Maghemite Locality: Gara Djebilet, Algeria , North Africa Exposed in the Mineralogical Museum of University Bonn, Germany — Photo: Ra'ike · CC BY-SA 3.0
Maghemite
The γ-form of iron oxide — hematite's composition in magnetite's spinel structure, and magnetic to boot.
Intro adapted from Wikipedia (CC BY-SA).
Maghemite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula (Fe³⁺₀.₆₇ ₀.₃₃)Fe³⁺₂O₄.
It crystallizes in the cubic crystal system (space group Fd3m). It is a member of the Spinel structural group.
Key properties: Mohs hardness 5; specific gravity 4.86; Brown streak; submetallic luster; optically isotropic.
IMA symbol Mgh, IMA status: approved, named in 1927.
Formed by weathering or low-temperature oxidation of spinels containing ferrous iron, commonly magnetite or titanian magnetite. A widespread yellow pigment in continental sediments, rocks, and soils.
It is found associated with Magnetite, ilmenite, anatase, pyrite, marcasite, lepidocrocite, goethite.
The name comes from MAGnetite and HEMatite, in allusion to the mineral’s magnetism and composition.