Chalcedony is a fine grained variety of quartz. Its crystals are too small to be seen with the naked eye.
In ancient times chalcedony was used to make goblets lined with silver. It was believed they could offer protection against poisoning.
Blue chalcedony especially material used for gemstones is often dyed.
At the Palace of Knossos which is a Bronze Age site in Crete, chalcedony seals have been found which date to approximately 1800 BC.
Jasper, agate, carnelian, onyx, chrysoprase and bloodstone are all varieties of chalcedony.
CARNELIAN
