mineral
Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(OH,F)2)
AI-generated identification · may be incorrectHardness: 2.5-3.0 Mohs; Color: Dark brown, black, or dark green; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect basal cleavage (easily splits into thin sheets).
- Hardness
- 2
- Color
- Dark brown, black, or dark green
- Luster
- Vitreous to pearly
Identified More mineral →
Explore Biotite Mica in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 2.5-3.0 Mohs; Color: Dark brown, black, or dark green; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect basal cleavage (easily splits into thin sheets).
Formation & geological history
Formed in a wide range of igneous and metamorphic conditions. It is common in granites, schists, and gneisses. Geological age varies based on the host rock formation.
Uses & applications
Used in the electronics industry as an insulator, in paints as a filler, and by collectors for mineral specimens.
Geological facts
Biotite is known as 'black mica' and is part of a solid-solution series between phlogopite and annite. It was named in honor of Jean-Baptiste Biot, a French physicist.
Field identification & locations
Identify by its dark color and the way it flakes into flexible, elastic thin sheets. It is very common worldwide in regions with continental crust.
More like this
Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous