Onyx is associated primarily with the root chakra. It assists with challenges in life, especially those caused by a drain of energy. It prevents the draining away of personal energy and can be used for protection from such. It also helps with grounding and controlling or eliminating excess or unwanted energies.
It has been used for wound healing, childbirth and to increase stamina and self-control.
Black onyx and red onyx are associated with the base (root, first) chakra.
White onyx is associated with linking the base and crown chakras to have balanced energy throughout the chakra system.