Copper with Analcime

specimen number:
2062138

location:
Seneca #3 Mine, Keweenaw Co., Michigan, USA

description:

Neat branching crystallized native copper coming off matrix that is partially scattered with crude analcime crystals. In great condition. Collected December 8, 1998.

The Seneca Number 3 Mine, located in Keweenaw County, Michigan, was a significant part of the historic Copper Country on the Keweenaw Peninsula. Geologically, the mine targeted the Kearsarge Lode, a mineralized basaltic amygdaloid flow where native copper was deposited within the gas bubbles and fractures of ancient volcanic rock during the Mesoproterozoic Era. Unlike many other global deposits where copper is found as an ore, this region is world-famous for providing nearly pure native copper, often accompanied by secondary minerals like epidote, quartz, and occasionally silver. Historically, the Seneca Mining Company began exploring the property in the late 1800s, but the Number 3 shaft specifically saw its most active development and production between 1922 and 1939 under the management of the Calumet and Hecla Consolidated Copper Company. Although the mine faced periods of idleness due to fluctuating copper prices, it remains a classic locality for collectors of native copper and associated minerals. Today, the site is recognized for its contribution to the industrial heritage of the Lake Superior region and the unique volcanic geology of the Midcontinent Rift System.

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