Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, Brittle, Metallic, Brittle, Metallic
PbSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
NaNa2(Fe++4Fe+++)Si8O22(OH)2