Schäferite
Schäferite is a rare vanadate mineral with chemical formula Ca2NaMg2[VO4]3. Schäferite is isometric, which means that it has three axes of equal length and 90° angles between the axes.[4] Schäferite is isotropic, meaning that the velocity of light is the same no matter which direction the light passes through.[3]
| Schäferite | |
|---|---|
| General | |
| Category | Phosphate mineral Berzeliite group Garnet structural group |
| Formula (repeating unit) | Ca2NaMg2[VO4]3 |
| IMA symbol | Sfr[1] |
| 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 | [2][3] |
It was named after Helmut Schäfer (born 1931) who discovered it in a quarry on the Bellerberg Volcano in Germany.[2] It is found only in the Eifel Mountains volcanic area near Mayen, Laacher See district of Germany.[2] 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.[3]
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 Fur Mineralogie,1, 123-134.
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