Chalcocite

specimen number:
2133383

location:
Continental Mine, Fierro, Grant Co., New Mexico, USA

description:
Metallic gray crystallized calcite across the top of matrix. In good condition, neat locality example for the species.

The Continental mine, located in the Fierro-Hanover district of Grant County, New Mexico, was a significant underground and open-pit mining operation primarily focused on the extraction of copper and iron. Geologically, the deposit is a classic pyrometasomatic skarn formed where Cretaceous sedimentary rocks, including the Oswaldo Limestone, were intruded by the Tertiary-aged Hanover-Fierro granodiorite pluton. This intrusion released hydrothermal fluids that replaced the limestone with massive magnetite, chalcopyrite, and various silicate skarn minerals along structural fractures and contact zones. Commercial mining in the immediate area began in the late nineteenth century for iron ore, but large-scale, modern development of the Continental property expanded significantly in the mid-twentieth century when companies like United States Smelting Refining and Mining Company initiated deep underground and open-pit development. The mine experienced several periods of ownership changes, expansions, and temporary closures due to fluctuating metal prices throughout the late 1900s, with active commercial mining operations drawing to a close in the early 2000s when the property was placed on care and maintenance status.

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