close box The applications which
can use this mineral are
highlighted. Please select
one to learn more.
Product Benefits
Technical Details

Feldspar (silicate, chemical formula Na(AlSi3O8), where Na can also be replaced by K) is one of the main constituents of the Earth’s crust. Feldspar can be characterised by:


  • Relatively high Mohs hardness of 6
  • Low electrical conductivity
  • Easy to wet
  • High inertness in various media.


And, depending on the grade:


  • Low content of lamellar mica (Unispar FF)
  • Low fine crystalline silica fraction (no labelling) (Unispar PG (W))
  • Whiteness (Unispar PG W).


Note when using feldspar: depending on the particle size distribution of certain products, they can be labelled STOT RE 2. For more detailed information, visit www.safesilica.eu.

Sibelco feldspar quarry in Cine (Turkey)


Basic properties

Property Value Unit
Moisture < 0.5 [%]
Hardness (Mohs) 6 (6.5) [-]
Refractive index 1.53 [-]
L.O.I. 0.5 [%]
Density 2.6 [kg/ dm3]



Product overview

Product Grade D50





[g/ 100 g]

pH L*
Feldspar FF-20 6 n.d. 32 9.8
FF-30 8 n.d. 28 9.7
FF-60 19 n.d. 27 9.5
FF-150 23 n.d. 24 9.4
PG4 4 17 26 9.5 94.5
PG W7 7 25 27 8.0 97.0
PG W13 13 60 22 8.1 96.4
PG W20 20 80 19 8.2 96.2

Production locations Feldspar



  • Ease of tinting: due to the combination of refractive index, brightness and colour, paints including cristobalite 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 on Mohs scale, feldspar 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 feldspar.
  • Scrub resistance: due to its hardness of 6 on Mohs scale, feldspar improves the wet-scrub resistance of interior decorative paints.
  • Stain resistance: feldspar acts as a supporting mineral filler in stain resistant coatings.
  • Abrasion and scratch resistance: due to its fairly high hardness of 6 on Mohs scale, feldspar provides abrasion and scratch resistance to the coating.
  • Chemical resistance: due to its inert nature, feldspar will provide good chemical resistance compared to conventional fillers.
  • Brightness: being a filler with a high brightness, feldspar (Unispar PG W) contributes to the visibility of road marking paints.
  • Pore and grain filling properties (sealer): with low impact on the viscosity, feldspar can be used as a mineral filler in sealers to give them more body.


Sibelco © 2024