SARDONYX
sardonyx
(noun) an onyx characterized by parallel layers of sard and a different colored mineral
Source: WordNet® 3.1
Etymology
Noun
sardonyx (countable and uncountable, plural sardonyxes)
A gemstone having bands of red sard; a variety of onyx or chalcedony.
(heraldry) A tincture of sanguine colour when the blazoning is done by precious stones.
Source: Wiktionary
Sar"do*nyx, n. Etym: [L., fr. Gr. Sard, and Onyx.] (Min.)
Definition: A variety of onyx consisting of sard and white chalcedony in
alternate layers.
Source: Webster’s Unabridged Dictionary 1913 Edition