Onyx
Banded variety / From Wikipedia, the free encyclopedia
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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; agate has curved bands while onyx has parallel bands. The colors of its bands range from black to almost every color. Specimens of onyx commonly contain bands of black and/or white.[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 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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