Black onyx is a type of onyx gemstone that is a member of the chalcedony family of silicate stones. It is identified by its harsh texture and vertical lines, and it is made up of alternating-colored groups of fine-grained quartz. Its appearance is like a large, opaque jet-black gemstone with a dull shine and waxy feel. Even though pure black onyx does occur naturally, that's why it is rare. Thus, heating and polishing are the reason for the majority of black onyx gemstones that are accessible in this color. Different cultures have different origin stories for this black stone, but it also has a lengthy history and is said to have extraordinary therapeutic and spiritual powers.