1. The precious stone called onyx (a semi-pellucid gem with variously colored zones or veins, a variety of chalcedony or a subspecies of quartz, a mineral also called, "white agate".
2. Etymology: from Old French oniche, from Latin onyx, onychis; from Greek onyx, "onyx-stone"; originally "claw, fingernail".

So called because the mineral's color sometimes resembles that of a fingernail, pink with white streaks.