? Biotite – Definition and Explanations



Biotite – Monte Somma Italy (XX5 mm)

Rough formula K(Mg,Fe)3(OH,F)2(Want to3AlO10)
Massive (The term mass is used to define two quantities related to one another…) form 433.53 g/mol
Color (Color is the eye’s subjective perception of one or more wave frequencies…) Green (Green is the complementary color corresponding to light of wavelength…) dark, dark brown, black
Crystal class and space group prismatic; C2/m
crystal system (A crystal system is a classification of crystals based on their…) monoclinic
Bravais lattice (In crystallography, a Bravais lattice is a regular distribution of points…) Centralized C
Macle on {001}
Division (Flexibility is the ability of certain minerals to break along flat surfaces…) parfaits {001}, thin, flexible and flexible cutting blades
habit tabular or prismatic crystals
with hexagonal or lozenge outlines
Broken (The term fracture in traumatology, by definition, determines the resolution of …) Unknown
Mohs scale (The Mohs hardness scale was invented by the German mineralogist Friedrich Mohs in 1812…) 2.5 – 3
Shine submetallic, vitreous, pearly
Optical properties
Refractive index (Measures the refractive index… factor of the medium at a given wavelength) α=1.565-1.625, β=1.605-1.675, γ=1.605-1.675
A break (A fracture is a physical property of a material that…) Δ=0.04-0.05; negative biaxial
Dispersion (In wave mechanics, dispersion is a phenomenon that affects the wave…) 2 vZ ~ 16-20
Fluorescence (Fluorescence is the emission of light caused by the excitation of a molecule…) ultraviolet (Ultraviolet (UV) radiation is electromagnetic radiation whose wavelength is…) None
Feature White (White is the color of a body heated to about 5000°C (see…)
Other features
Density (The density or relative density of a body is equal to the ratio of its density ….) 2.8 – 3.4
Solubility it melts with difficulty in giving glass (Glass, in everyday language, means a hard, brittle material or alloy…) magnetic black
Solvency It dissolves in H2There is no4
Different characters
Magnetism (Magnetism is a physical phenomenon through which forces are manifested…) None
Radioactivity (Radioactivity, a phenomenon discovered by Henri Becquerel in 1896…) slight
Main types

The biotite It is a mineral from the phyllosilicates subgroup of the mica family, from the silicates group. forms a series with phlogopite (Phlogopite is a mineral type and … subgroup of the silicate group). The ideal formula is K(Mg,Fe)3(OH, F)2(Want to3AlO10) with some tracks (TRACES (Trade Control and Expert System) is a veterinary health network…) of: Mn;Ti;Li;Ba;Na;Sr;Cs;Fe;Cl.

He has not been recognized since 1998-99 species (Species in life sciences (from Latin species, “type”…) In its own right by the International Association mineralogy (Mineralogy is the study of minerals.). The term biotite may appear as a synonym for phlogopite, including siderophyllitisI’annette (Fluorannite, Tetra-ferri-annite) andEstonian. This term is generally used to designate dark to black micas.

Inventor and etymology

Described in 1847 by Johann Friedrich Ludwig Hausmann. This is where the name biotite comes from. Jean-Baptiste Biot (Jean-Baptiste Biot (Paris, April 21, 1774 – Paris, 5…), physicist (A physicist is a scientist who studies the field of physics, ie…) A Frenchman who studied the optical properties of the mica family.


Biotite yields several polytypes number (The concept of number in linguistics is considered in the article “Number…”) layers variable (Represented in mathematics and logic by the variable symbol. This…). The symmetry (In general, the term symmetry refers to the presence, a…) depends on stacking of layers in each polytype. Polytypes are:

  • 2M (monoclinic) is the most common
  • 1M (monoclinic)
  • 3T (triangle)


Monte Somma, Somma-Vesuvius volcanic complex, Naples, Campania Italy.


  • lepidomelan (la) (Soltmann) generic term for rich black mica iron (Iron is a chemical element with symbol Fe and atomic number 26. It…)Illustrated at Presberg in Vermeland.
  • meroxen (the) (Johann August Friedrich Breithaupt); Described from very bright dark green Monte Somma crystals
  • odenite
  • oderite (Berzelius)


It is one of the main components of granites, gneisses and micaschists. Its alteration makes it chlorite. Biotite is one of the minerals that make up plutonic rocks (granites, diorites, syenites, especially in intermediate calc-alkaline families), metamorphic rocks (schists, gneisses and micaschists) and more rarely in volcanic rocks ().rhyolitesdacites, trachytes, andesites).


Biotite hydrates vermiculite or chlorite, often with Ti remaining in the form of microcrystals. rutile (Rutil is a type of titanium dioxide mineral with the formula TiO2…).

Related minerals

amphiboles, andalusite, cordierite, potassium feldspars, garnets, nepheline, Muscovite (Muscovite is a mineral type of the silicate subgroup…)plagioclase, pyroxenes, quartz, spinels.

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