Not to be confused with Nephrite or Nepheline syenite.
Nepheline
General
Category
Tectosilicate, feldspathoid
Formula (repeating unit)
(Na,K)AlSiO4
IMA symbol
Nph[1]
Strunz classification
9.FA.05
Crystal system
Hexagonal
Crystal class
Pyramidal (6) H–M symbol: (6)
Space group
P63
Identification
Formula mass
146.08 g/mol
Color
White, gray, brown, brownish gray, or reddish white
Crystal habit
Massive granular to prismatic
Twinning
On [1010], [3365], and [1122]
Cleavage
[1010] Poor
Fracture
Subconchoidal
Mohs scale hardness
6
Luster
Vitreous to greasy
Streak
White
Specific gravity
2.55–2.65 (average: 2.59)
Optical properties
Uniaxial (−)
Refractive index
nω = 1.529–1.546 nε = 1.526–1.542
Birefringence
δ = 0.003–0.004
Other characteristics
non-radioactive, non-magnetic, non-fluorescent
References
[2][3][4]
Nepheline, also called nephelite (from Ancient Greek νεφέλη (nephélē) 'cloud'), is a rock-forming mineral in the feldspathoid group – a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites. It is used in glass and ceramic manufacturing and other industries, and has been investigated as an ore of aluminium.
^Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Nepheline" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 13 August 2022.
^Nepheline, Mindat.org
^Barthelmy, David (2014). "Nepheline Mineral Data". Webmineral.com. Retrieved 13 August 2022.
Nepheline, also called nephelite (from Ancient Greek νεφέλη (nephélē) 'cloud'), is a rock-forming mineral in the feldspathoid group – a silica-undersaturated...
Nepheline syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or...
with <5% normative quartz Nepheline syenite – Holocrystalline plutonic rock – A silica-undersaturated plutonic rock of nepheline and alkali feldspar Nephelinite –...
melt is produced, forming a nepheline syenite, where orthoclase is replaced by a feldspathoid such as leucite, nepheline or analcime. Conversely in certain...
produce feldspars. In some cases, they may take other forms, such as nepheline, leucite, and muscovite, but in the great majority of instances they are...
syenite with significant nepheline present can be termed a nepheline-bearing syenite or nepheline syenite, with the term nepheline replaceable by any foid...
and nepheline, along with accessories including biotite, magnetite, ilmenite and analcime. Theralite is the intrusive equivalent of nepheline basanite...
igneous rock. It is a coarse-grained, foliated variety of nepheline syenite, sometimes called nepheline syenite gneiss or gneissic nepeheline syenite. Litchfieldite...
Ijolite is an igneous rock consisting essentially of nepheline and augite. Ijolite is a rare rock type of considerable importance from a mineralogical...
Kishangarh, 14% of the population is under 6 years of age. Kishangarh Nepheline Syenite is among the 32 National Geological Monuments in India notified...
is a fine-grained or aphanitic igneous rock made up almost entirely of nepheline and clinopyroxene (variety augite). If olivine is present, the rock may...
valuable minerals are calcium carbonate (limestone), building stone, nepheline syenite, olivine, iron, titanium, and nickel. In 2017, the Government...
alteration product of corundum and nepheline. It occurs with kaolinite, gibbsite and diaspore in bauxite deposits; and with nepheline, gibbsite, diaspore, natrolite...
are, in order from oldest to youngest, the Outer Coarse Syenite, the Nepheline Sodalite Syenite, the Fire Tower Syenite, the Garland Peak Syenite, the...
such as nepheline syenites. Its name alludes to its ready solubility in acid. Eudialyte was first described in 1819 for an occurrence in nepheline syenite...
texture. Mineral content is usually abundant feldspathoids (leucite or nepheline), plagioclase, and lesser alkali feldspar. Pyroxenes (clinopyroxenes)...
Greenland, the Illimaussaq alkaline complex consists of pegmatites such as nepheline, syenites (especially kakortokite or naujaite) and sodalite (sodalite-foya)...
between 3.2 and 3.4. This mineral commonly occurs in alkalic igneous rocks, nepheline syenites, carbonatites and pegmatites. It also appears in regionally metamorphosed...
surface exposures of the Beemerville Alkaline Complex consist of two large nepheline syenite plutons; a nearby diatreme (Rutan Hill); and several other nearby...
the rock. For example, a nepheline-bearing gabbro is a foid-bearing gabbro in which the most abundant feldspathoid is nepheline. Foid-bearing monzogabbro...
and the accessory minerals are olivine, magnetite, leucite, kalsilite, nepheline, and perovskite, the rock is sometimes called katungite. However, more...
operations are the mining and processing of mines and processes apatite-nepheline ore from the Khibiny deposit. Products are marketed locally and in Finland...
sunstone This article incorporates public domain material from Feldspar and nepheline syenite (PDF). United States Geological Survey. Warr, L.N. (2021). "IMA–CNMNC...
petrological name for a pyroxene-melanite bearing nepheline syenite variety which contains nepheline-alkali feldspar pseudomorphs interpreted to be after...
occurs in phonolites and related leucite- or nepheline-rich, silica-poor, igneous rocks; less commonly in nepheline-free extrusives and metamorphic rocks (marble)...
Eyjafjallajökull. An origin by fractionation from basanite through nepheline hawaiite to nepheline benmoreite has been demonstrated for a volcanic suite in the...
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