Answer by
mammakat (11147)
Chalcedony is a durable stone requiring no special care or cleaning. They are a cryptocrystalline (made up of microfine crystals) form of silica quartz. Agate, adventurine, carnelian and onyx are well known species of Chalcedony. In history carnelian is particularly well known as a carved form of jewelry often used for signets, intaglio and cameo carvings.
