Chalcocite
Species
Common · Cu₂S
Copper glance, the blackish lead grey sulfide that holds nearly 80 per cent copper by weight and gives it up easily, which has made it one of the most profitable copper ores for centuries. Most of it forms below the oxidised cap of copper deposits, where leached copper is laid down again, and it is mined from the great low-grade porphyry orebodies; the old Cornish mines gave fine crystals.
Identity
- Formula
- Cu₂S
- Chemical class
- Sulfide
- Also known as
- Copper glance, Vitreous copper, Redruthite, Chalcosine
- Ore of
- Copper
Crystallography
- Crystal system
- Monoclinic
- Habits
- Prismatic, Tabular, Massive
- Fracture
- Conchoidal
Physical properties
- Mohs hardness
- 2.5
- Density
- 5.7 g/cm³
- Luster
- Metallic
- Colors
- lead-gray, black
- Streak
- blackish lead-gray
- Transparency
- Opaque
Geology
- Origins
- Hydrothermal, Sedimentary
- Host rocks
- Granite
- Associated minerals
- Pyrite, Chalcopyrite, Covellite, Bornite, Molybdenite
- Found in
- Hydrothermal vein (lode), Oxidized zone (gossan), Porphyry copper deposit
- Geography
- USA (Butte, Montana; Bisbee, Arizona; Kennicott, Alaska), England (Cornwall), Russia (Ural Mountains), South Africa (Namaqualand), DR Congo (Kolwezi)
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Chalcocite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Chalcocite. Wikipedia.
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