This mineral is named after the French physicist Biot, who lived from 1774 to 1862. It is a kind of mica, often called "black mica." Large sheets of biotite were once used as heat-resistant windows on ovens and furnaces.
dark brown to black mica found in igneous and metamorphic rock
A dark, iron and magnesium-rich mica found in granite.
K(Mg,Fe)(AlSi 10)(OH). The dark colored, iron- and magnesium-bearing member of the mica family.
The black variety of the mica group of minerals containing potassium, aluminum, magnesium and iron; it splits easily into thin, translucent sheets.
A platy magnesium-iron mica, common in igneous rocks.
A dark brown to green, magnesium-iron mica commonly found in igneous and metamorphic rocks.
Rock forming mineral of the mica group.
Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula K(Mg, Fe)3AlSi3O10(F, OH)2. More generally, it refers to the dark mica series, primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more aluminous endmembers include siderophyllite.