Constituent
Name
Nepheline
IMA name
Nepheline
Class
silicate mineral
Compound type
tektosilicate
Constituent abundance in material
Relevance
main - major
Arrangement
single phase
Mass fraction
1.0
Chemical composition
Formula
$Na_3K(Al_4Si_4O_{16})$
Chemical formula
Na3K(Al4Si4O16)
Elemental formula
Na3.126 K0.659 Al3.927 Si4.08 O16 Ba0.003 Mn0.002 Fe0.006 Ni0.001
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Na$ Sodium element 3.126 1.0 constituent element main
$K$ Potassium element 0.659 1.0 constituent element replacement
$Al$ Aluminium element 3.927 1.0 constituent element main
$Si$ Silicon element 4.08 1.0 constituent element main
$O$ Oxygen element 16 1.0 constituent element main
$Ba$ Barium element 0.003 1.0 constituent element replacement
$Mn$ Manganese element 0.002 1.0 constituent element replacement
$Fe$ Iron element 0.006 1.0 constituent element replacement
$Ni$ Nickel element 0.001 1.0 constituent element replacement
Composition comments
former formula: $(Na,K)AlSiO_4$ - Common Impurities: $Mg, Ca, H_2O$
Oxides
Formula $Na_{2}O$ $K_{2}O$ $FeO$ $SiO_{2}$ $CaO$ $MnO$ $Al_{2}O_{3}$ $NiO$ $BaO$
Mass fraction (%) 16.97 5.44 0.07 42.94 0.46 0.02 35.07 0.01 0.09

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
Molar mass
576.28 $g/mol$
Density
2.55 - 2.66 cal.: 2.64) $g/cm^3$
Refringence type
uniaxial
Refringence sign
negative
Birefringence
0.0030 - 0.0050
Refraction index $n_{\alpha}$
1.531 - 1.549
Refraction index $n_{\beta}$
1.528 - 1.544
Color
white, gray, brown, brownish gray, reddish white
Diaphaneity
transparent to opaque
Luster
vitreous