Chalcedony is a mineral composed of tiny, microscopic crystals of quartz. It is a microcrystalline form of silica, meaning its crystals are too small to be visible without the use of a microscope. Chalcedony typically has a waxy or glassy luster, and comes in a wide range of colors. Chalcedony is found all over the world, and usually forms in volcanic rocks, geodes, and in sedimentary rocks.
The name Chalcedony comes from the Latin word “chalcedonius” which is derived from the Greek word “khalkedon”. Chalcedony was found at the ancient Greek city of Chalcedon, on the Bosporus straight in Asia Minor (which is now a district in Istanbul, Turkey). Chalcedony is one of the oldest known gemstones. Ancients carved Chalcedony into cylindrical seals in Mesopotamia as early as the 7th century BCE. Blue Chalcedony has been used in cameos, jewelry, sculptures and intaglio carvings throughout history.