Bornite
Mineral Cu5FeS4
Also called Peacock ore, Purple copper ore, and Variegated copper ore
About it
Bronze to copper-red when freshly broken but soon tarnishes purple and blue. An important copper ore; crystals are rare, the best from Cornwall and Dzhezkazgan, Kazakhstan.
- Type
- Mineral
- Group
- Sulfide
- Formula
- Cu5FeS4
- Hardness (Mohs)
- 3
- Specific gravity
- 5.06–5.09
- Streak
- greyish black
- Lustre
- metallic
- Crystal system
- Orthorhombic
- Colours
- copper red, bronze brown, iridescent purple-blue tarnish
- Transparency
- opaque
- Cleavage and fracture
- poor; uneven to conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.