ConchoidalMichael OâDonoghue, Gems, Sixth Edition (2006), Gems, Sixth Edition (2006)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
SiO2
(Ca,Mn2+ )Si 3O 9Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references