Onyx is a type of chalcedony, which is a form of microcrystalline quartz. It is a parallel-banded variety of chalcedony, with straight, nearly parallel bands or layers of color. Onyxes can be black, white, or almost any color, and they feature multiple layers, with the lighter layer of stone sitting on top of the darker layer. Onyxes have been used for centuries to create intricate cameos and intaglios, as well as for solid black jewelry stones. Onyx is a relatively hard gemstone, with a hardness of 7, which means it can resist scratching from everyday wear. Onyxes can make durable jewelry stones, and they are often used in necklaces, bracelets, and other jewelry. Onyx is also believed to have healing and protective properties, and it is a root chakra stone that brings grounding energy.