Malachite

specimen number:
2292194

location:
Empire Mine, Shoshone Co., Idaho, USA

description:
Silky green acicular crystallized malachite on matrix. In good condition. Neat locality example for the species.

The Empire mine, located in the Lelande mining district of Shoshone County, Idaho, is a historic underground operation known for producing significant base and precious metal ores, particularly lead, silver, and zinc. Geologically, the deposit consists of hydrothermal replacement veins and replacement bodies hosted within the Mesoproterozoic sedimentary rocks of the Belt Supergroup, specifically the Wallace Formation and St. Regis Formation. Mineralization is structurally controlled by regional faults and fractures associated with the Osburn Fault system, where hydrothermal fluids deposited galena, sphalerite, and tetrahedrite alongside quartz and carbonate gangue minerals. Underground mining began in the late 1880s following the initial silver-lead discoveries in the Coeur d'Alene region, with regular production and development expanding through the early 1900s. The mine experienced its peak operational period from the 1910s through the 1940s, providing critical metals during both World Wars before declining ore grades and changing market conditions led to a reduction in active extraction by the mid-twentieth century.

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