Abstract

The Getchell veins are lenticular replacement bodies lying along arcuate branches of a complex range-front fault system. The fault zone cuts all rocks of the district and is tentatively dated as late Tertiary.The more intensely mineralized portions of the deposit form a shallow blanket with roots that project downward into areas of sparse mineralization. The gold shoots are restricted to areas of intense mineralization.Native gold and native silver are the only economic minerals. The great bulk of the gold occurs in minute but microscopically visible particles. Some gold may also occur in submicroscopic particles and some may be in solid solution in pyrite and carbon.The ore minerals, dissolved in alkali sulfide solutions, are believed to have been deposited when the sulfide ion concentration in the hydrothermal liquid decreased, making unstable the double sulfides of gold, iron, and arsenic.The Getchell deposit is similar in many ways to the Nevada quicksilver deposits and present-day hot-spring deposits. The Getchell ore occurrence may represent a gradation from the common epithermal gold deposit to the cinnabar deposit. It is therefore placed close to the feeblest end of the epithermal group.

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