Thulite and Dravite Optical Properties

Thulite

Dravite

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1 Optical Properties

1.1 Luster

Vitreous

1.2 Pleochroism

Present

Very strong: pale yellow colorless

1.3 Dispersion

NA0.02

0.007 1

1.4 Transparency

Opaque, Translucent, Opaque . May be translucent in thin backlit sections.

Transparent

1.5 Refractive Index

1.6951.614-1.666

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Orthorhombic

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

1.8 Birefringence

0.006-0.0180.014-0.032

0 0.296

1.9 Clarity

OpaqueHerve Nicolas Lazzarelli

Transparent

Thulite and Dravite Optic Character

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

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Thulite and Dravite Transparency

Similar to their colors, Thulite 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, Thulite is Opaque, Opaque . May be translucent in thin backlit sections. and Translucent while Thulite is Opaque, Opaque . May be translucent in thin backlit sections. and Translucent in appearance.