A subspecies of quartz, a mineral called also white agate, resembling milk diluted with water, and more or less clouded or opake, with veins, circles and spots. It is used in jewelry. xXA variety of agate, in which white and gray layers alternate.

A subspecies of quartz, a mineral called also white agate, resembling milk diluted with water, and more or less clouded or opake, with veins, circles and spots. It is used in jewelry. The varieties of chalcedony are common chalcedony, heliotrope, chrysoprase, plasma, onyx, sard and — sardonyx.