Welcome to Imerys Performance Minerals


What is Wollastonite?

wollastonite SEM

Wollastonite is a naturally occurring, calcium metasilicate (CaSiO3) mineral with a 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

SEM photograph Wollastonite
  • 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)
  • Adhesives and Sealants
  • Ceramics
  • Building Products
  • Paint and Coatings
  • Plastics
  • Rubber
  • Adhesives and Sealants

    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.

  • Ceramics

    • Due to its chemical composition, wollastonite acts as a natural frit, has a low loss on ignition and lowers CO2 emissions.
    • It is a used as a cost-effective reinforcement for advanced ceramics, whitewares and structural clay bodies.
    wollastonite sanitaryware
  • Building Products

    • Wollastonite is an excellent lightweight reinforcing filler for cement boards, fiber-cement boards and fire resistant insulating boards.
    • It brings a number of benefits in fiber-reinforced concrete.
    Wollastonite plasterboard
  • Paint and Coatings

    Wollastonite allows formulators to improve the cohesive strength of their coatings to obtain better corrosion and barrier properties, extend in-can stability and improve thermal stability at high temperatures. It has a low binder demand, low viscosity build and can easily be incorporated into both waterborne and solvent borne systems.

    wollastonite paints
  • Plastics

    Wollastonite’s reinforcing properties, thermal stability, low resin demand and chemical purity make it an ideal reinforcement in thermoplastics, engineering alloys, thermosets and elastomers. Wollastonite also improves knit/weld line strength, prevents splaying during injection molding, and provides enhanced fire resistance characteristics in compounds.

    wollastonite plastics
  • Rubber

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

    wollastonite rubber