Copper

specimen number:
2062336

location:
Caledonia Mine, Ontonagon Co., Michigan, USa

description:

Choice grouping of native copper crystals with little attached matrix. This exhibits a very attractive patina. In good condition.

The Caledonia mine, located near Mass City in Ontonagon County, Michigan, was a notable underground copper mine situated along the historic Keweenaw Peninsula copper range. Geologically, the deposit is hosted within the Neoproterozoic Portage Lake Volcanics, where native copper and associated secondary minerals like datolite, epidote, and calcite precipitated from deep-seated, low-temperature hydrothermal fluids within the vesicular tops and brecciated flow fronts of basaltic lava sequences, specifically the Portage Lake lava flows. Initial mining operations began in 1863 under the Caledonia Mining Company, but the property experienced sporadic activity, shifting ownership and undergoing several periods of dormancy through the late nineteenth and twentieth centuries. In 1985, the mine was acquired by Red Metal Minerals, which operated it as a commercial specimen-mining venture and a popular tourist destination for mineral collectors until underground operations ceased and the mine was secured in the early 2010s.

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