Bertrandite and Cordierite Iolite Optical Properties

Bertrandite

Cordierite Iolite

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1 Optical Properties

1.1 Luster

Vitreous

1.2 Pleochroism

none.

Strong trichroism: colorless to yellowish

1.3 Dispersion

NA0.02

0.007 1

1.4 Transparency

TransparentAnthony et al, Handbook of mineralogy (2001)

Transparent

1.5 Refractive Index

1.583-1.6141.542-1.578

1 3.25

1.6 Optic Character

Not Available

Biaxial/+

1.7 Crystal System

Orthorhombic Pyramidal H-M Symbol (mm2) Space Group: Ccm21

Not Available

1.8 Birefringence

Not Available0.008-0.012

0 0.296

1.9 Clarity

TransparentAnthony et al

Transparent

Bertrandite and Cordierite Iolite Optic Character

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

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Bertrandite and Cordierite Iolite Transparency

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