Onyx is a variety of mineral oxide calsedon. Agate and onyx are both layered varieties of kalsedon which differ only in ribbon form: agate has a curved ribbon and onyx has a parallel band. The band's colors range from white to almost every color (saving some shades, like purple or blue). Typically, onyx specimens contain black and/or white bands.
Video Onyx
Etymology
Onyx comes through the Latin (the same spelling), from the Greek ????, meaning "claw" or "fingernail". With the color fleshtone, onyx can be said to resemble a fingernail. The word "nail" in English is the same as the Greek word.
Maps Onyx
Variety
Onyx is formed from a collection of calconeons in alternating colors. It is a cryptocrystalline, composed of fine intergrowths of silica quartz minerals and moganite. The ribbons are parallel to one another, as opposed to the more chaotic bands that often occur on agate stones.
Sardonyx is a variant in which the colored band is sard (red) and not black. Black onyx is probably the most famous varieties, but it is not as common as onyx with colored bands. Artificial care has been used since ancient times to produce black in black onyx and red and yellow in sardonyx. Most "black onyx" on the market has an artificial color.
Imitation and care
This name is also commonly used to label other ribbon materials, such as calcite found in Mexico, India and elsewhere, and often carved, polished and sold. This material is much softer than the true onyx, and much more readily available. Most of the carved items sold as "onyx" today are these carbonate materials.
Artificial onyx types have also been produced from regular calcedon and agate. The first-century naturalist Pliny the Elder describes these techniques used in Roman times. Treatments to produce black and other colors include soaking or boiling calcinedone in a sugar solution, then treating with sulfuric acid or hydrochloric acid to hydrate the sugar that has been absorbed into the top layer of the stone. These techniques are still used, as well as other dye treatments, and so-called "black onyx" are sold artificially. In addition to dye treatment, heating and treatment with nitric acid have been used to relieve or eliminate unwanted colors.
Geographic events
Onyx is a gemstone found in various regions of the world including Yemen, Uruguay, Argentina, Australia, Brazil, Canada, China, Czech Republic, Germany, India, Indonesia, Pakistan, Madagascar, Latin America, UK, and various states in OUR.
Historical usage
It has a long history of use for chisel and hardstone jewelry, where it is usually cut as cabochon or beads. It has also been used for intaglio and hardstone cameo engraved gems, where bands make contrast with the ground. Some natural onyx but most of the material in trade is produced by agate staining.
Onyx was used in Egypt as early as the Second Dynasty to make bowls and other pottery items. The use of sardonyx appears in the art of Minoan Crete, especially from archaeological recovery at Knossos.
Brazilian green onyx is often used as a base for art deco statues made in the 1920s and 1930s. The German sculptor, Ferdinand Preiss, uses a Brazilian green onyx to base on most of his chrysellephantine statues. Onyx greens are also used for trays and pin plates - produced mainly in Austria - often with small bronze animals or numbers attached.
Onyx is mentioned in the Bible many times. Sardonyx (onyx in which the white layer alternates with sard) is mentioned in the Bible as well.
Onyx is known by Ancient Greeks and Romans. The first-century naturalist Pliny the Elder described both types of onyx and various artificial treatments in his book Naturalis Historia .
The onyx sheets (from the Atlas Mountains) are famously used by Mies van der Rohe at Villa Tugendhat in Brno (completed 1930) to create a shimmering semi-transparent interior wall.
The HÃÆ'Â'tel de la PaÃÆ'¯va in Paris is noted for its yellow onyx décor, and the Second Stage of the Mariinsky Theater in St.Petersburg uses yellow onyx in the lobby.
Superstition
The ancient Romans entered the battle carrying a sardonyx talisman carved with Mars, the god of war. This is believed to give courage in battle. In renaissance Europe, wearing sardonyx is believed to give eloquence. The traditional Persian belief is that it helps with epilepsy. Sardonyx is traditionally used by English midwives to facilitate labor by placing it between breasts of the mother.
See also
- Mineral list
References
Source of the article : Wikipedia
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