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Nepheline

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Formula:
(Na,K)AlSiO4
System:
Hexagonal
Colour:
White, grey, yellowish
Hardness:
5½ - 6
Name:
From the Greek "nephele" for "cloud" since it turns cloudy when treated with strong acid.
A rock-forming mineral. Common in nepheline syenite, an igneous rock often found in alkaline complexes.

Compare the related kalsilite.

The presence of satellite reflections seems to be a universal property of nepheline (Vulić et al., 2011); most of 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

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
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
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Type Occurrence of Nepheline

Year of Discovery:
1801

Occurrences of Nepheline

Geological Setting:
Characteristic of alkaline igneous rocks.

Physical Properties of Nepheline

Vitreous, Greasy
Diaphaneity (Transparency):
Transparent, Opaque
Colour:
White, grey, yellowish
Comment:
Colored by inclusions also.
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)

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
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Nepheline no.9 - Goldschmidt (1913-1926)
3d models and HTML5 code kindly provided by www.smorf.nl.

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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.

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

Formula:
(Na,K)AlSiO4
Essential elements:
All elements listed in formula:
Common Impurities:
Mg,Ca,H2O

Relationship of Nepheline to other Species

9.FA.05KaliophiliteKAlSiO4
9.FA.05KalsiliteKAlSiO4
9.FA.05Panunzite(K,Na)AlSiO4
9.FA.05Trikalsilite(K,Na)AlSiO4
9.FA.05Yoshiokaite(Ca,Na)[Al(Al,Si)O4]
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,Al)Si2O8]
9.FA.30MicroclineKAlSi3O8
9.FA.30OrthoclaseKAlSi3O8
9.FA.30SanidineKAlSi3O8
9.FA.30Rubicline(Rb,K)AlSi3O8
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.35ReedmergneriteNa[BSi3O8]
9.FA.40ParacelsianBaAl2Si2O8
9.FA.45SvyatoslaviteCaAl2Si2O8
9.FA.45KumdykoliteNaAlSi3O8
9.FA.50Slawsonite(Sr,Ca)Al2Si2O8
9.FA.55LisetiteCaNa2Al4Si4O16
9.FA.60BanalsiteBaNa2[Al2Si2O8]2
9.FA.60StronalsiteSrNa2[Al2Si2O8]2
9.FA.65DanburiteCaB2Si2O8
9.FA.65MaleeviteBaB2Si2O8
9.FA.65PekoviteSrB2Si2O8
9.FA.70Lingunite(Na,Ca)AlSi3O8
9.FA.75KokchetaviteKAlSi3O8
16.4.2Panunzite(K,Na)AlSiO4
16.4.3Trikalsilite(K,Na)AlSiO4
16.4.4Anorthoclase(Na,K)AlSi3O8
16.4.5Naujakasite(Na,K)6(Fe2+,Mn2+,Ca)(Al,Fe)4Si8O26
16.4.6Montesommaite(K,Na)9Al9Si23O64 · 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.

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.

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.

Internet Links for Nepheline

Specimens:
The following Nepheline specimens are currently listed for sale on minfind.com.

Localities for Nepheline

map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
Mineral and/or Locality  
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