Siegenite
Mineral CoNi2S4
About it
Steel grey nickel-cobalt sulfide, often as bright octahedrons on dolomite or with chalcopyrite. Named for the Siegerland, Germany; also from the lead mines of southeast Missouri.
- Type
- Mineral
- Group
- Sulfide, linnaeite group
- Formula
- CoNi2S4
- Hardness (Mohs)
- 4.5–5.5
- Specific gravity
- 4.5–4.8
- Streak
- greyish black
- Lustre
- metallic
- Crystal system
- Isometric (cubic)
- Colours
- light grey, steel grey, copper-red to violet tarnish
- Transparency
- opaque
- Cleavage and fracture
- imperfect cubic; uneven fracture
Typical values: real specimens vary. For more, see mindat.org.