Introduction to Wollastonite

Wollastonite is a naturally occurring calcium inosilicate mineral that has the chemical formula CaSiO3 and is formed by approximately equal proportions of CaO and SiO2. In some cases, wollastonite may contain small amounts of iron, magnesium, and manganese substituting for calcium.

The mineral is named after William Hyde Wollaston (1766 – 1822), a noted English chemist and mineralogist. Originally trained as a physician, in 1793 Wollaston left the practice of medicine to focus his efforts on scientific pursuits. Wollaston made important contributions in several fields: he was the discoverer of the elements palladium (Pd) and rhodium (Rh), and his work helped pave the way for the development of new inventions such as the electric motor and the camera. In recognition of his many accomplishments, Wollaston was named a Fellow of the Royal Society of London at the age of 27, and was awarded the Copley Medal, the Society’s oldest and most prestigious award, in 1802.

Wollastonite forms when impure limestone or dolostone is subjected to high pressure and temperature. It is usually white in colour, but may sometimes appear to have a cream, grey, or very pale green colour. Wollastonite has a triclinic crystal structure, and a melting point of 1540 ˚ C.

Wollastonite deposits are found in several regions of the world, most notably northeastern North America, Mexico, several Western European countries, and China. The mineral has several characteristics that make it commercially valuable, including its high brightness and whiteness, its low moisture and oil absorption properties, and its low volatile content. Because of these attributes, wollastonite is presently used in a variety of industrial applications, including ceramics, friction products, metallurgy, paint filler, and plastics.