| Maghemite | |
|---|---|
 | |
| General | |
| Category | Oxide minerals |
| Formula (repeating unit) | γ-Fe2O3 |
| IMA symbol | Mgh[1] |
| Strunz classification | 4.BB.15 |
| Crystal system | Cubic with a tetragonal supercell |
| Crystal class | Gyroidal (432) (same H-M symbol) |
| Space group | P4132, P4332 |
| Unit cell | a = 8.33 Å; Z = 8 or a = 8.35 Å c = 24.99 Å; Z = 8 for tetragonal supercell |
| Identification | |
| Color | Brown, bluish black; brown to yellow in transmitted light; white to bluish gray in reflected light. |
| Crystal habit | Rarely as minute octahedral crystals, or acicular overgrowths; commonly as coatings on or replacements of magnetite; massive. |
| Cleavage | None |
| Fracture | Subconchoidal |
| Mohs scale hardness | 5 |
| Luster | Dull |
| Streak | Brown |
| Diaphaneity | Opaque, transparent in thin fragments |
| Specific gravity | 4.860 (calculated) |
| Optical properties | Isotropic |
| Other characteristics | Strongly magnetic |
| References | [2][3][4][5] |
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 (Fe3O4) and is also ferrimagnetic. It is sometimes spelled as "maghaemite".
Maghemite can be considered as an Fe(II)-deficient magnetite with formula [6] where represents a vacancy, A indicates tetrahedral and B octahedral positioning.
![{\displaystyle \left({\ce {Fe^{III}8}}\right)_{A}\left[{\ce {Fe_{40/3}^{III}\square _{8/3}}}\right]_{B}{\ce {O32}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/797ed8ea95a1dfbedcb8667ed5cd71f0dac35ace)
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Mineralienatlas
- ^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1997). "Maghemite" (PDF). Handbook of Mineralogy. Vol. III (Halides, Hydroxides, Oxides). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209732.
- ^ Maghemite. Mindat
- ^ Maghemite. Webmineral
- ^ Cornell, R. M. and Schwertmann, Udo (2003) The Iron Oxides: Structure, Properties, Reactions, Occurrences and Uses. Wiley-VCH. p. 32. ISBN 3527302743.