Fayalite and Sillimanite Optical Properties

Fayalite

Sillimanite

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1 Optical Properties

1.1 Luster

Vitreous, Resinous

Vitreous, Subadamantine, Silky

1.2 Pleochroism

Faint

Colourless to pale brown to yellow

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

TransparentAnthony et al, Handbook of mineralogy (2001)

Transparent, Translucent

1.5 Refractive Index

1.827-1.8791.653-1.685

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Orthorhombic

1.8 Birefringence

0.042-0.0510.020-0.022

0 0.296

1.9 Clarity

TransparentAnthony et al

Transparent

Fayalite and Sillimanite Optic Character

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

Similar to their colors, Fayalite 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, Fayalite is Handbook of mineralogy (2001) and TransparentAnthony et al while Fayalite is Handbook of mineralogy (2001) and TransparentAnthony et al in appearance.