Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, Brittle, Metallic
PbSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
CuFeS 2Anthony et al , Handbook of mineralogy (2001)