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Diameter, mm (1mm - 0,039inch)

Collectible minerals - full range in stock "Biotite"

Biotite is a widespread mineral (up to 3% of the earth's crust), potassium-aluminum-magnesium-iron-containing variety of mica.

You can see biotite stone for sale and buy it in the Minerals of Russia online store.

Physical properties of Biotite

Category Phyllosilicate
(repeating unit)
IMA symbol Bt
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group C2/m
Color Dark brown, greenish-brown, blackish-brown, yellow
Crystal habit Massive to platy
Twinning Common on the [310],
less common on the {001}
Cleavage Perfect on the {001}
Fracture Micaceous
Tenacity Brittle to flexible, elastic
Mohs scale hardness 2.5–3.0
Luster Vitreous to pearly
Streak White
Diaphaneity Transparent to translucent to opaque
Specific gravity 2.7–3.3
Optical properties Biaxial (-)
Refractive index nα = 1.565–1.625
nβ = 1.605–1.675
nγ = 1.605–1.675
Birefringence δ = 0.03–0.07
Pleochroism Strong
Dispersion r < v (Fe rich);
r > v weak (Mg rich)
Ultraviolet fluorescence None
Major varieties
Manganophyllite K(Fe,Mg,Mn)3AlSi3O10(OH)2
Code: 2103
Afrikanda, Kola Peninsula, RF

0.00 $ $5.00

Code: 2684
Afrikanda, Kola Peninsula, RF

0.00 $ $21.67

Code: 3264
Afrikanda, Kola Peninsula, RF

0.00 $ $4.33

Code: 2519
Afrikanda, Kola Peninsula, RF

0.00 $ $4.33

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