Cobaltite is a sulfide mineral composed of cobalt, arsenic, and sulfur, CoAsS. Its impurities may contain up to 10% iron and variable amounts of nickel.[5] Structurally, it resembles pyrite (FeS2) with one of the sulfur atoms replaced by an arsenic atom.

Cobaltite from Sweden
CategorySulfide mineral
(repeating unit)
Strunz classification2.EB.25
Crystal systemOrthorhombic
Crystal classPyramidal (mm2)
(same H-M symbol)
Space groupPc21b
Unit cella = 5.582 Å,
b = 5.582 Å,
c = 5.582 Å; Z = 4
ColorReddish silver white, violet steel gray to black
Crystal habitGranular to massive, rarely as striated crystals, pseudocubic.
TwinningAbout [111] creating pseudo-cubic forms and striations
CleavagePerfect on {001}
Mohs scale hardness5.5
Density6.33 g/cm3

Although rare, it is mined as a significant source of the strategically important metal cobalt. Secondary weathering incrustations of erythrite, hydrated cobalt arsenate, are common.

The name is from the German, Kobold, "underground spirit" in allusion to the "refusal" of cobaltiferous ores to smelt as they are expected to, including the foul-smelling, poisonous fumes the ores gave off.[6] Cobaltite, which contains both arsenic and sulfur, was one of these ores.

It occurs in high-temperature hydrothermal deposits and contact metamorphic rocks. It occurs in association with magnetite, sphalerite, chalcopyrite, skutterudite, allanite, zoisite, scapolite, titanite, and calcite along with numerous other Co–Ni sulfides and arsenides.[2] It was described as early as 1832.[3]

It is found chiefly in Sweden, Norway, Germany, Cornwall, England, Canada, La Cobaltera, Chile, Australia, the Democratic Republic of the Congo, and Morocco.[2][5][4]

Cobaltite can be separated from other minerals by selective, pH controlled, flotation methods, where cobalt recovery usually involves hydrometallurgy. It can also be processed with pyrometallurgical methods, such as flash smelting.[7]


  1. ^ Mineralienatlas
  2. ^ a b c Mineral Handbook
  3. ^ a b Webmineral data
  4. ^ a b Archived 2020-07-22 at the Wayback Machine Corfo Report
  5. ^ a b Klein, Cornelus and Cornrlius Hurlbut, 1996, Manual of Mineralogy, 20th ed., Wiley, p.288, ISBN 0-471-80580-7
  6. ^ Mindat
  7. ^ "Copper-Cobalt ores". Retrieved 2018-04-04.

External linksEdit

Cubic Cobaltite, 1.6 x 1.4 x 1.1 cm, Brazil Lake Occurrence (Elizabeth Lake Mine), Sudbury District, Ontario, Canada