Uneven, Uneven, Gems, Sixth Edition (2006)
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Al 2O 3Michael OâDonoghue , Gems, Sixth Edition (2006)
Mg 3B 7O 13ClMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references