Mineral 1.0: Biotite

Mineral 1.0

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BiotiteK(Mg,Fe)₃(AlSi₃O₁₀)(OH)₂

Class: Silicate
Subclass: Phyllosilicate
Hardness: 2 - 3
Density: 2.7 - 3.4
Streak: Colourless
Lustre: Vitreous
Habit: Micaceous
Colours: Brown, black, reddish brown
   Crystal System: Monoclinic
Cleavage: Perfect basal
Fracture: Uneven
Magnetism: None
Reaction with HCl: Very weak
Identification in hand sample:
Colour and habit
Associations:
A very common mineral found in igneous, metamorphic and sedimentary rocks.
Industrial / ecomonic uses:
Altered into vermiculite, biotite is used as an insulation material and as filler in certain building supplies.



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