Vishnevite

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

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]

References

  1. Fleischer, Michael & Mandarino, Joseph, "Glossary of Mineral Species", The Mineralogical Record, 1991
  2. Webmineral data
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