Opal and Covellite Optical Properties

Opal

Covellite

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1 Optical Properties

1.1 Luster

Vitreous, Pearly

Resinous

1.2 Pleochroism

None

Marked

1.3 Dispersion

NoneNA

0.007 1

1.4 Transparency

Transparent, Translucent, Transparent to translucent

OpaqueAnthony et al, Handbook of mineralogy (2001) More from other references

1.5 Refractive Index

1.37-1.521.45-2.62

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Trigonal

Hexagonal

1.8 Birefringence

Not AvailableNot Available

0 0.296

1.9 Clarity

Transparent

OpaqueAnthony et al

Opal and Covellite Optic Character

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

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