BIOTITE


Meaning of BIOTITE in English

General Information:

Chemical Formula:

K(Mg,Fe++)3[AlSi3O10(OH,F)2

Composition:

(Molecular Weight = 433.53 gm)

Potassium 9.02 % K

Magnesium 14.02 % Mg

Aluminum 6.22 % Al

Iron 6.44 % Fe

Silicon 19.44 % Si

Hydrogen 0.41 % H

Oxygen 43.36 % O

Fluorine 1.10 % F

Empirical Formula:

KMg2.5Fe2+0.5AlSi3O10(OH)1.75F0.25

Environment:

Granitic rocks. Forms a series with phlogopite. Has several polytypes (1M, 3T, 2M1)

Locality:

Common world wide.

Name Origin:

Named after the French physicist, Jean Baptiste Biot (1774 - 1862), who studied the optical properties of the micas.

Physical Properties:

Cleavage:

[001] Perfect

Color:

dark brown, greenish brown, blackish brown, yellow, or white.

Density:

2.8 - 3.4, Average = 3.09

Diaphaniety:

Transparent to translucent to opaque

Habits:

Micaceous - Platy texture with "flexible" plates., Lamellar - Thin laminae producing a lamellar structure., Pseudo Hexagonal - Crystals show a hexagonal outline.

Hardness:

2.5-3 - Finger Nail-Calcite

Luminescence:

None.

Luster:

Vitreous - Pearly

Streak:

gray

More details...

Mineralogy database English vocab.      Английский словарь базы данных минералогии .