Barrerite

General Information:
 Chemical Formula:
(Na,K,Ca)2Al2Si7O18·7(H2O)
 Composition:
(Molecular Weight = 694.19 gm)
Potassium 1.69 % K 
Sodium 1.99 % Na
Calcium 0.58 % Ca
Aluminum 7.77 % Al
Silicon 28.32 % Si
Hydrogen 2.03 % H 
Oxygen 57.62 % O 
 Empirical Formula:
Na0.6K0.3Ca0.1Al2Si7O18·7(H2O)
 IMA Status:
Approved IMA 1974
Physical Properties:
 Cleavage:
[???] Perfect
 Color:
white or pink.
 Density:
2.13
 Diaphaniety:
Transparent to Translucent
 Hardness:
3-4 - Calcite-Fluorite
 Luster:
Vitreous (Glassy)
 Streak:
white
More details...