Schäferite
Rare vanadate mineral
From Wikipedia, the free encyclopedia
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]
CategoryPhosphate mineral
Berzeliite group
Garnet structural group
Berzeliite group
Garnet structural group
FormulaCa2NaMg2[VO4]3
Strunz classification8.AC.25
| Schäferite | |
|---|---|
Orange micro crystals of Schäferite | |
| General | |
| Category | Phosphate mineral Berzeliite group Garnet structural group |
| Formula | 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]
