Magnesioferrite: Properties and Occurrences

Magnesioferrite is a magnesium iron oxide mineral, a member of the magnetite series of spinels. It is the mineral magnesium iron oxide, a member of the magnetite (q.v.) series of spinels. It is a magnetic usually black mineral MgFe2O4 consisting of an oxide of magnesium and iron and constituting a member of the magnetite series

It is named after its chemical composition of magnesium and ferric iron.

General Information

  • Category: Oxide minerals (Spinel group )
  • Formula: Mg(Fe3+)2O4
  • Crystal system: Cubic
  • Crystal class: Hexoctahedral (m3m)
  • Color: Black to brownish-black.

Properties

Magnesioferrite crystallizes as black metallic octahedral crystals. It is a magnesium iron oxide mineral, a member of the magnetite series of spinels, which forms black metallic octahedral crystals. The density is 4.6 – 4.7 (average = 4.65), and the diaphaneity is opaque. Its hardness is 6-6.5. It has a metallic luster and a dark red streak.

  • 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

Occurrence

The magnesioferrite occurs as euhedral, frequently skeletal, micron-sized octahedral crystals. It occurs in fumaroles, as a result of combustion metamorphism and coal seam fires, in glass spherules related to meteorite impacts, and as an accessory phase in kimberlites and carbonatites. Occurs as well-formed fine sized crystals or massive and granular. It has been reported from Vesuvius and Stromboli, Italy.

Association: Hematite, titanian magnetite, ferrian diopside.

 

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