Karlite

General Information:
 Chemical Formula:
(Mg,Al)6(BO3)3(OH,Cl)4
 Composition:
(Molecular Weight = 589.17 gm)
Magnesium 18.56 % Mg
Aluminum 6.87 % Al
Boron 11.01 % B 
Hydrogen 0.51 % H 
Chlorine 6.02 % Cl
Oxygen 57.03 % O 
 Empirical Formula:
Mg4.5Al1.5BO33(OH)3Cl
 IMA Status:
Approved IMA 1980
Physical Properties:
 Cleavage:
[001] Perfect
 Color:
light green or silky white.
 Density:
2.8 - 2.85, Average = 2.82
 Hardness:
5.5 - Knife Blade
 Luster:
Silky
 Streak:
white
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