Afghanistan, Pakistan, Burma, Brazil, Madagascar, USA, Canada, Russia, Madagascar, Brazil, Canada, Mexico, Madagascar, Brazil, Canada, Mexico
Brazil, Tanzania, Zimbabwe, Madagascar, Burma, Sri Lanka, India
Gemstones of the world (2001), UnevenWalter Schumann, Gemstones of the world (2001)
ConchoidalGemdat.org, Management Team (2012), ConchoidalGemdat.org, Management Team (2012)