General Information:
Chemical Formula:
NaFe+++3Al6(BO3)3Si6O21F
Composition:
(Molecular Weight = 1,228.77 gm)
Sodium 1.87 % Na
Aluminum 13.17 % Al
Iron 13.63 % Fe
Silicon 13.71 % Si
Boron 5.28 % B
Oxygen 50.78 % O
Fluorine 1.55 % F
Empirical Formula:
NaFe3+3Al6(BO3)3Si6O21F
IMA Status:
Approved IMA 1966
Physical Properties:
Cleavage:
[???] Good
Color:
bronze, dark brown, or black.
Density:
3.31
Diaphaniety:
Translucent to Opaque
Hardness:
7 - Quartz
Streak:
yellowish brown
More details...