The first-century naturalist Pliny the Elder described both type of onyx and various artificial treatment techniques in his Naturalis Historia. Onyx was known to the Ancient Greeks and Romans. Sardonyx (onyx in which white layers alternate with sard - a brownish color) is mentioned in the Bible as well. Onyx is mentioned in the Bible many times. Green onyx was also used for trays and pin dishes – produced mainly in Austria – often with small bronze animals or figures attached. The German sculptor Ferdinand Preiss used Brazilian green onyx for the base on the majority of his chryselephantine sculptures. īrazilian green onyx was often used as plinths for art deco sculptures created in the 1920s and 1930s. Use of sardonyx appears in the art of Minoan Crete, notably from the archaeological recoveries at Knossos. Onyx was used in Egypt as early as the Second Dynasty to make bowls and other pottery items. Some onyx is natural but much of the material in commerce is produced by the staining of agate. It has also been used for intaglio and hardstone cameo engraved gems, where the bands make the image contrast with the ground. It has a long history of use for hardstone carving and jewelry, where it is usually cut as a cabochon or into beads. Historical use The Gemma Augustea is a Roman cameo produced 9–12 AD and carved in a two-layered onyx gem (19 × 23 cm) Onyx is a gemstone found in various regions of the world including Greece, Yemen, Uruguay, Argentina, Australia, Brazil, Canada, China, Czech Republic, Germany, Pakistan, India, Indonesia, Madagascar, Latin America, the UK, and various states in the US. In addition to dye treatments, heating and treatment with nitric acid have been used to lighten or eliminate undesirable colours. These techniques are still used, as well as other dyeing treatments, and most so-called "black onyx" sold is artificially treated. Treatments for producing black and other colours include soaking or boiling chalcedony in sugar solutions, then treating with sulfuric or hydrochloric acid to carbonise sugars which had been absorbed into the top layers of the stone. The first-century naturalist Pliny the Elder described these techniques being used in Roman times. Īrtificial onyx types have also been produced from common chalcedony and plain agates. The majority of carved items sold as "onyx" today are this carbonate material. This material is much softer than true onyx, and much more readily available. The name has also commonly been used to label other banded materials, such as banded calcite found in Mexico, India, and other places, and often carved, polished and sold. Most "black onyx" on the market is artificially colored. Artificial treatments have been used since ancient times to produce both the black color in "black onyx" and the reds and yellows in sardonyx. Black onyx is perhaps the most famous variety, but is not as common as onyx with colored bands. Sardonyx is a variant in which the colored bands are sard (shades of red) rather than black.
Its bands are parallel to one another, as opposed to the more chaotic banding that often occurs in agates. It is cryptocrystalline, consisting of fine intergrowths of the silica minerals quartz and moganite. Onyx is formed of bands of chalcedony in alternating colors. Varieties Red onyx (also called "Sardonyx") Black onyx with bands of colors The English word "nail" is cognate with the Greek word. Onyx with flesh-colored and white bands can sometimes resemble a fingernail.
Onyx comes through Latin (of the same spelling), from the Ancient Greek ὄνυξ, meaning "claw" or "fingernail". 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". Specimens of onyx commonly contain bands of black and/or white.
The colors of its bands range from black to almost every color. 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. Onyx primarily refers to the parallel-banded variety of chalcedony, an oxide mineral. For other uses, see Onyx (disambiguation). For the New York hip hop group, see Onyx (hip hop group).
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