In a correct use, the onyx defines the white variety and the black variety of the agate.
Black Onyx: its tint is probably due to a natural irradiation.
To have more information on the mineralogy of the onyx, see Mindat.org->
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Onyx
- Translations : Onyx, Onice, Ónix, Onix, Onyks, Oniksas, Оникс, אוניקס, Onyksi, 缟玛瑙, أونيكس
- Etymology : From Greek "Onux" = scratch, nail
Gemological data
- Chemical formula : SiO2
- Hardness (Mohs) : 6.5 - 7
- Density : 2.6-2.65
- Refractive index : 1,53 - 1,543
- Crystal system : Trigonal
