Calcite

specimen number:
1791251

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

description:
Colorless glassy and gemmy scalenohedral crystals of calcite on matrix. In good condition.

The Cliff Mine in Keweenaw County, Michigan, was the first successful large scale copper mine on the Keweenaw Peninsula and began operations in 1845. It worked rich native copper deposits in fissure veins cutting basalt of the Portage Lake Lava Series and quickly became one of the most productive mines in the region during the mid 19th century. Extensive underground shafts and drifts were developed to follow the copper bearing lodes, and the mine helped establish the Michigan copper industry. Production declined later in the century, and the mine eventually closed in 1870, remaining an important part of early American mining history.

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