What Is Wollastonite ?

Wollastonite is a naturally-occurring, calcium metasilicate (CaSiO3) mineral with a theoretical composition of 48.3% CaO and 51.7% SiO2, and an acicular (needle-like) particle shape. It is usually white and can withstand temperatures up to 1540°C.


Wollastonite is formed when impure limestone or dolostone undergo high temperature and pressure changes, sometimes in the presence of silica-bearing fluids, as in skarns or contact metamorphic rocks.

Physical Properties

• High brightness
• Low moisture and oil absorption
• Low water solubility
• Basicity
• Low volatile content
• High melting point
• Acicular crystal structure
• Relatively high hardness (4.5 on Mohs’ scale)

Wollastonite Cluster

Principle Uses


Wollastonite improves flexural and impact strengths. It has found application as a substitute for asbestos in fire-resistant building products and is an excellent lightweight reinforcing filler for cement boards.

Paint & Coatings

Fine acicular particles act as a flattening agent and allows paint to settle with uniform thickness, better corrosion and barrier properties, and improve thermal stability at high temperatures. High brightness and whiteness reduce pigment load and typically very low oil absorption, reduces the volume of binder required and contributes to reduced pigment costs.


Wollastonite improves the durability of the composite due to its acicular structure. It also enhances electrical insulating properties, adds fire resistance, and improves dimensional stability, making it an ideal reinforcement in thermoplastics, engineering alloys, thermosets and elastomers. Wollastonite also improves knit/weld line strength and prevents splaying during injection moulding.

Adhesives & Sealings

Wollastonite is a highly effective functional filler in adhesive and sealant applications, including structural, high temperature, pressure sensitive, hot melt, heat activated and UV curable adhesives and sealants.


Wollastonite is used to improve physical properties in gaskets, belts, plugs, O-rings, seals and moulded parts.


Wollastonite can be used in a variety of ceramic applications including ceramic glazes and bodies, enamels, frits, fluxes and in sanitary-ware. This industrial mineral is a source of CaO to alkaline glaze formulations to improve the strength of the glaze .

Crushed End Product