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.
Hardness 5.5-6
Density 5.9-6.2
Color Silvery gray
Streak Black to gray.
Luster Metallic, gray tarnish.
Occurance Common in many different environment. In magmatic sulphide ores (Skellefteå field), in pegmatic and hydrothermal veins and in metamorph rocks (Bergslagen).
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.

To sulphides index.
Mineral group index.
Main index.

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Last changed : 1998-03-07