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CategorySulfosalt mineral
Chemical formulaCoAsS
ColorReddish silver white, violet steel gray to black
Crystal habitGranular to massive, rarely as striated crystals
Crystal systemOrthorhombic, pseudocubic.
TwinningAbout [111] creating pseudo-cubic forms and striations
CleavageGood in three directions
Mohs Scale hardness5.5
Optical PropertiesOpaque
Specific gravity6.33
Other Characteristicsmagnetic after heating

Cobaltite is a sulfosalt mineral composed of cobalt, arsenic and sulfur, CoAsS. It contains up to 10 percent iron and variable amounts of nickel.[3] Structuraly it resembles pyrite (FeS2) with one of the sulfur atoms replaced by an arsenic atom.

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 properly.[4]

It occurs in high temperature hydrothermal deposits and contact metamorphic rocks. It occurs in association with magnetite, sphalerite, chalcopyrite, skutterudite, allanite, zoisite, scapolite, titanite, calcite along with numerous other Co–Ni sulfides and arsenides.[1] It was described as early as 1832 and its type locality is Cobalt, Ontario.[2]

It is found chiefly in Sweden, Norway, Germany, Cornwall, England, Canada, Australia, Democratic Republic of the Congo and Morocco.[1][3]


  1. ^ a b c Mineral Handbook
  2. ^ a b Webmineral data
  3. ^ a b Klein, Cornelus and Cornrlius Hurlbut, 1996, Manual of Mineralogy, 20th ed., Wiley, p.288, ISBN 0-471-80580-7
  4. ^ Mindat
  • Mineral galleries
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Cobaltite". A list of authors is available in Wikipedia.
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