Back Ónix AN جزع (حجر كريم) Arabic اونيكس ARZ Oniks Azerbaijani Онікс Byelorussian Онікс BE-X-OLD Оникс Bulgarian Ònix Catalan Onyx Czech Onyx Danish
| Onyx | |
|---|---|
 Onyx with concentric banding | |
| General | |
| Category | Tectosilicate minerals, quartz group, chalcedony variety, agate variety |
| Formula | SiO2 (silicon dioxide) |
| Crystal system | Trigonal (quartz), Monoclinic (moganite) |
| Identification | |
| Formula mass | 60.08 g/mol |
| Color | Black and white; red to brown with black or white (sardonyx) |
| Cleavage | None |
| Fracture | Uneven, conchoidal |
| Mohs scale hardness | 6.5–7 |
| Luster | Vitreous, silky |
| Streak | White |
| Diaphaneity | Translucent |
| Specific gravity | 2.55–2.70 |
| Optical properties | Uniaxial/+ |
| Refractive index | 1.530–1.543 |
| References | [1][2] |
Onyx is a typically black-and-white banded variety of agate, a silicate mineral. The bands can also be monochromatic with alternating light and dark bands. Sardonyx is a variety with red to brown bands alternated with black or white bands. The name "onyx" is also frequently used for level-banded (parallel-banded) agates, but in proper usage it refers to color pattern not band structure.[1] Onyx, as a descriptive term, has also been incorrectly applied to parallel-banded varieties of alabaster, marble, calcite, obsidian, and opal, and misleadingly to materials with contorted banding, such as "cave onyx" and "Mexican onyx".[1][3][4]
- ^ a b c "Onyx". Mindat.org. Retrieved 2025-02-14.
- ^ "Onyx". gemdat.org. Retrieved 2015-08-22.
- ^ Manutchehr-Danai, Mohsen (2013). Dictionary of Gems and Gemology. New York: Springer. pp. 340–341. ISBN 9783662042885.
- ^ Schumann, Walter (2009). Gemstones of the World. New York: Sterling. p. 158. ISBN 9781402768293.