Onyx
Banded variety of mineral / From Wikipedia, the free encyclopedia
This article is about the mineral. For the New York hip hop group, see Onyx (hip hop group). For other uses, see Onyx (disambiguation).
Onyx is the parallel-banded variety of chalcedony, a silicate mineral. Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands. Onyx has parallel bands, while agate has curved bands. The colors of its bands range from black to almost every color. Specimens of onyx commonly contain bands of black or white or both.[1] Onyx, as a descriptive term, has also been 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]
Quick Facts General, Category ...
Onyx | |
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General | |
Category | Chalcedony variety (silicate minerals) |
Formula (repeating unit) | SiO2 (silicon dioxide) |
Crystal system | Trigonal |
Identification | |
Formula mass | 60.08 g/mol |
Color | Various |
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] |
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