Southern and central Africa
USA, Zambia, Madagascar, India, Sri Lanka, Russia, Australia, Color: violet, purple-violet, Hardness: 7, Refractive index: 1.54 1.55, Density: 2.65 2.66, Chemical composition: SiO2, Crystal structure: hexagonal, Lustre: vitreous, Origins: Widespread; main sources are Brazil, Uruguay, Bolivia, Argentina, East Africa, Namibia, Brazil
Brown
Violet, White, Colorless, Blue, Red, Green, Yellow, pink
torn surfaces, (e.g. fractured metals).
Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)