Mineral description : Arsenopyrite

Arsenopyrite from Boliden.

Arsenopyrite crystals in pyrrhotine, from Västra Silvberg.

Mineral class	Sulphides : arsenopyrite - löllingite group.
Chemical formula	FeAsS
Crystal system	Monoclinic
Habitus	Often as elongated striated prismatic crystals. Sometimes almost ortorombic shaped. Also as compact to grainy masses.
Cleavage
Hardness	5.5-6
Density	5.9-6.2
Color	Silvery gray
Streak	Black to gray.
Luster	Metallic, gray tarnish.
Description
Occurance	Common in many different environment. In magmatic sulphide ores (Skellefteå field), in pegmatic and hydrothermal veins and in metamorph rocks (Bergslagen).
Associates
Notes	Smells like garlic when heated or struck. Soluble in nitric acid. A good electric conductor.
Locations	A common mineral Boliden, Västerbotten. As massive ore. Dannemora mine. As crystals in calcite. Sala silver mine, Västmanland. As needle crystals in limestone and other rocks. Stollgruvan, V Silvberg, Dalarna. A good crystal locality of up to 3cm big crystals in Pyrrhotite (magnetkis). Kogruvan, Värmland. Cm sized crystals with sphalerite in grainy limestone. Utö mines. As needles and short prismatic crystals in calcite.

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