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Browse Items (2 total)
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Mica, biotite
Formula
K2(Mg,Fe2+)6-4(Fe3+,Al,Ti)0-2[Si6-5Al2-3O20](OH,F)4
Structure
Sheet silicate
Crystal System
Crystal system: monoclinic (-)
Physical Properties
Colour in hand specimen: brown or black Cleavage: one, good Hardness: 2-3
Optical…
Mica, muscovite
Formula
K2Al4[Si6Al2O20](OH,F)4
Structure
Sheet silicate
Crystal System
Crystal system: monoclinic (-)
Physical Properties
Colour in hand specimen: colourless Cleavage: one, good Hardness: 2.5-3
Optical Properties
Colour in plane…