Uneven, Uneven, Gems, Sixth Edition (2006)
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Al 2O 3Michael OâDonoghue , Gems, Sixth Edition (2006)
KNa 2Li(Fe2+ ,Mn2+ ) 2Ti 2Si 8O 24Michael OâDonoghue , Gems, Sixth Edition (2006)