This Nepheline Syenite sample comes from East of Ledbeg, Sutherland, Scotland, and is part of the Borralan intrusion which lies in the SW corner of the Assynt region bordered by the Moine Thrust zone. The Birefringence range for Nepheline is from 0.0030 to 0.0050. Nepheline has a Uniaxial ( - ) optic axis. Nepheline Syenite is a proven performance enhancer in a broad range of paints, coatings, adhesives, sealants, plastics, and inks. It presents distinct cleavage, … Nepheline, also called nephelite (from Greek: νεφέλη, "cloud"), is a feldspathoid: a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites. Nepheline, is a feldspathoid: a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites. Refractory index values: nω = 1.529 – 1.546 . It is often associated with many minerals such as K-feldspar, Na-rich plagioclase, biotite, amphibole, zircon, and/or pyroxene. Nepheline crystals are rare and belong to the hexagonal system, usually having the form of a short, six-sided prism terminated by the basal plane. Fermion Index: Fermion Index = 0.0091968132 Boson Index = 0.9908031868 : Photoelectric: PE Nepheline = 2.13 barns/electron Nepheline … Nepheline Syenite is a proven performance enhancer in a broad range of paints, coatings, adhesives, sealants, plastics, and inks. syenite, foidite, and phonolite). Apatite is a very common mineral but transparent gemstone-quality is extremely rare. For detailed physical properties, see feldspathoid (table). nε = 1.526 – 1.542. Nepheline has a low surface relief. In some areas pyroxene is virtually absent, and it is replaced by a mixture of hornblende and biotite. This slide is mainly nepheline and K-feldspar, both in large and clear phenocrysts with interesting textures, with pleochroic aegirine and cancrinite. Excellent brightness, tint retention, … Phenocrysts of nepheline are more frequent than those of feldspar. Nepheline with a brilliant blue coating of Nosean-impregnated Sodalite comes from Sar-e-Sang, Kochka Valley, Badakshan Province, Afghanistan. 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 Comments: Barrel-shaped root-beer colored melilite crystal with clear nepheline. Location: ... Optical Properties of Melilite : Dichroism (e): colorless or light yellow. Calculated Properties of Nepheline : Electron Density: Bulk Density (Electron Density)=2.62 gm/cc note: Specific Gravity of Nepheline =2.66 gm/cc.