Hauerite

Hauerite
Hauerite crystals from Raddusa, Sicily
General
Category	Sulfide mineral, pyrite group
Formula (repeating unit)	MnS2
Strunz classification	2.EB.05a
Crystal system	Cubic
Crystal class	Diploidal (m3) H–M Symbol: (2/m 3)
Space group	Pa3
Unit cell	a = 6.107 Å; Z = 4
Identification
Formula mass	119.07 g/mol
Color	Reddish brown or brownish black
Crystal habit	Octahedral crystals and globular aggregates
Cleavage	{100} Perfect, {010} Perfect, Perfect on {001}
Fracture	Uneven to subconchoidal
Tenacity	Brittle
Mohs scale hardness	4
Luster	Metallic-adamantine
Streak	Reddish brown
Diaphaneity	Opaque to subtranslucent
Specific gravity	3.463
Optical properties	Isotropic
Refractive index	n = 2.69
References

Hauerite is a manganese sulfide mineral with the chemical formula MnS₂. It forms reddish brown or black octahedral crystals with the pyrite structure and it is usually found associated with the sulfides of other transition metals such as rambergite. It occurs in low temperature, sulfur rich environments associated with solfataras and salt deposits in association with native sulfur, realgar, gypsum and calcite.

It was discovered in Austro-Hungarian Monarchy near Banska Bystrica in what is now Slovakia in 1846 and named after the Austrian geologists, Joseph Ritter von Hauer (1778–1863) and Franz Ritter von Hauer (1822–1899).

Under high pressure conditions (P>11 GPa), Hauerite undergoes a large collapse in unit cell volume (22 %) driven by a spin-state transition.