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 | |
---|---|
Allgemein | |
Kategorie | 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
edit- ^ 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.
- ^ a b c Ralph, Jolyon and Ida Chau, 17 August 2010, "Schäferite." http://www.mindat.org/min-7279.html. Accessed 27 September 2010.
- ^ a b c 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.