Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
KNa 2Li(Fe2+ ,Mn2+ ) 2Ti 2Si 8O 24Michael OâDonoghue , Gems, Sixth Edition (2006)
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.