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Nepheline syenite: for glass and ceramics industry

  • Nepheline syenite is a deep magmatic rock (plutonite).
    The main constituents are: Nepheline, sodium and potassium feldspars. 

  • Nepheline syenite consists mainly of alkali feldspar (about 70-75%) and nepheline (about 20-25%).

  • Nepheline is a so-called feldspar representative (feldspatoid, minerals, with silica deficiency), therefore it does not contain crystalline quartz portion and is chemically inert.

  • This rock is a perfect substitute for feldspars, which are usually used in the ceramics and glass industry.

  • Nepheline syenite is used in 70% of the production of flat glass, fiberglass, milk glass, borosilicate glass and glassware. The largest application is in the production of glass containers.

  • In glass production, the aluminum oxide contained in the mineral delays devitrification of the final products.

  • 20-25% of nepheline syenite is used in the ceramics industry.

  • Our nepheline syenite comes from our own quarry in Kirsehir/Central Anatolia and is especially suitable for the production of tiles. 

  • Long-term availability is guaranteed by large reserves.

Nephelinsyenite- Quarry

Nepheline syenite (foid, feldspathoid, feldspar representative)


Feldspar representatives (foids), such as nepheline, are formed when the silicon in the residual melt runs out during feldspar formation. Rocks with feldspar representatives therefore basically contain no (very little) crystalline quartz.

NS is a raw material rich in Na2O, it lowers the melting point in glazes because the mineral easily forms eutectic mixtures, or formulated differently: It lowers the melting temperature in the melt because it reacts with the quartz it contains and has a wide melting interval 1060-1230°C. NS is also a raw material saver because, compared to feldspar, less quantity of it is needed in the compositions (melts) to produce the desired results. It thus acts as a high quality feldspar substitute in melts and ceramic bodies.
In ceramic bodies, it serves as a leavening agent before firing, as
a flux in sanitary ceramics, in floor and wall tiles, and in hard stone bodies. Again, the advantage is that NS has a lower melting point than sodium feldspar and therefore requires a shorter firing time and less energy input.

However, each industry has different requirements for nepheline syenite quality. Selection criteria for this, in addition to the price of the material, can be its color, iron oxide content, grading curve, and other factors. 

There exist worldwide, depending on the "impurities" in the mineral, very many color variations, from white, yellowish, gray, anthracite, green, blue, beige to brown, of nepheline syenite. The color spectrum of our raw nepheline syenite, due to hematite impurities, is in the golden yellow-beige-brown range.

The Mohs hardness of the NS is between 6 and 6.5, the bulk density between 60-1100 kg/m³, the specific gravity at 2.5-2.7 g/cm³ and the SiO2 content between 60-70%.


  • Analogous to feldspar, our nepheline syenite is used as a flux for tiles, enamels and in stained glass production.

  • Filler for plastics, paper, paints and varnishes and foams.

  • Chemical industry

  • Glass industry

  • Ceramic industry

  • low refractive index 1.53-1.5

  • high chemical resistance

  • In glass production, the alumina in NS, delays devitrification of the final product.

  • In ceramic products, it increases the durability and inertness.

Chemical parameters  (Raw-NS-avarage values)


SiO2           65-66 %

AlO2          16,5-19%

Na2O         4,0-5,5 %

K2O           6,0-7,5%

Fe2O3       1,5-2,5 %

Our nepheline syenite is chemically similar
(standard geochemical sample), strongly similar to the USGS/STM1 nepheline syenite standard. 

    Characteristics             Unit/Remark

  • Specific gravity:           2.55-2.76 kg/m³

  • Color:                           beige-brown

  • MOHS Hardness:         6-6.5

  • Melting point: approx. 1200-1450 °C

  • Grain shape:                sandy, chippy

  • Standard grain sizes:  on request

  • Special grain sizes:     on request

  • Packaging: big bag, bulk material

  • Reach: no registration obligation; acc. to EC No. 1907/2006

  • CAS No.:                     37244-96-5

  • Hazardous material:    No

All information provided here is for general and non-binding information only, without any claim to correctness and completeness and without warranty. Furthermore, they do not represent any general assurance of product properties.

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