Kalsilite

Kalsilite (KAlSiO4) is a vitreous white to grey feldspathoidal mineral that is found in some potassium-rich lavas, such as from Chamengo Crater in Uganda. It has a relative hardness of 5.5.See also: List of minerals
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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
Physical Properties:
 Cleavage:
[1010] Indistinct, [0001] Indistinct
 Color:
colorless, gray, gray white, or white.
 Density:
2.59 - 2.625, Average = 2.6
 Diaphaniety:
Transparent to Translucent
 Hardness:
6 - Orthoclase
 Luster:
Vitreous - Greasy
 Streak:
white
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KALSILITE