Linnaeite

Linnaeite is a cobalt sulfide mineral with the composition Co⁺²Co⁺³₂S₄. It was discovered in 1845 in Västmanland, Sweden, and was named to honor Carl Linnaeus (1707–1778).^[2]

Linnaeite
Linnaeite samples and polished section
General
Category	Sulfide mineral Thiospinel group Spinel structural group
Formula	Co+2Co+32S4
IMA symbol	Lin[1]
Strunz classification	2.DA.05
Crystal system	Cubic
Crystal class	Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m)
Space group	Fd3m
Unit cell	a = 9.43 Å; Z = 8
Identification
Color	Steel gray to gray violet
Crystal habit	As octahedral crystals; massive, granular
Twinning	On {111}
Cleavage	Imperfect on {001}
Fracture	Subconchoidal
Mohs scale hardness	4.5–5.5
Luster	Metallic
Streak	Grayish-black
Diaphaneity	Opaque
Specific gravity	4.8–5.8
Alters to	Tarnishes in air
References	[2][3][4]

Linnaeite forms a series with polydymite, Ni⁺²Ni⁺³₂S₄.^[5] Linnaeite is found in hydrothermal veins with other cobalt and nickel sulfides in many localities around the world.^[4]