from
The Collaborative International Dictionary of English v.0.48
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]