This precious stone is known for the energy of strong support, stamina, and determination to help one's persevere. It is said to teach the wearer to rely on own powers; which is then often crafted as traditional wealth bracelets and amulets.
Black onyx crystals can be used for grounding, protection, and self-control, and as a shield against negative energy. It also enhances discipline, allowing more ease in following through on goals and completing tasks.
 Its spiritual meanings are related to emotional balance and strength during difficult times.
Black onyx is thought by some to have protective qualities, making it advantageous to carry when traveling. It is said to be useful in fighting basic fears and helping to move beyond bad relationships--as well as to heal old emotional wounds. Onyx gives strength. It promotes vigour, steadfastness and stamina. Imparts self-confidence, helping you to be at ease in your surroundings. Onyx banishes grief, enhances self-control and stimulates the power of wise decision-making. 
Black Onyx is a root chakra stone as it brings all that glorious grounding energy to keep you connected to the earth beneath your feet. The root chakra is one of the most important chakras there is as it invites excess energy to be released from the body.
Onyx is the official birthstone for those native to the zodiac signs Leo or Capricorn, and is said to help these individuals with becoming masters of their own destinies.
Since ancient times Onyx is believed to absorb negative energy. The more negativity it absorbs the darker the crystal gets. It is said that Cleopatra used to wear Black Onyx for its protective features. Sensing negative energy, the crystal would vibrate, alerting the queen of potential danger.