Enargite with Pyrite
specimen number:
2102447
location:
Leonard Mine, Butte, Montana, USA
description: The Leonard mine, located in the Butte district of Silver Bow County, Montana, was one of the premier underground producers of copper and byproduct zinc, silver, and gold within the "Richest Hill on Earth." Geologically, the deposit consists of complex, high-grade hydrothermal vein networks and massive sulfide replacement bodies hosted within the Late Cretaceous Boulder Batholith, specifically the Butte Quartz Monzonite. Intense structural deformation and successive pulses of deep-seated, copper-rich fluids deposited major ore minerals, including chalcocite, enargite, and bornite, along localized fault systems. Underground operations at the Leonard shaft began around 1898 under the Anaconda Copper Mining Company, utilizing deep vertical shafts and square-set timbering to mine the extensive vein systems down to depths exceeding 3,000 feet. The mine operated as a major economic anchor of the district through both World Wars until declining ore grades and a shift toward large-scale open-pit mining at the adjacent Berkeley Pit led to the permanent cessation of underground operations at the Leonard in 1958.
A neat loose floater double terminated lustrous metallic crystal of enargite. Small crystals of pyrite are scattered throughout. In great condition. Unusual and very nice for the species.
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