Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001)
KNa 2Li(Fe2+ ,Mn2+ ) 2Ti 2Si 8O 24Michael OâDonoghue , Gems, Sixth Edition (2006)
Mg 2Al 4Si 5O 18Ulrich Henn and Claudio C.