Maghemite

Maghemite
General
CategoryOxide minerals
Formula
(repeating unit)
γ-Fe2O3
IMA symbolMgh[1]
Strunz classification4.BB.15
Crystal systemCubic with a tetragonal supercell
Crystal classGyroidal (432)
(same H-M symbol)
Space groupP4132, P4332
Unit cella = 8.33 Å; Z = 8 or a = 8.35 Å c = 24.99 Å; Z = 8 for tetragonal supercell
Identification
ColorBrown, bluish black; brown to yellow in transmitted light; white to bluish gray in reflected light.
Crystal habitRarely as minute octahedral crystals, or acicular overgrowths; commonly as coatings on or replacements of magnetite; massive.
CleavageNone
FractureSubconchoidal
Mohs scale hardness5
LusterDull
StreakBrown
DiaphaneityOpaque, transparent in thin fragments
Specific gravity4.860 (calculated)
Optical propertiesIsotropic
Other characteristicsStrongly 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.

  1. ^ 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.
  2. ^ Mineralienatlas
  3. ^ 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.
  4. ^ Maghemite. Mindat
  5. ^ Maghemite. Webmineral
  6. ^ Cornell, R. M. and Schwertmann, Udo (2003) The Iron Oxides: Structure, Properties, Reactions, Occurrences and Uses. Wiley-VCH. p. 32. ISBN 3527302743.