General Information: Chemical Formula:[ ]Na2(Mg3Al2)Si8O22(OH)2
Composition:(Molecular Weight = 783.54 gm)
Sodium 5.87 %
NaMagnesium 9.31 %
MgAluminum 6.89 %
AlSilicon 28.68 %
SiHydrogen 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
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