Irregular/uneven, UnevenAnthony et al, Handbook of mineralogy (2001), Brittle, Uneven
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
CaAl 2Si 3O 10 · 3H 2OUlrich Henn and Claudio C.
MgAlBO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references