Chal*ced"o*ny (kăl*s&ebreve;d"&osl;*n&ybreve; or kăl"s&esl;*d&osl;*n&ybreve;; 277), n.; pl. Chalcedonies (-n&ibreve;z). [ L. chalcedonius, fr. Gr. CHalkhdw`n Chalcedon, a town in Asia Minor, opposite to Byzantium: cf. calcédoine, OE. calcidoine, casidoyne. Cf. Cassidony.] (Min.) A cryptocrystalline, translucent variety of quartz, having usually a whitish color, and a luster nearly like wax. [Written also calcedony.]

&fist; When chalcedony is variegated with with spots or figures, or arranged in differently colored layers, it is called agate; and if by reason of the thickness, color, and arrangement of the layers it is suitable for being carved into cameos, it is called onyx. Chrysoprase is green chalcedony; carnelian, a flesh red, and sard, a brownish red variety.