Amethyst (ancient Greek. Αμέθυστος, from α- «no» + μέθυστος «to be drunk") - blue, bluish-pink or red-purple variety of quartz. It occurs usually in the form of freely seated in cavities and veins among crystalline rock crystals and their aggregates. The crystals are formed by the combination of planes of the prism and the rhombohedron, with all of it for quartz amethyst characteristic feature is the predominance of the faces of the rhombohedron. Less crystals have dlinnoprizmatichesky or skipetrovidno