Afghanistan, Pakistan, Burma, Brazil, Madagascar, USA, Canada, Russia, Madagascar, Brazil, Canada, Mexico, Madagascar, Brazil, Canada, Mexico
Afghanistan, Brazil, Southern and central Africa, Madagascar, Russia, USA, Zimbabwe
Gemstones of the world (2001), UnevenWalter Schumann, Gemstones of the world (2001)
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)