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Nepheline

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Formula:
NaAlSiO4
System:
Hexagonal
Colour:
White, grey, yellowish
Lustre:
Vitreous, Greasy
Hardness:
5½ - 6
Name:
From the Greek "nephele" for "cloud" since it turns cloudy when treated with strong acid.
Dimorph of:
A rock-forming mineral, and classed as a feldspathoid. Common in nepheline syenite, an igneous rock often found in alkaline complexes.

Likely polymorphous with so-called carnegieite and 'α-carnegieite'.

Compare the related kalsilite and 'UM1967-10-SiO:AlHNa', the latter being possibly a natural analogue of "nepheline hydrate".

The presence of satellite reflections seems to be a universal property of nepheline (Vulić et al., 2011); most samples show a practically complete Si-Al-ordering, but some exhibit disorder up to 20%.

Ebay Warning: Some dealers on Ebay are selling aragonite specimens as 'nepheline'. Avoid any orange-brown hexagonal clusters listed from China as they are not nepheline at all.

Visit gemdat.org for gemological information about Nepheline.


Classification of Nepheline

Approved, 'Grandfathered' (first described prior to 1959)
9.FA.05

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H2O
A : Tektosilicates without additional non-tetrahedral anions
76.2.1.2

76 : TECTOSILICATES Al-Si Framework
2 : Al-Si Framework Feldspathoids and related species
16.4.1

16 : Silicates Containing Aluminum and other Metals
4 : Aluminosilicates of Na and K

Physical Properties of Nepheline

Vitreous, Greasy
Diaphaneity (Transparency):
Transparent, Opaque
Colour:
White, grey, yellowish
Comment:
Coloured by inclusions as well.
Hardness (Mohs):
5½ - 6
Tenacity:
Brittle
Cleavage:
Poor/Indistinct
Poor on {1010}, {0001}
Fracture:
Sub-Conchoidal
Density:
2.55 - 2.66 g/cm3 (Measured)    2.64 g/cm3 (Calculated)

Optical Data of Nepheline

Type:
Uniaxial (-)
RI values:
nω = 1.529 - 1.546 nε = 1.526 - 1.542
Max Birefringence:
δ = 0.003 - 0.004
Image shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:
Low

Chemical Properties of Nepheline

IMA Formula:
NaAlSiO4
Elements listed in formula:
Common Impurities:
Mg,Ca,H2O

Crystallography of Nepheline

Crystal System:
Hexagonal
Class (H-M):
6 - Pyramidal
Space Group:
P63
Cell Parameters:
a = 9.993(2) Å, c = 8.374(3) Å
Ratio:
a:c = 1 : 0.838
Unit Cell Volume:
V 724.19 ų (Calculated from Unit Cell)
Z:
8
Morphology:
Stout prisms, granular, compact, massive
Twinning:
On {1010}, {3365}, {1122}

Crystallographic forms of Nepheline

Crystal Atlas:
Image Loading
Click on an icon to view
Nepheline no.9 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

Toggle
Edge Lines | Miller Indicies | Axes

Transparency
Opaque | Translucent | Transparent

View
Along a-axis | Along b-axis | Along c-axis | Start rotation | Stop rotation
X-Ray Powder Diffraction:
Image Loading

Radiation - Copper Kα
Data Set:
Data courtesy of RRUFF project at University of Arizona, used with permission.

