ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001), Brittle, Metallic
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
BeAlSiO 4(OH)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
CaCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references