Class : Silicates
    Subclass : Inosilicates
    Crystal system : Triclinic
    Chemistry : CaSiO₃
    Rarity : Fairly common to common

Wollastonite is a silicate characteristic of siliceous limestones transformed by contact metamorphism, skarns, and more rarely alkaline complexes. It has two polymorphs, pseudowollastonite and parawollastonite. Its composition is usually constant, although iron and manganese can replace part of the calcium. It was named in honor of the English chemist and mineralogist William Hyde Wollaston who discovered palladium and rhodium in 1804. Wollastonite forms masses of very elongated and often prickly acicular to lamellar crystals, commonly grouped in rosettes. Its color is white, its luster vitreous to pearly, sometimes straw yellow or pale greenish. Automorphic crystals are rare : they are more or less elongated prismatic individuals (up to 20 cm), or tabular parallel to {001} or {100}. It is a mineral quite widely used in the manufacture of tiles, ceramics, in metallurgy, in papermaking and as a material for the manufacture of electrical insulators.

Main photo : Wollastonite from Diana, New York, USA © Terry Burtzlaff

No twinning known for this mineral species.

No fakes listed for this mineral species.