Wollastonite is a mineral of the silicate class, which is distinguished by chemical purity and is formed during contact and deep metasomatism of limestones. May form large aggregations. It is used as a substitute for asbestos, ceramics production, metallurgy, etc. It was also used in the thermal protection of the Buran reusable spacecraft.
You can see wollastonite stone for sale and buy it in the Minerals of Russia online store.
General | |
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Category | Inosilicate mineral |
Formula (repeating unit) |
Calcium metasilicate, CaSiO3 |
IMA symbol | Wo |
Strunz classification | 9.DG.05 |
Crystal system | Triclinic Monoclinic polytype exists |
Crystal class | Pinacoidal (1) (same H-M symbol) |
Space group | P1 (1A polytype) |
Unit cell | a = 7.925 Å, b = 7.32 Å, c = 7.065 Å; α = 90.055°, β = 95.217°, γ = 103.42°; Z = 6 |
Identification | |
Formula mass | 116.159 g/mol |
Color | White, colorless or gray |
Crystal habit | Rare as tabular crystals—commonly massive in lamellar, radiating, compact and fibrous aggregates. |
Twinning | Common |
Cleavage | Perfect in two directions at near 90° |
Fracture | Splintery to uneven |
Mohs scale hardness | 4.5 to 5.0 |
Luster | Vitreous or dull to pearly on cleavage surfaces |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 2.86–3.09 |
Optical properties | Biaxial (-) |
Refractive index | nα = 1.616–1.640 nβ = 1.628–1.650 nγ = 1.631–1.653 |
Birefringence | δ = 0.015 max |
2V angle | Measured: 36° to 60° |
Melting point | 1540 °C |
Solubility | Soluble in HCl, insoluble in water |
Other characteristics | Heat of Formation (@298): -89.61kJ Gibbs Free Energy: 41.78kJ |