, andon Ruby Creek and Slate Creek, near the Canadian boundary. Thereare still other regions where promising prospects have been opened,as on the Methow and near Lake Chelan. Actual mining- operationshave been carried on in the Swauk, Peshastin, and Monte Cristo dis-tricts, but the others have not yet passed the prospecting stage. The mines in the Swauk district, near Liberty, include both placetsand veins. The country rocks art sandstones and shales of Tertiaryage and the basalt of the numerous dikes. The veins occur on eachside of the vertical dikes of basalt, and are peculiar, if not unique, incharacter. They consist of quartz and calcite, usually crowded withangular fragments of shale and sandstones, which are entirely sepa-rated one from another. A portion of one of these veins is shownon PI. XX. The walls of basalt forming one border of each of theveins are usually slicUensided, showing that much movement has taken
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OF VHfc KUSSELL.) GOLD. 207 place since they were formed. The fracturing of the adjacent strati-fied rocks is due to these movements, but the separation of the frag-ments produced seems to be due in part, at least, to the crystallizingof the quartz and calcite. I venture the suggestion that these1 min-erals, in crystallizing, have exerted a force analagous to the expansionof water on freezing, which has crowded the rock fragments asunder.These brecciated veins are usually 2 or 3 feet, and in some instances5 or 6 feet, thick. The wall adjacent to the basalt in each pair is welldetined, but the opposite wall is usually indefinite. Free gold occursboth in the quartz and in the included fragments of country rock, atleast above the surface streams: below water level it is to be expectedthat sulphurets will appear, and that the rock will cease to be free-milling. Previous to 1898 the ore from the quartz veins was workedby arastres, in several instances with highly favorable results. At thed

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