Spherocobaltite

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Spherocobaltite
Sphaerocobaltite.jpg
Spherocobaltite from Peramea, Lérida, Catalonia, Spain
General
CategoryCarbonate mineral
Formula
(repeating unit)
CoCO3
Strunz classification5.AB.05
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space groupR3c
Unit cella = 4.65, c = 14.95 [Å]; Z = 6
Identification
Formula mass118.94 g/mol
ColorPink to red, brown, grey, velvet-black (surface alteration)
Crystal habitEncrustations - forms crust-like aggregates on matrix, crystals uncommon: rhombohedral to discoidal
CleavagePerfect rhomboidal cleavage [1]
Mohs scale hardness4
LusterVitreous
StreakPink
DiaphaneityTransparent to translucent
Specific gravity4.13
Optical propertiesUniaxial (–)
Refractive indexnε = 1.600, nω = 1.885
Birefringence0.285
PleochroismDichroic: O = violet-red; E = rose-red
References[1][2][3]

Spherocobaltite or sphaerocobaltite is a cobalt carbonate mineral with chemical composition CoCO3. In its (rare) pure form, it is typically a rose-red color, but impure specimens can be shades of pink to pale brown. It crystallizes in the trigonal crystal system.

Discovery and occurrence[edit]

Spherocobaltite was first described in 1877 for an occurrence within cobalt and nickel veins in the St. Daniel Mine of the Schneeberg District, Erzgebirge, Saxony, Germany. The name is from the Greek "sphaira", sphere, and cobalt, in reference to its typical crystal habit and composition.[1] It occurs within hydrothermal cobalt-bearing mineral deposits as a rare phase associated with roselite, erythrite, annabergite and cobalt rich calcite and dolomite.[3]

Cluster of spherocobaltite crystals from the Katanga Copper Crescent, Katanga (Shaba), Democratic Republic of Congo (size: 11.5 x 6.0 x 4.5 cm)

References[edit]

Further reading[edit]