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

Collectible minerals - full range in stock "Tourmaline"

Tourmaline is a group of boron-containing minerals of variable composition similar in composition. It has the following types and subspecies:

        Elbaite, Na(Al,Li)3Al6(BO3)3[Si6O18](O,OH,F)4, including
        Rubellite - pink to red
        Indicolite - sapphire blue
        Verdelite - green
        Achroite - colorless
          Dravite, NaMg3Al6(BO3)3[Si6O18](O,OH,F)4 , including Uvit CaMg3Al6
          Schorl, NaFe3Al6(BO3)3[Si6O18](O,OH,F)4

They have the property of hemimorphism - asymmetric faceting of the sides of different ends of the crystal. A well-faceted end becomes negatively charged when heated, while the other, less well-cut end is positively charged. Large crystals of tourmaline are used in radio engineering. Tourmalines are widely used in jewelry and in collecting.

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

Physical properties of Tourmaline

Category Cyclosilicate
(repeating unit)
(Ca,K,Na,▢)(Al,Fe,Li,Mg,Mn)3(Al,Cr, Fe,V)6(BO3)3(Si,Al,B)6O18(OH,F)4
IMA symbol Tur
Crystal system Trigonal
Crystal class Ditrigonal pyramidal (3m)
H-M symbol: (3m)
Space group R3m (no. 160)
Color Most commonly black, but can range from colorless to brown, red, orange, yellow, green, blue, violet, pink, or hues in between; can be bi-colored, or even tri-colored; rarely can be neon green or electric blue
Crystal habit Parallel and elongated. Acicular prisms, sometimes radiating. Massive. Scattered grains (in granite).
Cleavage Indistinct
Fracture Uneven, small conchoidal, brittle
Tenacity Brittle
Mohs scale hardness 7.0–7.5
Luster Vitreous, sometimes resinous
Streak White
Diaphaneity Translucent to opaque
Specific gravity 3.06+0.20−0.06
Density 2.82–3.32
Polish luster Vitreous
Optical properties Double refractive, uniaxial negative
Refractive index nω = 1.635–1.675
nε = 1.610–1.650
Birefringence −0.018 to −0.040; typically about −0.020 but in dark stones it may reach −0.040
  • Typically moderate to strong
  • Red: definite; dark red, light red
  • Green: strong; dark green, yellow-green
  • Brown: definite; dark brown, light brown
  • Blue: strong; dark blue, light blue
Dispersion 0.017
Ultraviolet fluorescence Pink stones; inert to very weak red to violet in long and short wave
Absorption spectra Strong narrow band at 498 nm, and almost complete absorption of red down to 640 nm in blue and green stones; red and pink stones show lines at 458 and 451 nm as well as a broad band in the green spectrum
Code: 153
Malkhan, stone vein "October", Transbaikalia, Eastern Siberia, RF

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Code: 150
Malkhan, stone vein "October", Transbaikalia, Eastern Siberia, RF

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Code: 1648
Malkhan, Buryatia, Eastern Siberia, RF

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Code: 964
Malkhan, Transbaikalia, Eastern Siberia, RF

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Code: 154
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Code: 152
Malkhan, stone vein "October", Transbaikalia, Eastern Siberia, RF

0.00 $ $96.67

Code: 2652
Malkhan, stone vein "October", Transbaikalia, Eastern Siberia, RF

0.00 $ $59.00

Code: 155
Malkhan, stone vein "October", Transbaikalia, Eastern Siberia, RF

0.00 $ $600.00

Code: 151
Malkhan, stone vein "October", Transbaikalia, Eastern Siberia, RF

0.00 $ $56.67

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