Amethyst
Amethyst is a violet variety of QUARTZ, and has a chemical composition of SiO2. Gem quality amethyst is a relatively inexpensive gemstone often used in jewelry. Amethyst mineral specimens, geodes and large cathedrals are prized by collectors. Amethyst occurs in a wide range of purple shades from pale lilac to deep purple. When amethyst is heated, it becomes CITRINE, a yellow or orange variety of quartz.
Chemistry: SiO2 ♦ Variety: Quartz ♦ transparent to translucent ♦ Luster: vitreous ♦ Crystal system: trigonal ♦ Moh's hardness: 7 ♦ Color: Various shades of purple ♦ Localities: may be found throughout the world, with notable western hemisphere occurrences in Brazil, Uruguay, Ontario, Vera Cruz, Mexico, Guerrero, Mexico, Maine, North Carolina, Pennsylvania, Colorado..