General Information:
Chemical Formula:
[ ]Na2(Mg3Al2)Si8O22(OH)2
Composition:
(Molecular Weight = 783.54 gm)
Sodium 5.87 % Na
Magnesium 9.31 % Mg
Aluminum 6.89 % Al
Silicon 28.68 % Si
Hydrogen 0.26 % H
Oxygen 49.01 % O
Empirical Formula:
Na2Mg3Al2(Si8O22)(OH)2
Environment:
Metamorphic blue shists.
IMA Status:
Approved IMA 1978
Locality:
Common world wide.
Name Origin:
From the Greek glaukos - "blue" and fanos - "appearing."
Physical Properties:
Cleavage:
[110] Good, [001] Good
Color:
gray, bluish black, lavender blue, or azure blue.
Density:
3 - 3.15, Average = 3.07
Diaphaniety:
Translucent
Habits:
Massive - Fibrous - Distinctly fibrous fine-grained forms., Columnar - Forms columns, Granular - Generally occurs as anhedral to subhedral crystals in matrix.
Hardness:
6-6.5 - Orthoclase-Pyrite
Luminescence:
Non-fluorescent.
Luster:
Vitreous - Pearly
Streak:
grayish blue
More details...