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Copper with Analcime

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A branching crystallized native copper specimen, this hosting a single analcime crystal measuring just over 1.0 cm in size. Neat association piece, collected on December 8, 1998. Previous label gives exact details as to where in the mine this was collected. In good condition. 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.

Product details

SizeCabinet
Dimensions11.5 x 7.0 x 3.5 cm
Added on04/22/2026
Current owner
Unknown Owner
Acquired
Aug 2026
Previous owners
DateCollectorAcquisition price
—Weinrich MineralsNot disclosed

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Analcime
Mineral guide
Learn about Analcime
trapezohedral crystals in basalt cavities and alkaline rocks; colorless to white, sometimes pink, prized for crisp geometry and broad localities.
Analcime
Regional guide
Analcime from Seneca Mine
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Locality guide
Seneca Mine
Seneca Mine, USA, a Keweenaw copper locality near Mohawk, Michigan, notable for native copper, amygdaloidal copper, and minerals prized by collectors.