Azurite with Malachite

specimen number:
9273019

location:
El Cobre Mine, Concepcion del Oro, Zacatecas, Mexico

description:

Classic Mexican azurite specimen with brilliant blue translucent to transparent needlelike crystals of azurite across the top of matrix with malachite. This is in great condition.

The El Cobre mine (often historically associated with the broader Aranzazu mine complex), situated in the mountains just west of Concepcion del Oro within the Concepcion del Oro Municipality of northern Zacatecas, Mexico, is a famous underground mining operation celebrated for producing mineral specimens of azurite, tennantite, chalcopyrite, garnets, and manganese-rich pinkish calcite on quartz. Geologically, the deposit is a world-class copper-gold-silver skarn and massive sulfide replacement system developed along the contact zone where Tertiary-age granodiorite and quartz monzonite stocks intruded into thick, folded Mesozoic sedimentary carbonate units, specifically the Upper Jurassic Zuloaga Limestone and Lower Cretaceous Cupido Limestone. High-temperature hydrothermal fluids driven by these intrusions metasomatized the host limestone, creating extensive zones of copper-rich garnet-pyroxene skarn and subsequent lower-temperature sulfide veins containing rich pockets of chalcopyrite, bornite, and arsenic-bearing sulfosalts. Historically, the area saw primitive extraction by indigenous groups and initial Spanish exploration dating back to the 1530s, but systematic underground development at El Cobre intensified during the nineteenth and twentieth centuries to feed local copper smelters. Large-scale mechanized operations expanded under corporate entities like the Mazapil Copper Company and later Minera Aranzazu, which developed the deep copper-skarn horizons through a web of shafts and adits.

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