Australia, Brazil, Canada, Colombia, Madagascar, Zimbabwe
Afghanistan, Pakistan, Burma, Brazil, Madagascar, USA, Canada, Russia, Madagascar, Brazil, Canada, Mexico, Madagascar, Brazil, Canada, Mexico
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Gemstones of the world (2001), UnevenWalter Schumann, Gemstones of the world (2001)