Mentioned only in Revelation 21:19 , as one of the precious stones in the foundation of the New Jerusalem. The name of this stone is derived from Chalcedon, where it is said to have been first discovered. In modern mineralogy this is the name of an agate-like quartz of a bluish colour. Pliny so names the Indian ruby. The mineral intended in Revelation is probably the Hebrew nophekh , translated "emerald" ( Exodus 28:18 ; 39:11 ; Ezekiel 27:16 ; 28:13 ). It is rendered "anthrax" in the LXX., and "carbunculus" in the Vulgate. (See CARBUNCLE .)

These dictionary topics are from
M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition,
published by Thomas Nelson, 1897. Public Domain, copy freely.