Kaliophilite

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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General Information:
 Chemical Formula:
KAlSiO4
 Composition:
(Molecular Weight = 158.16 gm)
Potassium 24.72 % K 
Aluminum 17.06 % Al
Silicon 17.76 % Si
Oxygen 40.46 % O 
 Empirical Formula:
KAlSiO4
 Locality:
Ejecta from Mte. Somma, Vesuvius.
Physical Properties:
 Cleavage:
[0001] Perfect
 Color:
colorless.
 Density:
2.49 - 2.67, Average = 2.58
 Diaphaniety:
Transparent to translucent
 Habits:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Acicular - Occurs as needle-like crystals.,
 Hardness:
5.5-6 - Knife Blade-Orthoclase
 Luster:
Vitreous - Greasy
 Streak:
white
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CALIOFILITE