Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula K (Mg,Fe)3AlSi3O10(F,OH)2. It is primarily a solid-solution series between the iron - endmember annite, and the magnesium -endmember phlogopite; more aluminous end-members include siderophyllite and eastonite.

Biotite is a rock-forming mineral found in a wide range of crystalline igneous rocks such as granite, diorite, gabbro, peridotite, and pegmatite. It also forms under metamorphic conditions when argillaceous rocks are exposed to heat and pressure to form schist and gneiss.

Sep 2, 2023 · Biotite is the most common mica mineral and also known as black mica, a silicate mineral in the common mica group. Approximate chemical formula K (Mg, Fe). It can be found in massive crystal layers weighing several hundred pounds.

Biotite is now a group name for phlogopite, siderophyllite and eastonite. Common world wide. Link to MinDat.org Location Data. Named in 1847 after the French physicist, Jean Baptiste Biot (1774 - 1862), who studied the optical properties of the micas. Comments: Brown book of pseudohexagonal biotite crystals in matrix.

A common, widespread, rock-forming mineral, biotite is a significant mineral in granites, diorites, and igneous pegmatites. In pegmatites, biotite crystals can be very large. It also occurs in schists, gneisses, and hornfels that resulted from either regional or contact metamorphism.

Jan 16, 2020 · Biotite forms sheets of iron, silicon, magnesium, aluminum, and hydrogen weakly bonded by potassium ions. Stacks of sheets form what are called "books" because of their resemblance to pages. Iron is the key element in biotite, giving it a dark or black appearance, while most forms of mica are pale in color.

biotite, a silicate mineral in the common mica group. It is abundant in metamorphic rocks (both regional and contact), in pegmatites, and also in granites and other intrusive igneous rocks. For chemical formula and detailed physical properties, see mica (table).

Biotite, also known, as ‘black mica’ is a rock-forming femic phyllosilicate that occurs in several igneous and metamorphic rocks. The mineral was named in honor of the French scientist Jean-Baptiste Biot, who devoted his life to study the optical properties of the micas. Biotites are a group of trioctahedral phyllosilicates (sheet silicate).

Biotite is a common rock-forming mineral, and is especially noted in metamorphic rock s such as schist and gneiss. It is also found in igneous rock such as granite s and rhyolites. Biotite is also the primary mica in rare earth pegmatite s. - Manganese-rich variety of Biotite.

Biotite refers to a group of common rock-forming minerals forming a series between phlogopite and annite. The name is best used as a field name for dark micas for which the exact composition has not been determined. It is found in a variety of occurrences. It occurs in plutonic igneous rocks ranging from granites to gabbronorite to syenites.