Gemstones Tools

Onyx

Onyx marquise cabochon
(on'-iks')

12th c; gr. onux

Chalcedony with alternating black and white bands, used as a gemstone especially in making cameos and intaglios
Color
Opaque black with white bands
Family
Chalcedony - Cryptocristalline quartz
Chemical composition
SiO2
Crystal system
Hexagonal
Hardness (Mohs scale)
6,5 - 7
Specific gravity
2,60 ±0,05
Refractive index
1,537 ±0,02
Birefringence
Invisible
Optical character
None (aggregate)
Chanthaburi

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Jaipur

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