Wollastonite
| Colour | White |
|---|---|
| Mohs hardness | 4.5 to 5.0 |
| Lustre | Vitreous or dull to pearly on cleavage surfaces |
| Streak | White |
| Crystal system | Triclinic Monoclinic polytype exists |
| Transparency | Transparent to translucent |
| Cleavage | Perfect in two directions at near 90° |
| Fracture | Splintery to uneven |
| Chemical formula | Calcium metasilicate, CaSiO 3 |
| Specific gravity | 2.86–3.09 |
What is Wollastonite?
Wollastonite is a calcium inosilicate mineral (CaSiO3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolomite is subjected to high temperature and pressure, which sometimes occurs in the presence of silica-bearing fluids as in skarns or in contact with metamorphic rocks. Associated minerals include garnets, vesuvianite, diopside, tremolite, epidote, plagioclase feldspar, pyroxene and calcite. It is named after the English chemist and mineralogist William Hyde Wollaston (1766–1828).
How to identify Wollastonite
- Lustre: Vitreous or dull to pearly on cleavage surfaces.
- Hardness: Mohs 4.5 to 5.0 — soft; a knife will scratch it.
- Streak: White.
- Habit: Triclinic Monoclinic polytype exists crystal system.
Wollastonite in different forms
Stones often confused with Wollastonite
Frequently asked questions
How hard is Wollastonite?
Wollastonite is Mohs 4.5 to 5.0 on the hardness scale.
What colour is Wollastonite?
Wollastonite is typically white (White, colorless or gray).