ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001), Brittle, Metallic
CaCO 3Ulrich Henn and Claudio C.
BeAlSiO 4(OH)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references