Opal and Agrellite Optical Properties

Opal

Agrellite

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Optical Properties

Luster

Vitreous, Pearly

Pearly

Pleochroism

None

colorless.

Dispersion

0.010.01

0.005 1

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Transparency

Transparent, Translucent, Transparent to translucent

Refractive Index

1.37-1.521.567

1 3.25

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Optic Character

Crystal System

Trigonal

Triclinic

Birefringence

-99990.014

0 0.296

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Clarity

Transparent

Opal and Agrellite Optic Character

Opal and Agrellite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Opal and Agrellite 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 Opal and Agrellite 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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Opal Vs Simpsonite

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Opal and Agrellite Transparency

Similar to their colors, Opal and Agrellite 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, Opal is Transparent, Translucent and Transparent to translucent while Opal is Transparent, Translucent and Transparent to translucent in appearance.