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Magnesioferrite - Ochtendung, Eifel, Germany.jpg
Magnesioferrite from Ochtendung, Eifel, Germany
Category Oxide minerals
Spinel group
Spinel structural group
(repeating unit)
Strunz classification 4.BB.05
Crystal system Cubic
Crystal class Hexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space group Fd3m
Unit cell a = 8.3866 Å; Z = 8
Color Black to brownish black
Crystal habit As octahedral crystals, massive granular
Twinning Twin plane {111}, contact twins
Cleavage On {111}
Fracture Uneven
Tenacity Brittle
Mohs scale hardness 6 - 6.5
Luster Metallic, semimetallic, dull
Streak Dark red
Diaphaneity Opaque, transparent in thin fragments
Specific gravity 4.55 – 4.65 measured
Optical properties Isotropic
Refractive index n = 2.38
Other characteristics Magnetic
References [1][2][3]

Magnesioferrite is a magnesium iron oxide mineral, a member of the magnetite series of spinels. Magnesioferrite crystallizes as black metallic octahedral crystals. It is named after its chemical composition of magnesium and ferric iron. The density is 4.6 - 4.7 (average = 4.65), and the diaphaniety is opaque. Occurs as well-formed fine sized crystals or massive and granular. Its hardness is 6-6.5. It has a metallic luster and a dark red streak.


It occurs in fumaroles, as a result of combustion metamorphism and coal seam fires, in glass spherules related to meteorite impacts, and as accessory phase in kimberlites and carbonatites.[1]

It has been reported from Vesuvius and Stromboli, Italy.