Cobaltite

Cobaltite
Cobaltite from Sweden
General
Category Sulfide mineral
Formula
(repeating unit)		 CoAsS
Strunz classification 2.EB.25
Crystal system Orthorhombic
Crystal class Pyramidal (mm2)
(same H-M symbol)
Space group Pc21b
Unit cell a = 5.582 Å,
b = 5.582 Å,
c = 5.582 Å; Z = 4
Identification
Color Reddish silver white, violet steel gray to black
Crystal habit Granular to massive, rarely as striated crystals, pseudocubic.
Twinning About [111] creating pseudo-cubic forms and striations
Cleavage Perfect on {001}
Fracture Uneven
Tenacity Brittle
Mohs scale hardness 5.5
Luster Metallic
Streak Grayish-black
Diaphaneity Opaque
Density 6.33 g/cm3
References [1][2][3][4]

Cobaltite is a sulfide mineral composed of cobalt, arsenic, and sulfur, CoAsS. It contains 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.

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.[6]

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]

Cobalt can be separated from cobaltite using a technique called flotation-separation. [7]

References

  1. ↑ Mineralienatlas
  2. 1 2 3 http://rruff.geo.arizona.edu/doclib/hom/cobaltite.pdf Mineral Handbook
  3. 1 2 http://webmineral.com/data/Cobaltite.shtml Webmineral data
  4. 1 2 https://www.corfo.cl/sites/Satellite?blobcol=urldata&blobkey=id&blobtable=MungoBlobs&blobwhere=1475166619420&ssbinary=true Corfo Report
  5. 1 2 Klein, Cornelus and Cornrlius Hurlbut, 1996, Manual of Mineralogy, 20th ed., Wiley, p.288, ISBN 0-471-80580-7
  6. ↑ http://www.mindat.org/min-1093.html Mindat
  7. ↑ "Copper-Cobalt ores". www.danafloat.com. Retrieved 2018-04-04.
  • Wikisource Spencer, Leonard James (1911). "Cobaltite". In Chisholm, Hugh. Encyclopædia Britannica. 6 (11th ed.). Cambridge University Press. p. 605.
Cubic Cobaltite, 1.6 x 1.4 x 1.1 cm, Brazil Lake Occurrence (Elizabeth Lake Mine), Sudbury District, Ontario, Canada
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