Copper

specimen number:
1791302

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

description:
Neat multigenerational crystallized grouping of native copper without matrix. This is in good condition all around.

The Ojibway Mine, located in Keweenaw County, Michigan, was organized in 1907 and operated underground through thirteen levels before closing in 1913 due to financial and investor challenges rather than a lack of ore. Geologically, the mine is situated within the Keweenaw Peninsula's Precambrian Keweenawan rift sequence, consisting of ancient, tilted basalt lava flows and interbedded sedimentary conglomerates. Native copper mineralization occurs primarily as open-space fillings within amygdaloidal tops of basalt flows and fault zones, accompanied by secondary minerals such as calcite, quartz, and occasional silver.

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