Foitite and Alexandrite Optical Properties

Foitite

Alexandrite

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1 Optical Properties

1.1 Luster

Vitreous

1.2 Pleochroism

Strong: pale lavender dark blueAnthony et al

Not Available

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

TranslucentAnthony et al, Translucent

Transparent, Transparent to nearly opaque

1.5 Refractive Index

Not Available1.739-1.770

1 3.25

1.6 Optic Character

Not Available

Biaxial/+

1.7 Crystal System

Trigonal Ditrigonal Pyramidal H-M Symbol (3m) Space Group: R 3m

Orthorhombic

1.8 Birefringence

Not Available0.007-0.010

0 0.296

1.9 Clarity

TranslucentAnthony et al

Transparent

Foitite and Alexandrite Optic Character

Foitite and Alexandrite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Foitite and Alexandrite 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 Foitite and Alexandrite 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. Alexandrite has Biaxial/+ character.

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Foitite and Alexandrite Transparency

Similar to their colors, Foitite and Alexandrite 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, Foitite is Translucent and TranslucentAnthony et al while Foitite is Translucent and TranslucentAnthony et al in appearance.