Splintery, Brittle, Uneven
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
NaCa 2(Mg 4Al)Si 6Al 2O 22(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)
KNa 2Li(Fe2+ ,Mn2+ ) 2Ti 2Si 8O 24Michael OâDonoghue , Gems, Sixth Edition (2006)