Thulite and Sillimanite Optical Properties

Thulite

Sillimanite

Add ⊕

1 Optical Properties

1.1 Luster

Vitreous

Vitreous, Subadamantine, Silky

1.2 Pleochroism

Present

Colourless to pale brown to yellow

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

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

Transparent, Translucent

1.5 Refractive Index

1.6951.653-1.685

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Orthorhombic

1.8 Birefringence

0.006-0.0180.020-0.022

0 0.296

1.9 Clarity

OpaqueHerve Nicolas Lazzarelli

Transparent

Thulite and Sillimanite Optic Character

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

Compare Red Gemstones

Thulite Vs Tugtupite

Thulite Vs Uvite

Thulite Vs Verdite

Thulite and Sillimanite Transparency

Similar to their colors, Thulite 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, 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.