Magnesioferrite

minerals

oxide

spinel

magnetite

Formula: MgFe3+2O4
Multiple oxide, spinel group, forms a series with magnetite
Specific gravity: 4.6
Hardness: 6 to 6½
Streak: Black or dark red
Colour: Black, reddish-brown in transmitted light
Environments:

Metamorphic environments

Magnesioferrite is most commonly found in fumeroles where it probably formed by the reaction at high temperature of steam and ferric chloride with magnesian material (Dana). It is also found in sanidinite facies combustion-metamorphosed marl and burning coal heaps, and in metamorphosed dolostone (HOM). It is an accessory mineral in some kimberlite, gabbro and carbonatites (HOM).
Magnesioferrite is associated with hematite, titanium-rich magnetite, iron-rich diopside and dolomite, and at Långban, Sweden, occasionally with bromellite (Dana).

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