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Bertrandite
Bertrandite

Dravite
Dravite



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Bertrandite
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Dravite

Bertrandite and Dravite Optical Properties

Optical Properties

Luster

Vitreous
Vitreous

Pleochroism

none.
Very strong: pale yellow colorless

Dispersion

0.010.02
0.005 1
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Transparency

TransparentAnthony et al
Transparent

Refractive Index

1.583-1.6141.614-1.666
1 3.25
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Optic Character

-
-

Crystal System

Orthorhombic Pyramidal H-M Symbol (mm2) Space Group: Ccm21
Trigonal Ditrigonal Pyramidal H-M Symbol (3m) Space Group: R 3m

Birefringence

-99990.014-0.032
0 0.296
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Clarity

TransparentAnthony et al
Transparent

Bertrandite and Dravite Optic Character

Bertrandite and Dravite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Bertrandite and Dravite Physical Properties like crystallographic symmetry, pleochroism,etc. in the crystal. Some of the optical properties are refractive index, luster, optic character, pleochroism etc. Prominent among these is Bertrandite and Dravite optic character. You might have noticed your gemologist rotating the gemstone while testing it. Rotating a gemstone along its optic axis helps in determining its optic character.

Bertrandite and Dravite Transparency

Similar to their colors, Bertrandite and Dravite transparency can also be used as criteria for their primary identification. Although transparency cannot be the only criteria for gemstone identification, it can efficiently used in gemstone grading. Talking about their transparency, Bertrandite is TransparentAnthony et al while Bertrandite is TransparentAnthony et al in appearance.