Amethyst (Gr. preventing intoxication, so named because it was supposed by the ancient Persians that cups made of it would prevent the liquor they contained from intoxicating), a stone consisting of crystallized quartz of a purple or bluish violet color, probably derived from a very small amount of oxide of manganese or, according to Heintz, from a compound of iron and soda. The color is not always uniformly diffused through it, and is less brilliant by candlelight. The name was used by the ancients for several other minerals, which had a color similar to the amethyst. In mineralogy, amethyst is that variety of quartz that exhibits a wrinkled fracture, instead of the usual conchoidal one. - For oriental amethyst, see Sapphire.