Brittle, Uneven, Brittle, Uneven
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
NaCa16Si23AlO60(OH)8•64(H2O)
PbSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references