A form of chalcedony, onyx can be found with bands of white or brownish orange(called sardonyx) Plain black onyx is linked with the root chakra and is considered a stone of inner strength with a protective nature. it grounds us helping to calm our spirits in the face of troubles. It also helps stop the drain of persona energy around those who seem to 'suck the energy' right out of us. In this way it protects us against negative intereferenc.  Also know as a magical stone when used in scrying and the making of amulets for protection .