Mineral description : Magnetite

Magnetite crystals from Bastnäs. The big crystal is 12 mm across.

Massive magnetite vein from Kiruna.

Mineral class	Oxides : Hematite - Ilmenite - Magnetite group.
Chemical formula	Fe3O4
Crystal system	Cubic.
Habitus	Crystals often as well developed octaedric or dodecaedric crystals. Also as grainy or compact masses.
Cleavage	None, fracture conchoidal to uneven. Sometimes with octaedric partening.
Hardness	5.5-6.5
Density	5.2
Color	Black. Often with bluish iriscense.
Streak	Black´, opaque.
Luster	Metallic or dull.
Description
Occurance	Magnetite forms in igneous rocks (Kiruna) through magmatic differention. Also occurs in metamorphic rocks, hydrothermal veins and pegmatites.
Associates
Notes	Strongly magnetic.
Locations	A very common mineral, beeing the major part of many Swedish iron mines. Often as massive ore, but crystal localities exists also. Malmberget, Gällivare. As druses of up to 2cm crystals with smoky quartz, apatite and pyrite. Falu mine. Up to 3cm crystals in talc. Långban, Värmland. Octaedric crystals in hematite. Ladugruvan, Persberg. Harstigen. Stråssa. Bastnäs, Riddarhyttan. As octaedric crystals in chlorite schist. Norberg. Altemark, Mo i Rana, Norway. As well developed octaedric crystals in chlorite schist.

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