Datolite with Copper

specimen number:
2062286

location:
Centennial #2 Mine, Houghton Co., Michigan, USA

description:
A datolite nodule, this cut in half, showing inclusions of native copper. The size provided is the size of the box in which these are displayed.

The Centennial No. 2 mine, located near Calumet in Houghton County, Michigan, was a major underground native copper operation within the historic Keweenaw copper district. Geologically, the mine worked the Kearsarge Amygdaloid Lode, a volcanic stratum composed of Precambrian basaltic lava flows where vesicular cavities and fractures were filled with native copper deposited by ancient hydrothermal fluids. Initial shaft sinking at the No. 2 site began in 1896 under the reorganized Centennial Copper Company, targeting this copper-bearing amygdaloid belt. The corporate producer Calumet and Hecla Consolidated Copper Company took direct control of the operations in 1923, and although the facility was idled due to adverse economic conditions during the Great Depression, the shaft was reactivated in 1944 to supply raw materials during World War II. The Centennial No. 2 shaft remained an active and productive asset for the company throughout the post-war era until underground extraction was permanently discontinued in 1966.

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