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

Stone sphere balls - full range in stock "Bertrandite"

Bertrandite is a rare mineral that forms small flattened or wedge-shaped prismatic crystals. It is also found in the form of continuous masses or radial-radiant splices. Often found in rare earth deposits Bertrandite is characterized by impurities of boron and germanium. Mined as an ore for beryllium. Named after the French mineralogist E. Bertrand.

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

Physical properties of Bertrandite

General
Category Sorosilicate
Formula
(repeating unit)
Be4Si2O7(OH)2
IMA symbol Btd
Strunz classification 9.BD.05
Crystal system Orthorhombic
Crystal class Pyramidal (mm2)
H-M symbol: (mm2)
Space group Ccm21
Unit cell a = 8.7135(4) Å,
b = 15.268(1) Å,
c = 4.5683(3) Å; Z = 4
Identification
Color Colorless to pale yellow
Crystal habit Thin tabular, prismatic to needle-like crystals commonly in radial clusters
Twinning Common on {011} or {021} forming heart or V shaped twins
Cleavage Perfect on {001}; distinct on {100}, {010} and {110}
Mohs scale hardness 6 - 7
Luster Vitreous, pearly on cleavage surfaces
Diaphaneity Transparent
Specific gravity 2.59 - 2.60
Optical properties Biaxial (-)
Refractive index nα = 1.591 nβ = 1.605 nγ = 1.614
Birefringence δ = 0.023
2V angle Measured: 73° to 81°
Code: 1425
Ermakovskoe deposit, Buryatia, RF
62mm

0.00 $ $216.36

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