Copper

specimen number:
2062338

location:
Keweenaw Peninsula, Michigan, USA

description:

Very choice large sharp crystal of native copper with minor attached matrix. In super condition, this is a great thumbnail specimen.

Copper mining in the Keweenaw Peninsula of Michigan represents one of the most historically significant mining booms in North America, focusing on the extraction of unique, massive deposits of native copper. Geologically, these deposits are hosted within the Mesoproterozoic Keweenawan Rift system, where copper precipitated from deep-seated hydrothermal fluids within the vesicular tops of basaltic lava flows and interstitial spaces of overlying sandstones and conglomerates. Native copper extraction began commercially in 1845, prompting a massive influx of mining operations that dominated global production for decades. As the shallow native copper veins faced depletion throughout the twentieth century, focus shifted toward the massive sedimentary copper sulfide deposits at the White Pine mine on the western edge of the district, which began large-scale operations in 1953. The permanent closure of the White Pine mine in 1995 marked the official end of over 150 years of continuous, major commercial copper mining on the Keweenaw Peninsula.

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