maghemite

Also known as IMA17-H

Maghemite (Fe2O3, γ-Fe2O3) is a member of the family of iron oxides. It has the same formula as hematite, but the same spinel ferrite structure as magnetite () and is also ferrimagnetic. It is sometimes spelled as "maghaemite".

Key facts

Mineral.name: Maghemite
Mineral.category: Oxide minerals
Mineral.image: Maghemite - Mineralogisches Museum Bonn.jpg
Mineral.imagesize: 260px
Mineral.formula: γ-Fe2O3
Mineral.IMAsymbol: Mgh
Mineral.strunz: 4.BB.15
Mineral.system: Cubic with a tetragonal supercell
Mineral.class: Gyroidal (432) (same H-M symbol)
Mineral.symmetry: P4132, P4332
Mineral.unit cell: a = 8.33 Å; Z = 8 or a = 8.35 Å c = 24.99 Å; Z = 8 for tetragonal supercell
Mineral.color: Brown, bluish black; brown to yellow in transmitted light; white to bluish gray in reflected light.
Mineral.habit: Rarely as minute octahedral crystals, or acicular overgrowths; commonly as coatings on or replacements of magnetite; massive.
Mineral.cleavage: None
Mineral.fracture: Subconchoidal
Mineral.mohs: 5
Mineral.luster: Dull
Mineral.streak: Brown

via Wikipedia infobox

Wikidata facts

Image: Maghemite - Mineralogisches Museum Bonn.jpg

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Strunz 8th edition (series ID, updated): IV/C.04c
Nickel-Strunz '10th ed', review of (9th ed/ 2009 update): 4.BB.15
Commons category: Maghemite
chemical formula: (Fe³⁺₀.₆₇☐₀.₃₃)Fe³⁺₂O₄
Nickel-Strunz 9th edition (updated 2009): 4.BB.15
Mohs' hardness: 6
IMA Mineral Symbol: Mgh

Sources (5)

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Article

6 sections

Contents

Occurrence
Cation distribution
Electronic structure
Applications
As pollutant
References

Maghemite can be considered as an Fe(II)-deficient magnetite with formula \left(\ce{Fe^{III}8}\right)_A\left[\ce{Fe^{III}_{40/3}\square_{8/3}}\right]_B\ce{O32} where \square represents a vacancy, A indicates tetrahedral and B octahedral positioning.