Cornwallite with Conichalcite

specimen number:
2102421

location:
Gold Hill Mine, Tooele Co., Utah, USA

description:
Green botryoidal cornwallite rich across the top of matrix with green botryoidal pony calcite. In good condition.

The Gold Hill mine, situated within the Clifton mining district in the Deep Creek Mountains of western Tooele County, Utah, was a historic underground mining operation that produced significant amounts of arsenic, copper, silver, gold, tungsten, and lead. Geologically, the complex deposit is centered on a major Late Cretaceous-aged granodiorite stock that intruded into thick Paleozoic limestone and dolomite beds, generating a massive skarn contact-metamorphic zone. High-temperature hydrothermal fluids heavily altered the carbonate rocks, precipitating complex base-metal sulfides and sulfosalts that later underwent extensive oxidation, creating a highly diverse mineral environment renowned for rare secondary arsenates like adamite, conichalcite, and austinite. Organized mineral extraction began shortly after the initial discovery of silver-lead ore in 1869, but the most intense production surges occurred during World War I and World War II, specifically when the Western Utah Copper Company and the U.S. Smelting, Refining and Mining Company extracted massive tonnages of calcium arsenate for agricultural insecticide use. Commercial mining operations fluctuated heavily with global metal prices through the mid-twentieth century until deep-level industrial production permanently ceased in the early 1950s, leaving the site as a historic locality for geological research and mineral specimen collecting.

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