Magnesioferrite

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Magnesioferrite
Magnesioferrite - Ochtendung, Eifel, Germany.jpg
Magnesioferrite from Ochtendung, Eifel, Germany
General
CategoryOxide minerals
Spinel group
Spinel structural group
Formula
(repeating unit)
Mg(Fe3+)2O4
Strunz classification4.BB.05
Crystal systemCubic
Crystal classHexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space groupFd3m
Unit cella = 8.3866 Å; Z = 8
Identification
ColorBlack to brownish black
Crystal habitAs octahedral crystals, massive granular
TwinningTwin plane {111}, contact twins
CleavageOn {111}
FractureUneven
TenacityBrittle
Mohs scale hardness6 - 6.5
LusterMetallic, semimetallic, dull
StreakDark red
DiaphaneityOpaque, transparent in thin fragments
Specific gravity4.55 – 4.65 measured
Optical propertiesIsotropic
Refractive indexn = 2.38
Other characteristicsMagnetic
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.

Occurrence[edit]

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.

References[edit]