A History of Chalcedony

Chalcedony (kal-SED-uh-nee)

Named after the ancient seaport of Chalcedon, now Kadikoy, Turkey, has a long history in jewelry. Greek seafarers in the third or fourth century AD wore chalcedony and carbuncle amulets to avoid drowning. In the eighteenth century, chalcedony was to night-time apparitions what garlic was to vampires. People believed someone seeing the nocturnal phantoms took in disease or evil humors through their eyes, but the “alkaline” content of chalcedony removed them.

In mineralogical terms, chalcedony is a microcrystalline aggregate of quartz. Quartz is the most abundant mineral in the Earth’s crust, so every country has many kinds of chalcedony. However, gemologically, it is treated as a sub-species because it’s properties differ from single-crystal quartz. Here is just a small handful of some of the different varieties of chalcedony:

Agate

Chrysoprase

Jasper

Onyx