Occurrences of Nepheline

Type Occurrence of Nepheline

Relationship of Nepheline to other Species

Other Members of Group:
Cancrinite GroupA large, structurally complex group of alumosilicates.
CarnegieiteNaAlSiO4
KalsiliteKAlSiO4
LeuciteK(AlSi2O6)
Sodalite GroupThe Sodalite group have sodalite stacking producing cubo-octahedral cages that contain the anions and cations which ...
TrinephelineNaAlSiO4
9.FA.05KaliophiliteKAlSiO4
9.FA.05KalsiliteKAlSiO4
9.FA.05PanunziteK3Na(AlSiO4)4
9.FA.05TrikalsiliteK2NaAl3(SiO4)3
9.FA.05YoshiokaiteCa1-x(Al,Si)2O4
9.FA.05MegakalsiliteKAlSiO4
9.FA.10MalinkoiteNaBSiO4
9.FA.15VirgiliteLiAlSi2O6
9.FA.25LisitsyniteKBSi2O6
9.FA.30AdulariaKAlSi3O8
9.FA.30Anorthoclase(Na,K)AlSi3O8
9.FA.30Buddingtonite(NH4)AlSi3O8
9.FA.30CelsianBaAl2Si2O8
9.FA.30Hyalophane(K,Ba)(Al,Si)4O8
9.FA.30MicroclineKAlSi3O8
9.FA.30OrthoclaseKAlSi3O8
9.FA.30SanidineKAlSi3O8
9.FA.30RubiclineRbAlSi3O8
9.FA.30MonalbiteNaAlSi3O8
9.FA.35AlbiteNaAlSi3O8
9.FA.35Andesine(Na,Ca)[Al(Si,Al)Si2O8]
9.FA.35AnorthiteCaAl2Si2O8
9.FA.35Bytownite(Ca,Na)[Al(Al,Si)Si2O8]
9.FA.35Labradorite(Ca,Na)[Al(Al,Si)Si2O8]
9.FA.35Oligoclase(Na,Ca)[Al(Si,Al)Si2O8]
9.FA.35ReedmergneriteNaBSi3O8
9.FA.40ParacelsianBaAl2Si2O8
9.FA.45SvyatoslaviteCaAl2Si2O8
9.FA.45KumdykoliteNaAlSi3O8
9.FA.50SlawsoniteSrAl2Si2O8
9.FA.55LisetiteNa2CaAl4(SiO4)4
9.FA.60BanalsiteNa2BaAl4Si4O16
9.FA.60StronalsiteNa2SrAl4Si4O16
9.FA.65DanburiteCaB2Si2O8
9.FA.65MaleeviteBaB2Si2O8
9.FA.65PekoviteSrB2Si2O8
9.FA.70LinguniteNaAlSi3O8
9.FA.75KokchetaviteKAlSi3O8
16.4.2PanunziteK3Na(AlSiO4)4
16.4.3TrikalsiliteK2NaAl3(SiO4)3
16.4.4Anorthoclase(Na,K)AlSi3O8
16.4.5NaujakasiteNa6Fe2+Al4Si8O26
16.4.6MontesommaiteK9(Si23Al9)O64 · 10H2O

Other Names for Nepheline

Name in Other Languages:

Other Information

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Nepheline in petrology

An essential component of (items highlighted in red)
Common component of (items highlighted in red)
Accessory component of (items highlighted in red)

References for Nepheline

Reference List:
Klaproth, M.H. (1810): Chemische Untersuchung des Elaeoliths. Beiträge zur chemischen Kenntniss der Mineralkörper, Fünfter Band, Rottmann Berlin, 176-179

American Mineralogist (1972): 57: 1711-1719.

Bulletin de la Société française de Minéralogie et de Cristallographie (1984): 107: 499.

Mineralogical Record (1990): 21: 235-248.

Blancher, S.B.; D'Arco, P.; Fonteilles, M.; Pascal, M.L. (2010): Evolution of nepheline from mafic to highly differentiated members of the alkaline series: the Messum complex, Namibia. Mineralogical Magazine 74, 415-432.

Rastsvetaeva, R.K., Aksenov, S.M., Chukanov, N.V. (2010): Disordering of Al and Si in nepheline from Graulai (Germany). Doklady Chemistry, 435, 339-342.

Friese, K., Grzechnik, A., Petrícek, V., Schönleber, A., van Smaalen, S., Morgenroth, W. (2011): Modulated structure of nepheline. Acta Crystallographica, B67, 18-29.

Vulić, P., Balić-Žunić, T., Belmonte, L.J., Kahlenberg, V. (2011): Crystal chemistry of nephelines from ijolites and nepheline-rich pegmatites: influence of composition and genesis on the crystal structure investigated by X-ray diffraction. Mineralogy and Petrology, 101, 185-194.

Deshkar, A. et al.: Understanding the structural origin of crystalline phase transformations in nepheline (NaAlSiO4)-based glass-ceramics. Journal of the American Ceramic Society, in press (2017).

Internet Links for Nepheline

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https://www.mindat.org/min-2880.html
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Specimens:
The following Nepheline specimens are currently listed for sale on minfind.com.

Localities for Nepheline

Mineral and/or Locality  
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