Mineral Information and Data:

Glaucodot
Co0.5Fe0.5AsS [CNMNC approved formula]

Named From the Greek for "blue," in reference to its use in the dark blue glass called smalt.

IMA status : Valid species (Pre-IMA 1849) Grandfathered
CLASSIFICATION 
Dana
(8th edition) :
02.12.06.01  
  (02) Sulfides - Including Selenides and Tellurides
  (02.12) where Am Bn Xp, with (m+n):p=1:2
  (02.12.06)
  
Nickel-Strunz
(10th edition) :
02.EB.10c
  (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
Space group: Pmn2
Unit cell: a = 14.158(1) Ǻ, b = 5.6462(4) Ǻ, c = 3.3196(2)Ǻ
Crystal Habit: Crystals prismatic by elongation || [001]; less commonly || [010], striated || [001], to 7 cm; massive.
Twinning: On {101}; on {012}, forming cruciform penetration twins; also as trillings
  
Color: Grayish tin-white to reddish silver-white
Diaphaneity: Opaque
Luster: Metallic
Hardness (Mohs): 5
Measured Density: 6.055 g/cm3
Cleavage: Perfect on {010}, less so on {101}
Tenacity: Brittle
Fracture: Uneven
Streak: Black
  
Polymorphism and Series: Dimorphous with alloclasite.
Geologic Setting: In deep-seated deposits of high-temperature hydrothermal origin.
Mineral Association: Cobaltite, pyrite, chalcopyrite
  

 

Glaucodot
Euhedral crystals to 2 mm in sulfide matrix.
Origin: Hakansboda, Sweden
Sample size: 3.5 x 3 x 2 cm
Photo: Tom Loomis

 

Glaucodot
(zoom-in of above)

 

Glaucodot
Glaucodot, pair of penetrating twin crystals.
Origin: Hakansboda, Lindesberg, Västmanland, Sweden
Sample size: 1.9 x 1.8 x 1.6 cm
Photo: Rob Lavinsky

 

Glaucodot
(Another view of the above)

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