Dravite and Holmquistite Optical Properties

Dravite

Holmquistite

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1 Optical Properties

1.1 Luster

Vitreous

1.2 Pleochroism

Very strong: pale yellow colorless

Strong in shades of violet when dark-colored.Anthony et al

1.3 Dispersion

0.02NA

0.007 1

1.4 Transparency

Transparent

1.5 Refractive Index

1.614-1.6661.622-1.666

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

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

Orthorhombic Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: P nma

1.8 Birefringence

0.014-0.032Not Available

0 0.296

1.9 Clarity

Transparent

Dravite and Holmquistite Optic Character

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

Similar to their colors, Dravite and Holmquistite 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, Dravite is Transparent while Dravite is Transparent in appearance.