Onyx marble is a semi-transparent mineral that is composed mainly of calcium carbonate. It forms in deposits of hot springs. Onyx has a dense grained structure. It is characterized by an irregular striped pattern with inclusions of other elements. For example, iron oxides give the stone its reddish and brown color; dark-green stripes appear in places rich in magnesium; and light green ones are caused by copper. The pure mineral without impurities is white.

The pastel-colored onyx marbles (light pink, yellow and green) are mostly imported from Azerbaijan. The stones with a rich brown hue may be found in the deposits of Turkmenistan. However, the most common type of the mineral has alternating stripes of different shades of golden-yellow and honey-brown. Onyxes of this color are mined in Armenia, Krasnodar and Krasnoyarsk Krai. The width of the stripes can vary from one millimeter to several centimeters. Sometimes, monochrome or spotty variants can be found, as well as stones with veins.

Onyx marble is used for manufacturing jewelry and decorative interior items: jewelry boxes, candlesticks, table clocks, and statuettes. The mineral is also widely used in interior decoration. It can be used for decorative panels, wall finishing, floors, and columns. It can be mounted in two ways: to a base with a neutral adhesive that will not change the natural color of the stone, or to a gap between the wall and the tiles. In the latter case, a light source is placed behind the stone panel: the rays pass through the semi-transparent onyx, and so the decor element starts to look like a stained-glass panel. There is also furniture inlaid with onyx.

Onyx marble weakly absorbs water, so it can be used to tile bathrooms, swimming pools, and banyas (saunas). This material can be used for the exterior decoration of buildings due to its frost resistance. Several Moscow metro stations, such as Belorusskaya, Kievskaya, and Dynamo, have decorative elements made out of pink and cream onyx, which was mined in Armenia.