General Information:
Chemical Formula:(Fe++,Mg,Fe+++)5Al(Si3Al)O10(OH,O)8
Composition:(Molecular Weight = 664.18 gm)Magnesium 5.49 %
MgAluminum 8.12 %
AlIron 29.43 %
FeSilicon 12.69 %
SiHydrogen 0.91 %
H Oxygen 43.36 %
O Empirical Formula: Fe2+3Mg1.5Fe3+0.5Al2Si3O12(OH)6
Physical Properties: Cleavage:[???] Good
Color:green, greenish gray, or black.
Density:3.1 - 3.15, Average = 3.12
Diaphaniety:Transparent to Translucent
Hardness:2.5-3.5 - Finger Nail-Copper Penny
Luster:Pearly
Streak:greenish white
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