Pyrite with Calcite

specimen number:
9273015

location:
San Roberto Mine, Cozmin, Zacatecas, Mexico

description:

Brilliant somewhat iridescent lustrous crystals of pyrite golden in measuring to 1.0 cm in size across the top of a scalenohedral calcite crystal matrix. The pyrite crystals are in super condition. One of the calcite crystals are slightly cleaved as seen in the video. This is extremely pretty. The previous label refers to this as chalcopyrite, it sure looks like pyrite to me.

The San Roberto mine, situated just north of Zacatecas City within the historic Zacatecas Mining District of Zacatecas, Mexico, is a major underground mining operation known for its industrial production of copper, zinc, lead, and silver, as well as for producing notable mineral specimens of chalcopyrite, sphalerite, iridescent siderite, and botryoidal goethite. Geologically, San Roberto represents the largest and most intensely mineralized historical sector of the prominent Mala Noche Vein system, an intermediate sulphidation epithermal to mesothermal deposit hosted within structurally complex volcanic and metamorphic rocks, including the Triassic-age Zacatecas Formation. Hydrothermal mineralization along this extensive fault system occurred in episodic pulses associated with Tertiary rhyolitic magmatism, precipitating thick bands and replacement masses of pyrite and pyrrhotite closely intergrown with high-grade chalcopyrite and zinc-rich marmatitic sphalerite. Historically, shallow oxide ores were extracted from the vein system intermittently over centuries following early Spanish discoveries in the district, but modernized development at San Roberto accelerated in 1982 with the establishment of Minera Cozamin, which processed over one million tons of ore before a temporary closure in October 1996 due to low metal prices. Following a period of ownership changes and successful deep exploration drilling that proved the downward continuity of the copper-rich zone, Capstone Copper acquired the property and initiated continuous, large-scale commercial production in August 2006.

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