General Information:
Chemical Formula:
(Fe++,Mg)2Al4Si5O18
Composition:
(Molecular Weight = 632.27 gm)
Magnesium 1.92 % Mg
Aluminum 17.07 % Al
Iron 13.25 % Fe
Silicon 22.21 % Si
Oxygen 45.55 % O
Empirical Formula:
Fe2+1.5Mg0.5Al4Si5O18
Environment:
Pegmatitic rocks.
IMA Status:
Approved IMA 1975
Locality:
Kolni Bory, Czechoslovakia.
Name Origin:
Named after the Czechoslovakian mineralogist, J. Sekanina (1901-1986).
Physical Properties:
Cleavage:
[100] Good
Color:
blue, blue violet, violet blue, or gray blue.
Density:
2.77
Diaphaniety:
Transparent to translucent
Habits:
Crystalline - Fine - Occurs as well-formed fine sized crystals., ,
Hardness:
7.5 - Garnet
Luminescence:
Non-fluorescent.
Luster:
Vitreous (Glassy)
Streak:
white
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