Spherocobaltite

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Spherocobaltite
Sphaerocobaltite.jpg
Spherocobaltite from Peramea, Lérida, Catalonia, Spain
General
Category Carbonate mineral
Formula
(repeating unit)
CoCO3
Strunz classification 05.AB.05
Crystal symmetry Trigonal- hexagonal scalenohedral
H-M symbol: (3 2/m),
Space group: R 3c
Unit cell a = 4.65 Å, c = 14.95 Å; Z=6
Identification
Formula mass 118.94 g/mol
Color Pink to red, brown, grey, velvet-black (surface alteration)
Crystal habit Encrustations - forms crust-like aggregates on matrix, crystals uncommon: rhombohedral to discoidal
Crystal system Trigonal
Cleavage Perfect rhomboidal cleavage [1]
Mohs scale hardness 4
Luster Vitreous
Streak Pink
Diaphaneity Transparent to translucent
Specific gravity 4.13
Optical properties Uniaxial (–)
Refractive index nε = 1.600, nω = 1.885
Birefringence 0.285
Pleochroism Dichroic: 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]