The onix or onyx is a type of chalcedony of the family of quartz that can be found in black and white, or gray. . Also known as, marble onyx, with chemical representation SiO2, is composed of silicon or silicon oxide and reaches a hardness of 7 on the scale of mosh. Its formation is volcanic, caused by the accumulation of volcanic gases. It is used mainly for jewelry and decorative items, for the attractiveness of its greenish tones, and for the quality of its polish.
