Wollastonite is a naturally occurring calcium silicate mineral with the molecular formula CaSiO3. Known as tabular spar in the late 1700s, it was named wollastonite in 1822 to honor the English chemist and natural philosopher William Hyde Wollaston. Wollastonite remained little more than a curiosity, however, until its first commercial use in 1933, when it was mined briefly in California as a raw material for the production of mineral wool. Wollastonite did not become an important industrial mineral until the 1950s, with growing appreciation of its value in coatings and ceramics during the post-war building boom.
Wollastonite is unique among nonmetallic industrial minerals for its combination of white color, acicular (needle-like) crystal shape and alkaline pH. Commercial grades are typically high in purity because most ores must be beneficiated by wet processing and/or high-intensity magnetic separation to remove accessory minerals. The accessory minerals most commonly associated with wollastonite are quartz, calcite (calcium carbonate), diopside (calcium magnesium silicate), garnet (calcium iron silicate, calcium aluminum silicate) and prehnite (calcium aluminum silicate).