B I O T I T E
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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. |