Nepheline

Nepheline, also called nephelite (from Greek: nephos, "cloud"), is a feldspathoid: a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites. It is very occasionally found in mica schist and gneiss.Nepheline crystals are rare and belong to the hexagonal system, usually having the form of a short, six-sided prism terminated by the basal plane. The unsymmetrical etched figures produced artificially on the prism faces indicate, however, that the crystals are hemimorphic and tetartohedral, the only element of symmetry being a polar hexad axis. It is found in compact, granular aggregates, and can be white, yellow, gray, green, or even reddish (in the eleolite variety). The hardness is 5.5 - 6, and the specific gravity 2.56 - 2.66. It is often translucent with a greasy luster.
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Noun
1. a whitish mineral consisting of sodium aluminum silicate or potassium aluminum silicate in crystalline form; used in the manufacture of ceramics and enamels
(synonym) nephelite
(hypernym) mineral
(substance-holonym) nephelinite

(n.)
Alt. of Nephelite
  

General Information:
 Chemical Formula:
(Na,K)AlSiO4
 Composition:
(Molecular Weight = 146.08 gm)
Potassium 6.69 % K 
Sodium 11.80 % Na
Aluminum 18.47 % Al
Silicon 19.23 % Si
Oxygen 43.81 % O 
 Empirical Formula:
Na0.75K0.25Al(SiO4)
 Environment:
Silica-poor igneous rocks.
 Locality:
Magnet Cove, Magnet Cove, Ouachita Mountains, Hot
 Name Origin:
From the Greek nephele, "cloud," because it becomes clouded when put in strong acid.
Physical Properties:
 Cleavage:
[1010] Poor
 Color:
white, gray, brown, brownish gray, or reddish white.
 Density:
2.55 - 2.65, Average = 2.59
 Diaphaniety:
Transparent to translucent to opaque
 Habits:
Massive - Granular - Common texture observed in granite and other igneous rock., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).,
 Hardness:
6 - Orthoclase
 Luminescence:
None.
 Luster:
Vitreous - Greasy
 Streak:
white
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Eng: nepheline
Urdu: سنگِ سحابي؛ ايک دھات؛ سوڈيم کا ايک سِليکيٹ