Tourmaline and Bertrandite Optical Properties

Tourmaline

Bertrandite

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1 Optical Properties

1.1 Luster

Vitreous

1.2 Pleochroism

typically moderate to strong

none.

1.3 Dispersion

0.02NA

0.007 1

1.4 Transparency

Transparent, Translucent, Transparent to opaque

TransparentAnthony et al, Handbook of mineralogy (2001)

1.5 Refractive Index

1.614-1.6661.583-1.614

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Trigonal

Orthorhombic Pyramidal H-M Symbol (mm2) Space Group: Ccm21

1.8 Birefringence

0.014-0.040Not Available

0 0.296

1.9 Clarity

Transparent

TransparentAnthony et al

Tourmaline and Bertrandite Optic Character

Tourmaline and Bertrandite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Tourmaline and Bertrandite 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 Tourmaline and Bertrandite 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.

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Tourmaline and Bertrandite Transparency

Similar to their colors, Tourmaline and Bertrandite 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, Tourmaline is Translucent, Transparent and Transparent to opaque while Tourmaline is Translucent, Transparent and Transparent to opaque in appearance.