Norbergite and Sillimanite Optical Properties

Norbergite

Sillimanite

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1 Optical Properties

1.1 Luster

Vitreous

Vitreous, Subadamantine, Silky

1.2 Pleochroism

Pale yellow very pale yellow colorlessAnthony et al

Colourless to pale brown to yellow

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

Transparent

Transparent, Translucent

1.5 Refractive Index

1.563-1.5931.653-1.685

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Not Available

Orthorhombic

1.8 Birefringence

Not Available0.020-0.022

0 0.296

1.9 Clarity

Transparent

Norbergite and Sillimanite Optic Character

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

Similar to their colors, Norbergite 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, Norbergite is Transparent while Norbergite is Transparent in appearance.