8 letters · 19 points in Scrabble
noun an onyx characterized by parallel layers of sard and a different colored mineral
originInherited from Middle English sardonix, sardonyx (c. 1382), from Latin sardonyx, from Ancient Greek σᾰρδόνῠξ (sărdónŭx). Doublet of sardoin.
Etymology from Wiktionary, CC BY-SA 3.0