Mineral Information and Data:

CoAsS [CNMNC approved formula]

Named from the German, Kobold, "underground spirit" or "goblin," in allusion to the refusal of cobaltiferous ores to smelt properly, hence "bewitched.".

IMA status : Valid species (Pre-IMA 1832) Grandfathered
(8th edition) :  
  (02) Sulfides - Including Selenides and Tellurides
  (02.12) where Am Bn Xp, with (m+n):p=1:2
  (02.12.03) Cobaltite Group (Cubic or pseudocubic crystals)
(10th edition) :
  (02) Sulfides
  (02.E) Metal Sulfides, M:S = 1:2
  (02.EB) M:S = 1:2, with Fe, Co, Ni, PGE, etc.
Crystal system: Orthorhombic System
Point group (H-M): mm2 — pyramidal
Unit cell: a = 5.582 Ǻ, b = 5.582 Ǻ, c = 5.582 Ǻ
Crystal Habit: Crystals have isometric forms; massive, granular to compact
Twinning: Rare on {011} or {111}
Color: Tin-white, steel-gray with violet tint, grayish black
Diaphaneity: Opaque
Luster: Metallic, brilliant to dull
Hardness (Mohs): 5.5
Measured Density: 6.33 g/cm3
Cleavage: 1; {001} perfect
Tenacity: Brittle
Fracture: Uneven
Streak: Greyish black
Geologic Setting: In high-temperature hydrothermal deposits, as disseminations, and as veins in contact metamorphosed rocks.
Mineral Association: Magnetite, sphalerite, chalcopyrite, skutterudite, allanite, zoisite, scapolite,
titanite, calcite (Tunaberg, Sweden); numerous other Co–Ni sulfides and arsenides
Ore deposits: The primary mineral for cobalt. Some cobalt is also produced from weathered tropical orebodies.
Synonyms/varieties: Bright white cobalt
Other Properties: Gemstone Extremely Rare.


Origin: Espanola, Ontario, Canada
Sample size: 6 x 3 x 3 cm, crystal 8 mm
Photo: Tom Loomis


(zoom-in of above)


Euhedral cyrystals as pyritohedrons to 1-2 mm throughout matrix. As part of the larger Cobalt district complex, this operation between the years 1905 - 1956, once produced over 80,000 ounces of Silver; approximately 4,350,000 lbs. of Cobalt; 419,000 lbs. of Nickel; and 217,000 lbs. of Copper.
Origin: Agaunico mine, Cobalt, Ontario, Canada
Sample size: 6 x 6 x 4 cm
Photo: Tom Loomis


(zoom-in of above)