Sillimanite and Proustite Optical Properties

Sillimanite

Proustite

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1 Optical Properties

1.1 Luster

Vitreous, Subadamantine, Silky

Adamantine

1.2 Pleochroism

Colourless to pale brown to yellow

Moderate; cochineal-red to blood-red

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

Transparent, Translucent

OpaqueUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) Rarely transparentMore from other references

1.5 Refractive Index

1.653-1.6852.792-3.087

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Orthorhombic

Trigonal

1.8 Birefringence

0.020-0.0220.295-0.296

0 0.296

1.9 Clarity

Transparent

OpaqueUlrich Henn and Claudio C. Milisenda

Sillimanite and Proustite Optic Character

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

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