Zoisite is a mineral that has a secondary hydrothermal nature. The pink variety of zoisite is called thulite, the blue variety is called tanzanite.
You can see zoisite stone for sale and buy it in the Minerals of Russia online store.
General | |
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Category | Sorosilicate - epidote group |
Formula (repeating unit) |
Ca2Al3(SiO4)(Si2O7)O(OH) |
IMA symbol | Zo[1] |
Strunz classification | 9.BG.10 |
Dana classification | 58.2.1b.1 |
Crystal system | Orthorhombic |
Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
Space group | Pnma |
Identification | |
Color | White, gray, greenish brown, greenish gray, pink, blue, purple |
Crystal habit | Prismatic crystals with striations; massive to columnar |
Cleavage | Perfect {010} imperfect {100} |
Fracture | Uneven to conchoidal |
Mohs scale hardness | 6 to 7 |
Luster | Vitreous, pearly on cleavage surfaces |
Streak | White or colorless |
Diaphaneity | Transparent to translucent |
Specific gravity | 3.10–3.36 |
Optical properties | biaxial positive |
Refractive index | nα = 1.696 - 1.700 nβ = 1.696 - 1.702 nγ = 1.702 - 1.718 |
Birefringence | 0.006-0.018 |
Pleochroism | X = pale pink to red-violet; Y = nearly colorless to bright pink or deep blue; Z = pale yellow to yellow-green |
References | [2][3][4] |
Major varieties | |
Tanzanite | Gem-quality zoisite, blue-purple |
Thulite | Pink |