Cobaltite
Rare cobalt arsenide sulfide, key source of strategic cobalt.
It is the naming mineral of the cobaltite group, whose members structurally resemble pyrite. Though rare, it is mined as a significant source of the strategically important metal cobalt.
- mineral_formula
- CoAsS
- mineral_group
- Cobaltite group (structurally resembles pyrite)
- common_impurities
- Up to 10% iron, variable nickel
- crystal_form
- Tetartoid (dodecahedron with chiral tetrahedral symmetry)
- associated_minerals
- Magnetite, sphalerite, chalcopyrite, skutterudite, allanite, zoisite, scapolite, titanite, calcite
Lore & Background
Its name derives from the element cobalt, which itself comes from the German term 'Kobold,' meaning an 'underground spirit' or 'goblin.' The notion of 'bewitched' minerals stems from cobaltite and other cobalt ores resisting medieval smelting methods, often producing foul-smelling, poisonous fumes. A variety containing much iron replacing cobalt, known as ferrocobaltite (German: Stahlkobalt), was found at Siegen in Westphalia.
Reader's Guide
Cobaltite, though rare, holds significance as a source of cobalt, a strategically important metal. It occurs in high-temperature hydrothermal deposits and contact metamorphic rocks, often associated with magnetite, sphalerite, chalcopyrite, and other Co–Ni sulfides and arsenides. Its processing involves selective, pH-controlled flotation methods, with cobalt recovery usually via hydrometallurgy, though pyrometallurgical methods such as flash smelting are also used. Secondary weathering incrustations of erythrite, a hydrated cobalt arsenate, are common on cobaltite. The mineral has been found in Sweden, Norway, Germany, Cornwall (England), Canada, Chile, Australia, the Democratic Republic of the Congo, and Morocco. Crystals from Khetri in Rajasthan, India, were used under the name 'sehta' by Indian jewellers to produce blue enamel on gold and silver ornaments. Its historical association with the term 'Kobold' reflects medieval miners' struggles with its toxic fumes.
Did You Know?
- Its name comes from the German term 'Kobold,' meaning 'underground spirit' or 'goblin.'
- A variety with much iron replacing cobalt, called ferrocobaltite, was found at Siegen in Westphalia.
- Crystals from Khetri, Rajasthan, were used by Indian jewellers to produce blue enamel on gold and silver ornaments.
Frequently Asked Questions
What is Cobaltite's composition and what impurities does it typically carry?
Its ideal formula is CoAsS, combining cobalt, arsenic, and sulfur in a single crystal lattice. In natural specimens, up to roughly 10 percent of the cobalt site can be substituted by iron, and variable trace amounts of nickel are also commonly present.
What crystal habit does Cobaltite display?
Cobaltite crystallizes in the tetartoid form, a dodecahedron that exhibits chiral tetrahedral symmetry. This means its faces are arranged so the crystal is mirror-asymmetric, producing distinct left- and right-handed (enantiomorphic) variants.
Why is Cobaltite economically important if it is so rare?
Despite limited global occurrences, Cobaltite is mined as a meaningful source of cobalt, a metal that is strategically critical for lithium-ion batteries, high-temperature superalloys, and other advanced technologies. Its value as a cobalt-bearing ore far outstrips what its relative scarcity might otherwise suggest.
What other minerals is Cobaltite commonly found alongside in the field?
Cobaltite typically occurs in association with magnetite, sphalerite, chalcopyrite, and skutterudite. It has also been recorded alongside allanite, zoisite, scapolite, titanite, and calcite in various ore deposits.
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