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Product Description
Benefits & Application Details


Wollastonite (calcium silicate, chemical formula CaSiO3) exists in an acicular and non-acicular form.

Wollastonite can be characterised by:

  • Shape (non-acicular/ acicular)
  • Medium Mohs hardness of 5
  • Alkaline nature.


Basic properties

Property Casiflux F/ FG Casiflux G Unit
Shape fibrous blocky
Moisture < 0.2 < 0.2 [%]
pH 10 10 [-]
Hardness (Mohs) 5 5 [-]
Refractive index 1.63 1.63 [-]
L.O.I. 3.5 3.5 [%]
Density 2.9 2.9 [kg/ dm3]

Casiflux is the product name for Sibelco’s wollastonite products.

  • Acicular grades are named Casiflux F or Casiflux FG
  • Granular grades are named Casiflux G 


Product Grade D50



[g/ 100 g]

Casiflux FG20 18 54 94
F75 28 59 90
G20 10.5 30 96
G38 18 28 96



Reinforcement due to acicular shape e.g. improving impact resistance and Flex Strength of PP-resins. 


Abrasion resistance: due to its hardness of 5 on Mohs scale, wollastonite will increase wear resistance. 


Rheology control in e.g. sealants and adhesives: due to its acicular shape, wollastonite has an impact on the rheology profile. When applying shear, the acicular particles will align and provide a low viscosity. When shear is removed, the acicular particles lose their orientation and cause the viscosity to increase above the level expected when the particles had a non-acicular shape.

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