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Product Description
Benefits & Application Details


Sibelco feldspar quarry in Cine (Turkey)


Feldspar is an aluminium silicate with chemical formula X(AlSi3O8), where X can be Na, K, and a wide variety of other metals. Na(AlSi3O8) 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 
  • Low fine crystaline silica fraction (no labelling)
  • Whiteness


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.


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]



Feldspar products are also used as an extending filler in resin systems and because of the their low electrical conductivity quite often used in the elastomeric materials for high voltage insulators. 

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