Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula K(Mg,Fe) 3 AlSi 3 O 10 (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 was regarded as a …

The name "biotite" is used in the field and in entry-level geology courses because these minerals generally cannot be distinguished without optical, chemical, or x-ray analysis.. 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 …

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.

Chrom-Biotit: A Cr-bearing variety of biotite. Chromium-bearing Biotite: A Cr-bearing variety of biotite. Eastonite (of Winchell) A variety of Biotite close to Eastonite. Heterophyllite: Designation for a uniaxial biotite from Mangualde, Portugal. Manganophyllite: A Mn-rich variety of biotite.

Biotite is found in abundance worldwide, but collectors specimens are not common and come from few localities. Noteworthy localities include Mabubas, Bengo Province, Angola; Mendig, Eifel Mts, Germany; and Serra da Freita, Arouca, Portugal, where it comes in rounded nodules. In Canada huge "books" and well formed "barrels" come from Bancroft, Hastings Co, Ontario and from Cardiff and ...

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 is …

Biotite and phlogopite are among the best naturally-occurring insulating materials. Both are widely used throughout industry but small differences in their composition lead to phologite’s widespread use in electrical systems while biotite is only used to insulate heating systems.

General Biotite Information : Chemical Formula: K(Mg,Fe++)3[AlSi3O10(OH,F)2 : Composition: Molecular Weight = 433.53 gm Potassium 9.02 % K 10.86 % K 2 O: Magnesium 14.02 % Mg 23.24 % MgO: Aluminum 6.22 % Al 11.76 % Al 2 O 3: Iron 6.44 % Fe 8.29 % FeO: Silicon 19.44 % Si 41.58 % SiO 2: Hydrogen 0.41 % H 3.64 % H 2 O: Oxygen 43.36 % O

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. Large crystals may form in pegmatites. It …

Relief: Moderate positive Habit/Form: Euhedral crystals are not uncommon, are usually tabular parallel to (001), and have a roughly hexagonal cross section. Also found as micaceous or tabular grains, or grains with irregular outline. Grains may be bent, particularly in metamorphic rocks.