Skutterudite
Species
Uncommon · CoAs₃
Cobalt arsenide, tin white to steel grey, named for the Skutterud mines at Modum in Norway. Known since the Middle Ages as a source of smalt, the ground cobalt blue glass; at Modum the Blaafarveværket, the Blue Colour Works founded by the king in 1776, mined cobalt ore and made smalt until 1898. Nickel-rich members, once called chloanthite, are mined too, with arsenic as a by-product; the ore smells of garlic when crushed.
Identity
- Formula
- CoAs₃
- Chemical class
- Sulfide
- Also known as
- Smaltite, Chloanthite (nickel-rich)
- Ore of
- Nickel, Cobalt
Crystallography
- Crystal system
- Cubic
- Habits
- Cubic, Octahedral, Dodecahedral, Massive, Granular
- Fracture
- Conchoidal
Physical properties
- Mohs hardness
- 5.5
- Density
- 6.5 g/cm³
- Luster
- Metallic
- Colors
- tin white, silver gray
- Streak
- black
- Transparency
- Opaque
Geology
- Origins
- Hydrothermal
- Host rocks
- Granite
- Associated minerals
- Nickeline, Cobaltite, Arsenopyrite, Silver, Bismuth, Erythrite, Calcite, Siderite, Barite, Quartz
- Found in
- Hydrothermal vein (lode)
- Geography
- Norway (Skutterud, Modum), Germany (Schneeberg, Annaberg, Freiberg), Canada (Cobalt, Gowganda, Ontario), Morocco (Bou Azzer), France (Chalanches), England (Cornwall)
Classification
- Rarity
- Uncommon
- 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, Skutterudite. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Skutterudite. Wikipedia.
- Blaafarveværket. Wikipedia.
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