ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
SiO 2Ulrich Henn and Claudio C.
BaCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references