(Na,K)AlSiO4Hexagonal
Nepheline
(Na,K)AlSiO4
SilicatesChemical Formula(Na,K)AlSiO4
Crystal SystemHexagonal
Mohs Hardness6
Specific Gravity2.6
ColorColorless, white, gray, reddish
LusterVitreous to greasy
StreakWhite
CleavageTwo directions
FractureUneven
Occurrence
Found in silica-undersaturated igneous rocks. Component of nepheline syenite.