Iolite and Petalite Optical Properties

Iolite

Petalite

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1 Optical Properties

1.1 Luster

Vitreous

Vitreous, Pearly

1.2 Pleochroism

Not Available

AbsentWalter Schumann

1.3 Dispersion

NA0.01

0.007 1

1.4 Transparency

Transparent, Translucent, Transparent to translucent

Gemmological Tables (2004) More from other references

1.5 Refractive Index

1.52-1.561.502-1.523

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Orthorhombic

monoclinic

1.8 Birefringence

Not Available0.012-0.016

0 0.296

1.9 Clarity

Transparent to translucent

TransparentUlrich Henn and Claudio C. Milisenda

Iolite and Petalite Optic Character

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

Similar to their colors, Iolite and Petalite 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, Iolite is Translucent, Transparent and Transparent to translucent while Iolite is Translucent, Transparent and Transparent to translucent in appearance.