Sillimanite and Antigorite Optical Properties

Sillimanite

Antigorite

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Optical Properties

Luster

Vitreous, Subadamantine, Silky

Waxy, Silky, Resinous, Greasy

Pleochroism

Colourless to pale brown to yellow

pale greenish yellow

Dispersion

0.020.02

0.005 1

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Transparency

Transparent, Translucent

Translucent

Refractive Index

1.653-1.6851.530-1.575

1 3.25

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Optic Character

Crystal System

Orthorhombic

Monoclinic Domatic H-M Symbol (m) Space Group: Cm

Birefringence

0.020-0.022-9999

0 0.296

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Clarity

Transparent

Translucent

Sillimanite and Antigorite Optic Character

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

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