| Schäferite | |
|---|---|
| General | |
| Category | Phosphate mineral Berzeliite group Garnet structural group |
| Formula (repeating unit) | Ca2NaMg23 |
| IMA symbol | Sfr |
| Strunz classification | 8.AC.25 |
| Crystal system | Cubic |
| Crystal class | Hexoctahedral (m3m) H-M symbol: (4/m 3 2/m) |
| Space group | Ia3d |
| Unit cell | a = 12.427 Å, Z = 8 |
| Identification | |
| Formula mass | 496.57 g/mol |
| Color | Red, orange-red |
| Crystal habit | Octahedral crystals |
| Cleavage | None |
| Fracture | Conchoidal |
| Mohs scale hardness | 5 |
| Luster | Vitreous |
| Streak | Yellow |
| Diaphaneity | Transparent |
| Optical properties | Isotropic |
| Refractive index | n = 1.96 |
| References | |
Schäferite is a rare vanadate mineral with chemical formula Ca2NaMg23. Schäferite is isometric, which means that it has three axes of equal length and 90° angles between the axes. Schäferite is isotropic, meaning that the velocity of light is the same no matter which direction the light passes through.
It was named after Helmut Schäfer (born 1931) who discovered it in a quarry on the Bellerberg Volcano in Germany. It is found only in the Eifel Mountains volcanic area near Mayen, Laacher See district of Germany. It occurs within a xenolith in a leucite tephrite. It is the magnesium analogue of palenzonaite and is a member of the garnet structural group.
References
- 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.
- ^ Ralph, Jolyon and Ida Chau, 17 August 2010, "Schäferite." http://www.mindat.org/min-7279.html. Accessed 27 September 2010.
- ^ Barthelmy, David, 1997-2010, “Schäferite Mineral Data.” http://www.webmineral.com/data/Schaferite.shtml. Accessed 27 September 2010.
- Verlagsbuchhandlung, E.S. (1999) Schäferite, a new vanadium garnet. Neues Jahrbuch für Mineralogie,1, 123-134.
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