Constituent
- Name
- Nepheline
- IMA name
- Nepheline
- Class
- silicate mineral
- Compound type
- tektosilicate
- Relevance
- main - major
- Arrangement
- heterogeneous in multi-phases
- Mass fraction
- 7.94
- Formula
- $Na_3K(Al_4Si_4O_{16})$
- Chemical formula
- Na3K(Al4Si4O16)
- Elemental formula
- Na3 K Al4 Si4 O16
- Isotope mixture type
- terrestrial abundance
- Composition comments
- former formula: $(Na,K)AlSiO_4$ - Common Impurities: $Mg, Ca, H_2O$
- Oxides
-
Formula $Na_{2}O$ $K_{2}O$ $Al_{2}O_{3}$ $SiO_{2}$ Mass fraction (%) 15.91 8.06 34.9 41.13
Strunz
- Class
- silicates (09)
- Division
- tektosilicate without zeolitic H2O (09.F)
- Family
- Tektosilicates 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) $g/cm^3$
- 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