Chemistry:Trogtalite

Short description: Sulfide mineral

Trogtalite
Piece of oosterboschite with cuprosklodowskite, quartz, and brown oxidized trogtalite from the Musonoi mine. From the Howard Belsky collection.
General
Category	Selenide minerals
Formula (repeating unit)	CoSe2
Strunz classification	2.EB.05a
Dana classification	2.12.1.5
Crystal system	Cubic
Crystal class	Diploidal (m3) H-M symbol: (2/m 3)
Space group	Pa3
Identification
Color	Rose-violet
Crystal habit	Irregular grains
Mohs scale hardness	3.5–5.5
|re|er}}	Metallic
Diaphaneity	Opaque
Density	7.12 (calculated) 7.09 (synthetic)
Pleochroism	None
Ultraviolet fluorescence	None
Solubility	Insoluble
Common impurities	Cu, Pd
References

Trogtalite is a rare selenide mineral with the formula CoSe_2. It crystallizes in the cubic system and is part of the pyrite group, consisting of Co²⁺ and Se₂²⁻ ions. It has a rose-violet colour and its crystals are opaque. It often occurs as grains. It was thought to be dimorphous with hastite, but this was discredited in 2009. Hastite turned out to be the iron selenide mineral ferroselite. It forms a solid solution series with kruťaite.

Occurrence

Trogtalite was first found in 1955 in Trogtal quarry, Lautenthal, Harz Mountains, Germany, after which it was also named. It often occurs intergrown with clausthalite grains at this locality. It has also been found in the Musonoi Cu–Co mine, Kolwezi, Katanga Province, Congo and in Argentina, in Tuminico, Sierra de Cacho, and in Los Llantenes, La Rioja Province. It is often found together with clausthalite, ferroselite, bornhardtite, native selenium, gold, and oosterboschite.

See also

• List of minerals