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 %
NaMagnesium 10.37 %
MgAluminum 8.31 %
AlIron 11.91 %
FeSilicon 19.97 %
SiHydrogen 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
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