Cuprite

specimen number:
1791239

location:
Copper Falls Mine, Keweenaw Co., Michigan, USA

description:
Red acicular crystals of cuprite, this is the variety known as chalcotrichite, on matrix. Good reference quality example for the species from this mining area. The specimen comes with a couple of antique labels.

The Copper Falls Mine in Keweenaw County, Michigan, was an early copper mining operation developed in the 1840s during the first wave of exploration on the Keweenaw Peninsula. The mine worked native copper found in fissure veins cutting basalt of the Portage Lake Lava Series. Underground shafts and drifts were driven to follow the copper bearing veins, but the operation never reached the scale or success of larger nearby mines. Activity was relatively short lived, and the mine closed by the late 1850s, remaining part of the early history of copper mining in Michigan.

Chalcotrichite is a fibrous variety of the mineral cuprite that forms in the oxidized zones of copper deposits. It is characterized by delicate hair like crystals that often appear as soft, velvety or silky aggregates. The color is typically bright red to deep crimson, reflecting the composition of cuprite. Chalcotrichite commonly develops as coatings or radiating sprays on matrix or within cavities and is often associated with other secondary copper minerals.

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