Malachite

specimen number:
2102368

location:
Hecla Mine, Beaverhead Co., Montana, USA

description:

Neat locality example for the species, brilliant green botryoidal crystallized malachite across the front of matrix. This is in really good condition.

The Hecla mine, situated within the Bryant mining district in Beaverhead County, Montana, was a significant historic underground mining complex located high in the Pioneer Mountains near the town of Melrose. Geologically, the deposit consists of structurally controlled, polymetallic carbonate-replacement bodies localized along the contact zone between Paleozoic limestones, particularly the Cambrian Hasmark Formation, and intrusive granitic rocks of the Cretaceous-Paleogene Pioneer Batholith. Hydrothermal fluids originating from the batholith migrated through complex fault and shear zones, dissolving the carbonate host rocks and precipitating rich sulfide ores composed of argentiferous galena, sphalerite, tetrahedrite, and chalcopyrite, which underwent extensive supergene enrichment near the surface to form high-grade lead-silver-copper carbonates. Historically, the original claims were first discovered in 1872, leading to the formation of the Hecla Consolidated Mining Company in 1877, which systematically consolidated and developed major connected workings including the Atlantis, Cleve, and Lion mines. The operation became one of Montana's premier silver and lead producers during the late nineteenth century, constructing a major smelter at Glendale and running continuously until 1904, when the depletion of the primary high-grade ore bodies combined with falling silver prices forced the permanent cessation of large-scale corporate operations. Through 2026, while the remote high-altitude site features mostly ruined stone structures and flooded portals, the extensive rock dumps and surrounding district remain a critical reference locality for geological researchers studying intrusion-related skarn and replacement mineralization in the northern Rocky Mountains.

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