Minerals explained 60

Nepheline (and its rarer potassium analogue: kalsilite) is a sodium‐rich, rock‐forming mineral belonging (like the feldspars and quartz) to the tectosilicates, which are 3‐dimensional structures made up of SiO 4 4− tetrahedra. Relatively rare compared to the feldspars, nepheline is an important mineral in the alkaline igneous rocks, such as nepheline syenites, phonolites and nephelinites. In silica‐deficient magmas, the natural endpoint of crystal fractionation is nepheline syenite just as silica‐rich magmas end at the granite minimum. Nepheline has commercial uses in the glass and ceramic industries and even as a raw material for aluminium production.