mineral
Polished native copper nugget
Native copper (Cu), likely with cuprite/tenorite and iron-oxide alteration
AI-generated identification · may be incorrectMetallic to submetallic luster; dark copper-brown patina with brighter copper-colored patches, irregular rounded form, and probable pits from natural weathering. Mohs hardness 2.5–3, cubic crystal system, malleable, specific gravity about 8.9; copper-red streak on unglazed porcelain.
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Physical properties
Metallic to submetallic luster; dark copper-brown patina with brighter copper-colored patches, irregular rounded form, and probable pits from natural weathering. Mohs hardness 2.5–3, cubic crystal system, malleable, specific gravity about 8.9; copper-red streak on unglazed porcelain.
Formation & geological history
Formed by hydrothermal fluids in basaltic volcanic rocks, where copper precipitated in fractures and cavities; oxidation produced the dark cuprite/tenorite coating. Native copper deposits are commonly Precambrian to Phanerozoic in age, especially in the Lake Superior region.
Uses & applications
Collected as a mineral specimen and sometimes used for educational displays; copper itself is important in electrical wiring, plumbing, alloys, and industry, but this irregular polished piece has little practical material value.
Geological facts
Copper commonly develops green carbonate patinas outdoors, while polished or oil-treated surfaces can appear nearly black. Its high density makes it noticeably heavy for its size.
Field identification & locations
Identify by unusual heft, metallic reddish-brown color, malleability, and copper-red streak; test cautiously because coatings can obscure these traits. Common localities include Michigan, Wisconsin, Arizona, Russia, and Chile.
