Calcite with Aurichalcite

specimen number:
2292411

location:
Holbrook Mine, Bisbee, Arizona, USA

description:
A stalactitic grouping of lustrous calcite crystals, these a light bluish green in color due to the presence of aurichalcite. In good condition.

The Holbrook Mine, located in Bisbee, Arizona, was established in March 1881 when the Holbrook and Cave claims were first developed. Geologically, the mine is situated within the Warren Mining District, where copper mineralization formed through hydrothermal processes associated with the intrusion of the nearby Sacramento Hill granite porphyry during the Jurassic period. These hot fluids reacted with Paleozoic limestones to deposit massive copper sulfides. Subsequent weathering and groundwater circulation created a highly oxidized zone, transforming the primary sulfides into rich pockets of secondary copper carbonates, most notably deep blue azurite and green malachite. Historically, the property was acquired by Phelps, Dodge and Company in 1888 and consolidated under the Copper Queen Consolidated Mining Company in 1897, eventually producing up to 1,000 tons of ore per day. The mine suffered a major underground cave-in in July 1906 due to shifting ground. Underground mining at the site eventually ceased in 1944, and much of the original Holbrook shaft was consumed by the expansion of the adjacent Lavender Pit open-pit mining operations in 1969.

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