Black onyx is a chalcedony variety and a member of the quartz group. It is very rare in nature, but now there is a technology of its extractions from another stone - Zebra agate. Just after the extraction black onyx isn't very appealing. However, this does not confuse jewelers. They process it, and the mineral gets a beautiful shine. The stone is popular not only because of its look. The fact that black onyx has magical properties. Esotericists advise to wear it to those people who need a strong talisman.