mineral
Copper-bearing rock, likely native copper in a matrix
Native copper (Cu), possibly with cuprite/malachite in a basaltic or porphyritic matrix
AI-generated identification · may be incorrectAppears reddish-brown and granular with metallic coppery green-blue patches. Native copper has Mohs hardness 2.5–3, metallic luster, cubic crystal structure, no cleavage, and specific gravity about 8.9; the surrounding matrix may be much lighter and harder.
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Physical properties
Appears reddish-brown and granular with metallic coppery green-blue patches. Native copper has Mohs hardness 2.5–3, metallic luster, cubic crystal structure, no cleavage, and specific gravity about 8.9; the surrounding matrix may be much lighter and harder.
Formation & geological history
Likely formed in a hydrothermal copper deposit where hot fluids altered volcanic rock, potentially during Precambrian to Phanerozoic mineralization. The image alone cannot establish its exact age or mineral identity.
Uses & applications
Copper is used in electrical wiring, plumbing, alloys, and industry; attractive specimens are collected, while copper minerals may be cut or polished decoratively.
Geological facts
Native copper commonly tarnishes from orange-red to brown, black, green, or blue as cuprite and carbonate minerals develop. A fresh streak or exposed surface may reveal its distinctive copper color.
Field identification & locations
Test cautiously with a steel knife: native copper is relatively soft and may deform, while the matrix is harder; copper-colored metal also leaves a reddish-brown streak. Common localities include Michigan’s Keweenaw Peninsula, Arizona, Chile, and the Democratic Republic of Congo.
