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Copper

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Choice cluster of twinned native copper crystals with little attached matrix. Copper mining in the Keweenaw Peninsula of Michigan has a rich history spanning from pre-Columbian native copper extraction by indigenous peoples to a massive industrial boom that began in the mid-19th century, particularly following the Douglas Houghton geological report of 1841 and the subsequent mining rush of 1843. Geologically, the region is defined by the Keweenawan Rift System, a vast series of mid-Proterozoic basaltic lava flows and interbedded sedimentary conglomerate layers where native copper precipitated from hydrothermal fluids into open cavities, amygdules, and fracture zones. Mineralogically, the district is globally renowned for its massive, pure native copper masses alongside associated minerals such as crystallized native silver, datolite nodules, epidote, prehnite, and various zeolites, establishing it as one of the world's most unique and productive copper provinces before most major operations wound down by the late 20th century.

Product details

SpeciesCopper
SizeMiniature
Dimensions5.0 x 3.5 x 0.5 cm
Added on09/15/2026
Current owner
Unknown Owner
Acquired
Oct 2026
Previous owners
DateCollectorAcquisition price
—Weinrich MineralsNot disclosed

Learn more

Copper
Mineral guide
Learn about Copper
native copper with spinel-twinned crystals and arborescences; notable from Lake Superior, Itauz, Dongchuan, Corocoro, prized for color and localities.
Copper
Regional guide
Copper from Keweenaw Peninsula, Michigan, USA
Keweenaw Peninsula copper - classic native copper from Michigan, famed for wiry arborescent sprays, sharp crystal faces, and historic mines prized by collector…
Locality guide
Keweenaw Peninsula
A collector's guide to Keweenaw Peninsula, USA: its geology, mining history and notable minerals, illustrated with the 209 specimens documented from this locality on EarthWonders.