O"nyx (?), n. [L., fr. Gr. ? a claw,
finger nail, a veined gem. See Nail, and cf. Onycha.]
(Min.) Chalcedony in parallel layers of different shades
of color. It is used for making cameos, the figure being cut in one
layer with the next as a ground.
Onyx marble, a banded variety of marble or
calcium carbonate resembling onyx. It is obtained from
Mexico.