Constituent
Name
Nepheline
IMA name
Nepheline
Class
silicate mineral
Compound type
tektosilicate
Formula
Na3K(Al4Si4O16)
Chemical formula
Na3K(Al4Si4O16)
Elemental formula
Na3 K Al4 Si4 O16
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
Na Sodium element 3 constituent element main
K Potassium element 1 constituent element main
Al Aluminium element 4 constituent element main
Si Silicon element 4 constituent element main
O Oxygen element 16 constituent element main
Composition comments
former formula: (Na,K)AlSiO4 - Common Impurities: Mg,Ca,H2O
Oxides
Formula Na2O K2O Al2O3 SiO2
Mass fraction (%) 15.91 8.06 34.9 41.13

Strunz

Class
silicates (09)
Division
tektosilicate without zeolitic H2O (09.F)
Family
without additional non-tetrahedral anions, (Al,B):Si = 1:1 (09.FA)
Code
09.FA.05

Dana

Major class
silicates (VIII)
Class
tectosilicate Al-Si framework (76)
Type
Feldspathoids and related species (76.02)
Group
Nepheline group (76.02.01)
Code
76.02.01.02
Phase type
crystalline
Crystal system
hexagonal
Crystal class
pyramidal
Crystal class symbol
6 (C6)
Crystal spacegroup
P6(3)
Comments
there are 3 cavities with oval outline and 1 cavity with hexagonal outline: the former are occupied by sodium, the latter by potassium
Texture
polycrystalline
Molar mass
584.33 g/mol
Density
2.55 - 2.66 cal.: 2.64) g/cm3
Refringence type
uniaxial
Refringence sign
negative
Birefringence
0.0030 - 0.0050
Refraction index nα
1.531 - 1.549
Refraction index nβ
1.528 - 1.544
Color
white, gray, brown, brownish gray, reddish white
Diaphaneity
transparent to opaque
Luster
vitreous