Azurite with Malachite

specimen number:
2102370

location:
La Sal, San Juan Co., Utah, USA

description:

Beautiful blue bladed crystal groupings of azurite across the top of a green crystalline malachite matrix. This is in good condition. Very attractive color combination. From the early 1990s.

The La Sal copper district, located near the town of La Sal in San Juan County, Utah, comprises several historic underground and open-pit mining operations, most notably the Big Indian, Blue Jay, and Firefly mines. Geologically, the area is situated along the Lisbon Valley fault zone on the flanks of the Paradox Basin salt anticlines, where strata-bound sandstone-hosted copper deposits are localized within the Mesozoic Burro Canyon and Morrison Formations. Supergene oxidation of primary copper sulfides occurred when meteoric waters interacted with the carbonate-bearing sandstones, precipitating spectacular secondary minerals including malachite and highly prized, deep blue azurite as spherical concretions, nodules, and rich crystalline crusts within the porous rock matrix. Historically, active exploration and mining for copper and associated vanadium-uranium deposits began in the late 1890s, with intermittent industrial extraction expanding significantly during the peak operational years of the Big Indian Mining and Development Company and subsequent operators between 1913 and the mid-1970s. Commercial copper extraction eventually ceased by the late twentieth century due to the depletion of high-grade ore reserves and fluctuating base-metal prices, leaving the historic workings inactive.

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