Dravite and Sillimanite Optical Properties

Dravite

Sillimanite

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1 Optical Properties

1.1 Luster

Vitreous

Vitreous, Subadamantine, Silky

1.2 Pleochroism

Very strong: pale yellow colorless

Colourless to pale brown to yellow

1.3 Dispersion

0.02NA

0.007 1

1.4 Transparency

Transparent

Transparent, Translucent

1.5 Refractive Index

1.614-1.6661.653-1.685

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

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

Orthorhombic

1.8 Birefringence

0.014-0.0320.020-0.022

0 0.296

1.9 Clarity

Transparent

Dravite and Sillimanite Optic Character

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

Similar to their colors, Dravite and Sillimanite 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, Dravite is Transparent while Dravite is Transparent in appearance.