Chalcocite
Mineral Cu2S
Also called Copper glance and Redruthite
About it
Dark grey, slightly sectile copper ore, sometimes as six-sided twinned crystals. Fine crystals come from Cornwall, Bristol in Connecticut, and Butte, Montana.
- Type
- Mineral
- Group
- Sulfide, chalcocite group
- Formula
- Cu2S
- Hardness (Mohs)
- 2.5–3
- Specific gravity
- 5.5–5.8
- Streak
- blackish lead grey
- Lustre
- metallic
- Crystal system
- Monoclinic
- Colours
- dark lead grey, black
- Transparency
- opaque
- Cleavage and fracture
- indistinct; conchoidal fracture, slightly sectile
Typical values: real specimens vary. For more, see mindat.org.