Sardonyx
(Rev. 21:20), a species of the carnelian combining the sard and
the onyx, having three layers of opaque spots or stripes on a
transparent red basis. Like the sardine, it is a variety of the
chalcedony.
Bibliography Information Easton, Matthew George. M.A., D.D., "Definition for 'Sardonyx' Eastons Bible Dictionary". bible-history.com - Eastons; 1897.