Onyx is a cryptocrystalline form of quartz. The colors of its bands range from white to almost every color (save some shades, such as purple or blue). It has a long history of use for hardstone carving and jewellery. The name has sometimes been used, incorrectly, to label other banded lapidary materials. This other material is much softer than true onyx. The majority of carved items sold as 'onyx' today are this carbonate material.