Chalcedon
The site of Chalcedon is located on a small peninsula on the north coast of the Sea of Marmara, near the mouth of the Bosphorus. A stream, called the Chalcis or Chalcedon in antiquity and now known as the Kurbağalıdere (Turkish: "stream with frogs"), flows into Fenerbahçe bay. There Greek colonists from Megara in Attica founded the settlement of Chalcedon in 685 BC, some seventeen years before Byzantium.
Gemstones in the Bible
Chalcedony, Apoc., xxi, 19, "chalkedon"; Vulg. "chalcedonius", the third foundation stone of the celestial Jerusalem. The view that the writing "chalkedon" is an error and that it should be "charkedon" (the carbuncle) is not without some reason. However, the other eleven stones correspond to a stone in the rational and this is the only exception. The ancients very often confounded the names of these two stones. Chalcedony is a siliceous stone. Its name is supposed to derive from Chalcedon, in Bithynia, where the ancients obtained the stone from. It is a species of agate and bears various names according to its colour. Chalcedony is usually made up of concentric circles of various colours and the most valuable of these stones are found in the East Indies. The gem is used for rings, seals and, in the East; drinking vessels.