A beautiful variation of agate - onyx. If the agates of the strip have a concentric or oval shape, then onyx they are straight. Depending on the impurities, these gems have a different color and, accordingly, its names. Actually onyx, which is called Arabic, has alternating white and black layers, carnelonix (or carnelian) - red and white, chalcedononix - gray and white, sardonyx - brown and white.

A beautiful variation of agate - onyx. If the agates of the strip have a concentric or oval shape, then onyx they are straight

Fig. 1. Onyx marble.

The name of this gem comes from the Greek word "onyx", meaning "nail". This name, most likely, mineral received from the fact, that the Greeks appreciated onyxes with thicknesses of layers no more than the thickness of the nail. There are synonyms - nogat, onychion or onychy. Nogat is an ancient Russian gem name, consonant with the literal translation of the Greek name. These synonyms are now obsolete and do not apply.

Onyx is known since ancient times. This mineral is repeatedly mentioned even in the Bible. For example, in the book "Exodus" we meet the words of the Lord addressed to Moses: "These are the offerings which you must receive from them: gold and silver, and copper, onyx stone...". Onyx served as a valuable material for jewelers. On a beautiful mineral, the master applied a pattern outline and cut out the gem. At first they were stones with a deep image. Gems were cut out on soft minerals, and with the development of skill - and on solid. The requirements of fashion led to the fact that first of all the beauty of the source material was appreciated. Gems were spread from aquamarine, amethyst, hyacinth, grenade, emerald, topaz, sapphire.

The appearance of onyxes as a starting material produced a revolution in glyptic - the art of carving on precious and semiprecious colored stones. Thanks to the two-color and multilayered, they raised it to a new stage of development. Began to create cameos - carved stones with a convex image. One of the tops of this art is the so-called cameo Gonzaga, carved on a three-layered onyx in the 3rd century BC. Gifted to the Emperor Alexander the First in 1811, it is kept in the State Hermitage. It depicts a pair portrait - the Egyptian king Ptolemy and his wife Arsinoea. When working on a cameo master, the colors of the stone are beautifully used. The bottom layer is dark brown. Against this background, the second, white layer underlines the tenderness of Arsinoe's face, neck and shoulder. The face of Ptolemy is also white, but as if weather-beaten in campaigns. The next dark brown layer is used to depict the hair, helmet and auspices of Ptolemy. Some of the other cameos stored in the Hermitage are also carved in sardonyx. These include "Adam and Eve", "Head of Athena", "Oedipus and the Sphinx" and others. Onyx proved to be the most versatile material for stones. This contributed to the texture of the stone - the correct alternation of colored strips.

Onyx served as a material for ancient healers. It was recommended for stopping bleeding and improving bone adhesion to reduce pain applied to inflamed sites and tumors. We also put it on the stomach to weaken the colic. It was also believed that wearing onyxes exacerbates hearing. They were also worn to protect them from lies and infidelity. It was believed that this stone gives man courage.

Sometimes onyx is confused with marble onyx. But they differ not only in appearance, but also in chemical composition: marble is a crystalline limestone, a banded variety marble, which has nothing to do with this onyx. In all the currently used stone classifications, onyx and marble onyx belong to different groups. Marble - an ornamental stone. In some varieties, translucent - translucent to a depth of 3 cm. The hardness differs from the present onyx - the marble has a hardness of 3-3,5.

In ancient times, onyx was used to make various products, inlays, mosaics. According to legend, the temple of Solomon in Jerusalem did not have windows, for it was built of marble onyx, which passed the daylight. One of the lamps found in the tomb of Tutankhamun is made of marble onyx, its handles are made in the form hieroglyphs and denote a union with eternity. When the fire was lit in it, the images of the king, the approximate, the garlands of flowers clearly showed on the walls. From the Central Asian marble onyx, the tomb of Ulugbek was made in the tomb of Timurids Gur-Emir in Samarkand.