Uneven, Brittle, Uneven, Brittle, Uneven
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Perfect on {001}, imperfect on {110}
[001] good, [210] distinct
(K,Na)Ca4Si8O20(F,OH)•8(H2O)
PbSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references