Nepheline

Nepheline is a rock-forming mineral. The formula of nepheline in some sources will list it as NaAlSiO4. It is usually massive and in unattractive specimens, though a handful of localities have produced well-crystallized examples of this mineral. Nepeheline is a primary constituent of nepheline syenite rocks and nepheline syenite pegmatites, forming in alkali-rich plutonic environments often together with a host of rare minerals.