Onyx (SiO2) is the striped, semiprecious variety of agate (a type of chalcedony; microcrystalline quartz) with white and black alternating bands. As with other chalcedonies, onyx forms from the deposition of silica at low temperatures from silica-rich waters percolating through cracks and fissures in other rocks. Onyx is popular for carved cameos and intaglios because its layers can be cut to show a color contrast. Natural onyx comes from India and South America.


Onyx derives its name from the Greek onux, meaning "nail" or "claw," in allusion to the mineral's color.


Metaphysically Known For: Inner strength, focused attention, willpower, self-mastery, discipline, reason.