Mineral description : Staurolite

Staurolite from Fauske, Norway. Twin crystal between almandine in schist.

Staurolite from Fauske, Norway. Twin crystal with almandine in schist.

Staurolite from Fauske, Norway. Staurolite and almandine in a compact mass.

Mineral class	Silicates : Nesosilicates : topaz - staurolite group
Chemical formula	FeAl4(O/OH/SiO4)2
Crystal system	Orthorombic
Habitus	Often as short prismatic crystals with twins. Also as grains in some rocks.
Cleavage	Distinct, fracture uneven to subconchoidal.
Hardness	7-7.5
Density	3.65-3.83
Color	Dark brown , yellowish brown to black. Often with transformed surfaces.
Streak	Colorless to grayish.
Luster	Vitreous to resinous.
Description	Forms at regional metamorphose at high pressures and temperatures.
Occurance	In gneiss, mica schist and quartzites.
Associates	Kyanite, muscovite, garnet, quartz.
Notes	Varieties with traces of manganese is fusable.
Locations	A rather common accessoric mineral Bergslagen. As accessorial mineral in schist. Skellefteå mining field. As accessorial mineral in schist. V. Silvberg field, Ludvika. As crystals in schist. Kalvbäcksgruvan, Falu area. As crystals in schist. Hans-Urbanson field, Riddarhyttan, Västmanland. Fauske, Norway. As fine black crystals in muscovite schist with almandine.

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