Malachite with Calcite

specimen number:
2102328

location:
Bisbee, Cochise Co., Arizona, USA

description:
Velvety green crystals of malachite across a brecciated matrix with calcite. Some damage present as seen. This confined mainly to the calcite.

The Bisbee mineral district, situated within the Mule Mountains of Cochise County, Arizona, United States, is a legendary mining locality world-famous for producing spectacular copper specimens, including exceptional capillary arrays of the cuprite variety known as chalcotrichite, which features delicate, needle-like, or plush mats of interconnected bright red crystals. Geologically, this immense deposit is a complex porphyry copper system centered around the Jurassic-age Sacramento Stock, an igneous intrusion that triggered extensive contact metamorphism and skarn formation within surrounding Paleozoic limestone beds. Over millions of years, intense supergene weathering and descending groundwater oxidised the primary sulfide ore bodies near the surface, leaching copper ions and reprecipitating them within open dissolution cavities and fractures to form rich zones of secondary minerals, allowing the fragile, hair-like chalcotrichite needles to grow undisturbed inside low-pressure clay-lined pockets alongside malachite, azurite, and native copper. Historically, organized large-scale underground shaft and open-pit mining at Bisbee began in 1880 following the discovery of the rich Copper Queen vein, escalating into a massive industrial powerhouse managed by the Copper Queen Consolidated Mining Company and later the Phelps Dodge Corporation. Prolific underground workings like the Czar, Briggs, and Cole shafts, along with the massive Lavender Pit, operated continuously for nearly a century until declining ore grades and high operational costs forced the permanent cessation of all commercial mining operations in 1975.

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