Greigite

Greigite
Greigite structure, SFe4 tetrahedra
General
CategorySulfide mineral
Thiospinel group
Spinel structural group
Formula
(repeating unit)
Fe2+Fe3+2S4
IMA symbolGrg[1]
Strunz classification2.DA.05
Crystal systemCubic
Crystal classHexoctahedral (m3m)
H-M symbol: (4/m 3 2/m)
Space groupFd3m
Unit cella = 9.876 Å; Z = 8
Identification
ColorPale pink, tarnishes to metallic blue-black
Crystal habitSpheres of intergrown octahedra and as disseminated microscopic grains
Mohs scale hardness4 to 4.5
LusterMetallic to earthy
DiaphaneityOpaque
Specific gravity4.049
Other characteristicsStrongly magnetic
References[2][3][4]

Greigite is an iron sulfide mineral with the chemical formula Fe2+Fe3+2S4. It is the sulfur equivalent of the iron oxide magnetite (Fe3O4). It was first described in 1964 for an occurrence in San Bernardino County, California, and named after the mineralogist and physical chemist Joseph W. Greig (1895–1977).[4][5]

  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. ^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1990). "Greigite" (PDF). Handbook of Mineralogy. Vol. I (Elements, Sulfides, Sulfosalts). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209708. Retrieved December 5, 2011.
  3. ^ Greigite. Mindat.org
  4. ^ a b Greigite. Webmineral
  5. ^ Skinner, Brian J.; Erd, Richard C.; Grimaldi, Frank S. (1964). "Greigite, the thio-spinel of iron; a new mineral" (PDF). American Mineralogist. 49: 543–55.