Onyx is a semi-precious variety of agate distinguished by parallel bands of black and white chalcedony, as opposed to the more chaotic banding of other agates. Black onyx is the most popular variety but is not as common as that with banding, such as sardonyx. Most carved and polished “onyx” is actually banded calcite from Mexico or Pakistan. From the Greek onux, meaning “nail,” this stone was widely used by ancient Greeks and Romans. Onyx is thought to increase regeneration, happiness, and intuition. Onyx is mined in Brazil, India, California and Uruguay.