Wollastonite
47% CaO
50% SiO2
Primarily used as a secondary flux. An alternative source of calcium and is used in both earthenware and stoneware glazes.

The fibrous form of wollastonite can be very beneficial in bodies. In low-fired ceramics, Wollastonite reduces drying and firing shrinkage and warpage. It also promotes lower moisture and thermal expansion in the fired product and increases firing strength.