Copper

specimen number:
2062175

location:
Central Mine, Keweenaw Co., Michigan, USA

description:

An attractive cluster of well defined informed native copper crystals, some of these as largest 4.0 cm in size. In excellent condition. A superb display quality Michigan classic. Collected in the 1960s from the dumps of this mine.

The Central Mine, located in Keweenaw County, Michigan, was one of the most successful fissure vein mines in the Lake Superior copper district. Geologically, the mine exploited the Central Vein, a vertical fissure that cut through the basaltic layers of the Portage Lake Volcanics and the Allouez Conglomerate. This vein was remarkably productive, containing massive quantities of native copper and occasionally native silver, often found within a gangue of calcite, prehnite, and epidote. Historically, the mine was discovered in 1854 when prospectors found a prehistoric pit containing a large mass of copper. The Central Mining Company was organized shortly thereafter, and the mine began a long period of prosperity, paying dividends for over thirty consecutive years. Operations continued steadily until 1898, when the primary vein was finally exhausted. Today, the Central Mine site is well-preserved as part of a historic district, with several original mining residences still standing, serving as a prominent reminder of the 19th-century copper mining boom.

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