Copper

specimen number:
8311558

location:
Quincy Mine, Houghton Co., Michigan, USA

description:

A grouping of sharp native copper crystals, the largest over 1.0 cm in size. In super condition.

The Quincy mine, situated on the Keweenaw Peninsula in Hancock, Houghton County, Michigan, United States, was a monumental underground native copper operation famously nicknamed Old Reliable due to its incredibly long, uninterrupted history of paying stockholder dividends. Geologically, this world-class deposit is hosted within the Mesoproterozoic-age Portage Lake Volcanics of the Midcontinent Rift System, where hot, copper-bearing hydrothermal fluids migrated upward through the volcanic stratigraphy and precipitated pure native copper and native silver within the porous, fragmental amygdaloidal tops of individual basalt lava flows, most notably the prolific Quincy Lode. Historically, the Quincy Mining Company was established in 1846 through the merger of several smaller ventures, but profitable extraction only soared after miners located the rich Pewabic amygdaloid lode in 1856, triggering decades of massive expansion and technological milestones. The company pioneered deep-shaft mining methods, culminating in the sinking of Shaft Number Two, which reached a vertical depth of over 9000 feet along the incline, and the 1920 installation of the world's largest steam-driven mine hoist to bring ore to the surface. Following nearly a century of continuous production that supported the nation's industrialization and wartime needs, sagging copper prices during the Great Depression and escalating deep-mining expenses finally forced the company to permanently cease all underground extraction in September 1931, though reclamation of copper-rich stamp sand tailings continued nearby until 1967. Through 2026, while commercial operations remain completely inactive, the Quincy mine site is preserved as a prominent National Historic Landmark District and a key partner of the Keweenaw National Historical Park, serving as a premier international destination and geological benchmark for studying nineteenth-century industrial heritage and native copper mineralization.

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