General Information:
Chemical Formula:
(Na,K)(Mg,Fe,Al)6(Si,Al)8O20(OH,F)4
Composition:
(Molecular Weight = 843.71 gm)
Potassium 1.16 % K
Sodium 2.04 % Na
Magnesium 10.37 % Mg
Aluminum 8.31 % Al
Iron 11.91 % Fe
Silicon 19.97 % Si
Hydrogen 0.36 % H
Oxygen 43.62 % O
Fluorine 2.25 % F
Empirical Formula:
Na0.75K0.25Mg3.6Fe2+1.8Al2.6Si6O20(OH)3F
IMA Status:
Approved IMA 1979
Physical Properties:
Cleavage:
[001] Perfect
Color:
yellow brown or dark brown.
Diaphaniety:
Transparent to Translucent
Hardness:
2.5-3 - Finger Nail-Calcite
Luster:
Vitreous (Glassy)
Streak:
white
More details...