onyx (n.)

type of quartz characterized by a structure in parallel bands differing in color or degree of translucency, used for cameos, etc., mid-13c., oneche; c. 1300, onix, from Old French oniche "onyx" (12c.), and directly from Latin onyx (genitive onychis), from Greek onyx "onyx-stone," originally "claw, talon, hoof, fingernail" (see nail (n.)). So called because the mineral's color sometimes resembles that of a human fingernail, pink with white streaks.