Chalced'onyx (or, erroneously, Calcedonyx), a name given to agates formed of eacholong, or a white opaque chalcedony, alternating with a grayish translucent chalcedony.
Chalced'onyx
Chambers's Encyclopaedia, Volume 3: Catarrh to Dion, p. 84
Source scan(s): p. 0093