Uneven
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
(Fe2+ ,Mg)Al 2(PO 4) 2(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)
(K,Cs)Al 4Be 4(B,Be) 12O 28Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references