onyx

Chalcedony Chal*ced"o*ny (k[a^]l*s[e^]d"[-o]*n[y^] or k[a^]l"s[-e]*d[-o]*n[y^]; 277), n.; pl. {Chalcedonies} (-n[i^]z). [ L. chalcedonius, fr. Gr. CHalkhdw`n Chalcedon, a town in Asia Minor, opposite to Byzantium: cf. calc['e]doine, 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}.] [1913 Webster]

Note: 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. [1913 Webster] ||