Onyx primarily refers to the parallel banded variety of chalcedony, a silicate mineral. Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands: agate has curved bands and onyx has parallel bands. The colors of its bands range from black to almost every color.
The onyx is a stone that offers its bearer immensely powerful vibrations of protection, willpower, focus and strength. Many believe that the onyx is there to drive motivation and to continuously push you forward in your life. It activates your root and solar plexus, as well as your third eye chakras.