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
Black
Violet, White, Colorless, Blue, Red, Green, Yellow, pink
ConchoidalArthur Thomas, Gemstones (2009)
Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)