Splintery, UnevenArthur Thomas, Difficult, Fibrous
Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Conchoidal
NaAlSi 2O 6Ulrich Henn and Claudio C.
PbCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references