Rhodochrosite with Pyrite

specimen number:
2282026

location:
Emma Mine, Butte, Montana, USA

description:
Pink rhombohedral crystals of rhodochrosite across the top of matrix with micro pyrite.

The Emma Mine, located in the south-central portion of the historic Butte District in Silver Bow County, Montana, was a major underground producer of manganese, zinc, lead, and silver. Geologically, the deposit consists of deep-seated, complex hydrothermal vein systems hosted within the late Cretaceous Boulder Batholith, specifically the Butte Quartz Monzonite. These veins underwent extensive secondary enrichment, resulting in massive ore bodies containing rhodochrosite, sphalerite, and galena. Originally staked in the late nineteenth century during Butte's early mining boom, the Emma Mine saw its most significant development and sustained commercial operation under the Anaconda Copper Mining Company starting around 1916. It became a critical strategic domestic source of manganese during both World War I and World War II, with aggressive shaft sinking and production continuing until the mid-twentieth century when declining ore grades and market shifts led to the permanent cessation of large-scale operations in the late 1950s.

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