Sillimanite and Erythrite Optical Properties

Sillimanite

Erythrite

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1 Optical Properties

1.1 Luster

Vitreous, Subadamantine, Silky

Subadamantine, Pearly

1.2 Pleochroism

Colourless to pale brown to yellow

Visible: X = pale pinkish to pale rose; Y = pale violet to pale violet-rose; Z = deep red

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

Transparent, Translucent

Not Available

1.5 Refractive Index

1.653-1.6851.626-1.629

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Orthorhombic

monoclinic

1.8 Birefringence

0.020-0.022Not Available

0 0.296

1.9 Clarity

Transparent

Not Available

Sillimanite and Erythrite Optic Character

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

Similar to their colors, Sillimanite and Erythrite 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.