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| Greigite | |
|---|---|
 Greigite structure, SFe4 tetrahedra | |
| General | |
| Category | Sulfide mineral Thiospinel group Spinel structural group |
| Formula (repeating unit) | Fe2+Fe3+2S4 |
| IMA symbol | Grg[1] |
| Strunz classification | 2.DA.05 |
| Crystal system | Cubic |
| Crystal class | Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m) |
| Space group | Fd3m |
| Unit cell | a = 9.876 Å; Z = 8 |
| Identification | |
| Color | Pale pink, tarnishes to metallic blue-black |
| Crystal habit | Spheres of intergrown octahedra and as disseminated microscopic grains |
| Mohs scale hardness | 4 to 4.5 |
| Luster | Metallic to earthy |
| Diaphaneity | Opaque |
| Specific gravity | 4.049 |
| Other characteristics | Strongly 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]
- ^ 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.
- ^ 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.
- ^ Greigite. Mindat.org
- ^ a b Greigite. Webmineral
- ^ 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.