9 Photos
Magnesioferrite
Chemical Formula	Mg(Fe3+)2O4
Species	Oxides & Hydroxides
Crystal System	Isometric
Mohs Scale	5-6
Specific Gravity	4.51
Color	Black to brownish black
Streak	Dark red
Luster	Metallic, Sub-Metallic
Refractive Index	n = 2.38
Diaphaneity	Opaque
Cleavage	On 111]
Fracture	Irregular/Uneven
Crystal Habit：As octahedral crystals, massive granular

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

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.

It has been reported from Vesuvius and Stromboli, Italy.