A white nonmetallic natural mineral - calcium metasilicate, CaSiO3. It is a pure white mineral that is wholly acicular (needle-like crystals). Wollastonite is available in fine particle size powders. This material has a very unusual texture, it does not flow at all. 

Wollastonite exhibits a slight solubility in water, but slips containing it can become more alkaline. In casting bodies this can be a benefit, its gellation can decrease casting rates.

Wollastonite has the ability to seed crystals, and can be valuable to create special effects which depend on devitrification (crystallization during cooling). 

Wollastonite is also used in stain and frit formulations to supply CaO in a more easily melted form.