Mineral description : Marcasite

Marcasite crystals in calcite from Kvinnestatorp.
Another piece of marcasite crystals in calcite from Kvinnestatorp.

Mineral class Sulphides : Pyrite - Marcasite group.
Chemical formula FeS2
Crystal system Orthorombic.
Habitus Common as striated tabular crystals, often curved. Usual in cockscomb formed crystals. Also as radiating rounded aggregates and balls.
Cleavage Distinct with uneven fracture.
Hardness 6-6.5
Density 4.8-4.9
Color Light brass colored. Often with a tarnished surface covered with rust.
Streak Greenish black.
Luster Metallic.
Occurance Commonly in low tempered hydrothermal veins. Also created in sedimentary rocks.
Associates In hydrothermal veins, calcite, flourite and other sulphides.
Notes The color is lighter than pyrite.
Locations Occurs mainly in the younger part of the Swedish bedrock.
  • Skåne, Öland and Gotland is good huntingground for balls of marcasite.
  • In the Siljan area in many limestone quarries (Solberga, Osmundsberg, Kullsberg...). As crystals in calcite filled cracks with flourite and as concretions in slate.

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Mineral group index.
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Last changed : 1998-03-07