MAGHEMITE

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal system : Cubic
    Chemistry : Fe2O3
    Rarity : Quite common

This iron oxide, dimorphic from hematite, forms at low temperature in the oxidized surface zones of metal deposits. Maghemite comes from the oxidation of magnetite at low temperature or more rarely from the dehydration of lepidocrocite ; there is also a series of intermediate terms with magnetite of which it has the crystalline structure and strong magnetism. Its name is composed of the words magnetite and hematite, emphasizing the latter characteristic. Maghemite is a relatively common mineral constituting brown-black grainy to powdery masses, without clear crystals expressed (except in exceptional cases). It is an iron ore exploited at the same time as magnetite.

Main photo : Alluvial maghemite from the Carapooee gold mine, Victoria, Australia © Judy Rowe

Maghemite in the World

Maghemite is known in the magnetite deposits of the Bushveld (South Africa) and in numerous iron deposits, notably in Canada (Atikokan, Ontario), Brazil (Patos de Mina), and the United States (Iron Mountain, California) and in Japan (Ohinata).

Right photo : Maghemite pseudomorph after magnetite from Michelsberg, Germany © Volker Betz


Maghemite in France

In France, maghemite is reported in certain nickel mines in New Caledonia.

Twinning

No twin known for this mineral species, but can replace magnetite octahedra (pseudomorph).

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 6
Density : 4
Fracture : Undetermined
Streak : Brown

TP : Opaque
RI : -
Birefringence : 0
Optical character : None
Pleochroism : None
Fluorescence : None

Solubility : -

Magnetism : FerromagneticRadioactivity : None