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
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
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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