Uneven, Conchoidal, Brittle
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
(Na,Ca)4-8Al6Si6(O,S)24(SO4,Cl)1-2
PbSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references