Rubber / Rubber Compounding / Nepheline Syenite

Nepheline Syenite

Mineral:  Nepheline syenite (silicate, naturally occurring blend of albite, microcline and nepheline).


Nepheline syenite can be characterised by:

  • High purity
  • Absence free crystalline silica (free of labelling)
  • Brightness
  • Relatively low refractive index, making it a transparent filler in various binders
  • High inertness in various media
  • Easy wetting
  • Transparency for UV-radiation (i.e. suitable for UV-curing processes)


Basic properties

Property Value Unit
Hardness (Mohs) 6 [-]
Refractive index 1.51 – 1.53 [-]
Density 2.6 [kg/ dm3]


Product overview Nepheline

Product Grade D50





[g/ 100 g]





Nepheline S7 PO 4.3 85.4 23 10.4 0.2
S10 PO 1.9 85.6 31 10.4 0.4


Production location: Stjernoy (NO)


Advantage over quartz and cristobalite and certain feldspar grades: nepheline syenite grades are free of labelling, and can therefore be used as an alternative when labelled grades of other mineral fillers are no longer allowed or wanted.

Functionalities: Mechanical reinforcement, Durability

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