AMETHYST, a violet or purple variety of quartz used as an ornamental stone. The name is generally said to be derived from the Gr. a, "not" and UE7varcErv, "to intoxicate," expressing the old belief that the stone protected its owner from strong drink. It was held that wine drunk out of a cup of amethyst would not in toxicate. The colour of amethyst is usually attributed to the pres ence of manganese, but as it is capable of being much altered and even discharged by heat it has been referred by some authorities to an organic source. On exposure to heat, amethyst generally be comes yellow, and much of the cairngorm or yellow quartz of jewellery is said to be merely "burnt amethyst." The amethyst was used as a gem-stone by the ancient Egyptians, and was largely employed in antiquity for intaglios. It is now used for episcopal rings. It is a very widely distributed mineral. but fine, clear specimens fit for cutting as ornamental stones are con fined to comparatively few localities. Such crystals occur either in cavities in mineral-veins and in granitic rocks, or as a lining in agate geodes. Many of the hollow agates of Brazil and Uruguay contain a crop of amethyst-crystals in the interior. Much fine ame thyst comes from Russia, especially from near Mursinka in the Ekaterinburg district.