The onyx is a variety of agate / of chalcedony. It ‘s a polycristallin quartz. The monochrome black Onyx is most of the time an agate coming from South America soaked with a solution concentrated by sugar then treated in the sulfuric acid then warmed.
Color: black to banded Black of White
Hardness: 6 - 7
Refractiveindex: 1,53 - 1,545
Density: 2.56 - 2.66. Even more (2,90).
Chemicalcomposition: SiO2 (dioxide of silicon)
Crystallinestructure: Trigonal / Microcrystallin
Luster: glassy, greasy, waxy
Origin: Germany, Austria, Italy, Brazil, Uruguay, the United States, etc.
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