Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Gems, Sixth Edition (2006), Gems, Sixth Edition (2006)
BaTiSi 3O 9Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
SiO 2Michael OâDonoghue , Gems, Sixth Edition (2006)