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Product Benefits
Technical Details

Cristobalite (silica, chemical formula SiO2) is the result of the calcination of quartz at a temperature of 1500°C:


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Cristobalite can be characterised by:


  • High brightness
  • Relatively high Mohs hardness of 6.5
  • Relatively low refractive index, making it a transparent filler in various binders
  • Easy wetting
  • High inertness in various media
  • Transparency for UV-radiation (ie. suitable for UV-curing processes).


Note when using cristobalite: depending on the particle size distribution of the product, it can be labelled (STOT RE 2 or STOT RE 1). For more detailed information, visit


Basic properties

Property Value Unit
Moisture [%]
pH 9 [-]
Hardness (Mohs) 6.5 [-]
Refractive index 1.48 [-]
Colour (D65/ 10°) L* 98 [-]
Density 2.3 [kg/ dm3]


Product overview

Coarse Fine
Product Grade D50 Name Grade D50 D90 OA
[µm] [µm] [µm]
Sibelite M72 310 Sibelite M002 70 200 21
M72T (1) 300 M006 40 100 23
M0010 30 75 23.5
M3000 17 40 26
M3500 10 30 26
M4000 6 12 27
M6000 4 8 28

(1): Tamisé: > 500 µm = < 1%

Production locations Sibelite


Sibelite is the brand name for Sibelco’s cristobalite products.

The majority of the fine grades are labelled STOT RE 2 or STOT RE 1 due to the presence of fine crystalline silica.



  • Dirt pick-up resistance: the presence of cristobalite improves the coating’s resistance to dirt (from the atmosphere, for instance).
  • Ease of tinting: due to the combination of refractive index, brightness and colour, paints including cristobalite will provide excellent reproducible colour results when working with tinting systems.
  • Texture effect: the use of coarse cristobalite grades provide texture to the coating surface.
  • Tint retention: paints including cristobalite show improved tint retention over other minerals when subjected to natural weathering.
  • UV resistance and weatherability: due to its inertness, cristobalite supports good UV and weatherability performance to exterior architectural coatings.
  • Burnish resistance: due to its hardness of 6.5 on Mohs scale, cristobalite provides good burnish resistance (low tendency to become glossy when rubbed).
  • Gloss control: the gloss level of an interior coating can be regulated by selecting the appropriate grade of cristobalite.
  • Scrub resistance: due to its hardness of 6.5 on Mohs scale, cristobalite improves the wet-scrub resistance of interior decorative paints.
  • Stain resistance: cristobalite acts as a supporting mineral filler in stain resistant coatings.
  • Abrasion and scratch resistance: due to its fairly high hardness of 6.5 on Mohs scale, cristobalite provides abrasion and scratch resistance to the coating.
  • Chemical resistance: due to its inert nature, cristobalite  provides good chemical resistance compared to conventional fillers.
  • Clarity: due to its fairly low refractive index, cristobalite becomes transparent when combined with certain binder systems.
  • UV-curing compatibility: being transparent for UV radiation, cristobalite does not block the curing mechanism.
  • Brightness: being one of the fillers with the highest brightness, cristobalite contributes to the visibility of road marking paints.
  • Skid resistance: coarse cristobalite grades will give a roughness to the substrate, making it less slippery in general as well as in wet conditions, and provides better visibility in wet conditions.
  • IR reflection: cristobalite contributes to IR reflection of roof coatings.
  • Pore and grain filling properties (sealer): with low impact on the viscosity, cristobalite can be used as a mineral filler in sealers to give them more body.


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