Vishnevite
Vishnevite, or sulfatic cancrinite, is a mineral of the cancrinite group with the chemical formula (Na, Ca, K)6(Si, Al)12O24[(SO4),(CO3), Cl2]2-4·nH2O. It has hexagonal crystals.[1][2]
| Vishnevite | |
|---|---|
 Vishnevite from Scotland | |
| General | |
| Category | Tectosilicate |
| Formula (repeating unit) | (Na,Ca,K)6(Si,Al)12O24[(SO4),(CO3),Cl2]2-4·nH2O |
| Strunz classification | 9.FB.05 |
| Crystal system | Hexagonal |
| Crystal class | Pyramidal (6) H-M symbol: (6) |
| Space group | P63 |
| Unit cell | a = 12.7228(3) c = 5.198(3) [Å]; Z = 1 |
| Identification | |
| Color | Colorless, light blue, orange-yellow, white |
| Cleavage | Perfect |
| Mohs scale hardness | 5 - 6 |
| Luster | Vitreous, pearly |
| Streak | White |
| Optical properties | Uniaxial (-) |
| Refractive index | nω = 1.490 - 1.507 nε = 1.488 - 1.495 |
| Birefringence | δ = 0.002 - 0.012 |
References
- Fleischer, Michael & Mandarino, Joseph, "Glossary of Mineral Species", The Mineralogical Record, 1991
- Webmineral data
External links
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