1: χαλκηδών
(Strong's #5472 — Noun Masculine — chalkedon — khal-kay-dohn' )

the name of a gem, including several varities, one of which resembles a cornelian, is "supposed to denote a green silicate of copper found in the mines near Chalcedon" (Swete, on the Apocalypse), Revelation 21:19 .