Onyx primarily refers to the parallel banded variety of the silicate mineral chalcedony. Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands: agate has curved bands and onyx has parallel bands. The colors of its bands range from black to almost every color. Commonly, specimens of onyx contain bands of black and/or white. Onyx, as a descriptive term, has also been applied to parallel banded varieties of alabaster, marble, obsidian, and opal, and misleadingly to materials with contorted banding, such as "Cave Onyx" and "Mexican Onyx".
Onyx comes through Latin (of the same spelling), from the Greek ὄνυξ, meaning "claw" or "fingernail". Onyx with flesh-colored and white bands can sometimes resemble a fingernail.
Onyx comes mainly in three colors (or color combinations): black, black and white, and grey and white. There are also other varieties, such as green or red onyx, but black is the most popular color of this stone.
Onyx is a gemstone found in various regions of the world including Yemen, Uruguay, Argentina, Australia, Brazil, Canada, China, Czech Republic, Germany, India, Indonesia, Madagascar, Latin America, the UK, and various states in the US.
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, notably from the archaeological recoveries at Knossos.
Brazilian green onyx was often used as plinths for art deco sculptures created in the 1920s and 1930s. The German sculptor Ferdinand Preiss used Brazilian green onyx for the base on the majority of his chryselephantine sculptures. Green onyx was also used for trays and pin dishes – produced mainly in Austria – often with small bronze animals or figures attached.
Onyx is mentioned in the Bible many times. Sardonyx (onyx in which white layers alternate with sard - a brownish color) is mentioned in the Bible as well.