Amethyst information
	Chemistry: SiO2 , Silicon dioxide Class: Silicates Subclass: Tectosilicates Group: Quartz Uses: Silica for glass, electrical components, optical lenses, abrasives, gemstones, ornamental stone, building stone, etc. Luster: Glassy to vitreous as crystals, while cryptocrystalline forms are usually waxy to dull but can be vitreous. Transparency: Crystals are transparent to translucent, cryptocrystalline forms can be translucent or opaque. Crystal System: Trigonal; 3 2. Crystal Habits: Widely variable but the most common habit is hexagonal prisms terminated with a six sided pyramid (actually two rhombohedrons). Three of the six sides of the pyramid may dominate causing the pyramid to be or look three sided. Left and right handed crystals are possible and identifiable only if minor trigonal pyramidal faces are present. Druse forms (crystal lined rock with just the pyramids showing) are also common. Massive forms can be just about any type but common forms include botryoidal, globular, stalactitic, crusts of agate such as lining the interior of a geode and many many more. Cleavage: Very weak in three directions (rhombohedral). Fracture: Conchoidal. Hardness: 7, less in cryptocrystalline forms. Specific Gravity: 2.65 or less if cryptocrystalline. (average) Streak: White. Other Characteristics: Striations on prism faces run perpendicular to C axis, piezoelectric (see tourmaline) Index of refraction: 1.55.