Copper sulfide and one of the most important copper ore minerals. Contains 79.9% copper, making it highly valuable. Color: Dark gray to black. Luster: Metallic. Streak: Dark gray to black. Cleavage: Poor. Hardness: 2.5-3. Transparency: Opaque. Crystal system: Monoclinic. Chemical formula: Cu₂S. Specific gravity: 5.5-5.8. Formation: Forms in the supergene enrichment zone of copper deposits by secondary replacement of primary sulfides. Common geological settings: USA Butte, Montana , Chile, Namibia, Peru; found in enriched copper deposits. Common look-alikes and related entries: Galena, Bornite, Argentite.
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Next: Chalcopyrite — Copper iron sulfide and the most important copper ore mineral. Often confused with pyrite but has a more brassy, often tarnished appearance.
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
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Last updated
2026-03-30T14:36:58.112683+00:00
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IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.
Copper sulfide and one of the most important copper ore minerals. Contains 79.9% copper, making it highly valuable.
How can you identify Chalcocite?
Compare several properties rather than relying on colour alone. This entry records colour: Dark gray to black; lustre: Metallic; streak: Dark gray to black; Mohs hardness: 2.5-3; cleavage: Poor; crystal system: Monoclinic; transparency: Opaque. Confirm an important identification with additional field tests or qualified laboratory work.
How does Chalcocite form?
Forms in the supergene enrichment zone of copper deposits by secondary replacement of primary sulfides.
Where is Chalcocite commonly found?
USA Butte, Montana , Chile, Namibia, Peru; found in enriched copper deposits.
What is Chalcocite commonly confused with?
Chalcocite may be confused with Galena, Bornite, Argentite. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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