Native Copper
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 4.0)
Mineral NameNative Copper
Chemical FormulaCu
Mohs Hardness2.5
Crystal Systemcubic
Lustermetallic
Streak Colorcopper-red
Cleavagenone
Fracturehackly
Specific Gravity8.9
Colorscopper-red, brown, green (tarnish)
Transparencyopaque
Type LocalityLake Superior, Keweenaw County, Michigan, USA
Mineral GroupNative Elements
Useselectrical conductor, plumbing, coinage, alloys, collector
Associated Mineralscalcite, epidote, quartz, silver, prehnite, datolite, zeolites
Rarityuncommon
Description
This specimen features an intricate, dendritic growth of native copper crystals, displaying a reddish-brown tarnished metallic luster with some brighter copper-red areas and hints of green oxidation. The individual crystals are well-formed, contributing to the overall arborescent structure.
Geological Context
Native copper commonly forms in basaltic lava flows, filling amygdules and fissures, where hydrothermal fluids deposit the pure metal. The Michigan deposits are renowned for their large masses and crystalline forms found within Precambrian flood basalts.
