Sardonyx is a blend of sard and onyx. It is a variety of the microcrystalline quartz, chalcedony. Sardonyx has the straight white bands of onyx and the brownish red of sard.
The sardonyx stone is carved as small a sculpture and intaglio, or may be polished, tumbled, or cut as beads. The rough of the stone display straight bands at one position and is unbanded in other areas.
Occurrence
Sardonyx is found in many countries around the world. It is formed by deposition of silica in gas cavities in lava. That gives the stone is characteristic band.
Sardonyx Properties
- Specific Gravity: 2.61
- Refractive Index: 1.53-1.54
- Birefringence (DR): 0.004
- Luster: Vitreous
- Crystal Structure: Trigonal
- Composition: Silicon dioxide
- Hardness: 7
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