Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Conchoidal
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
PbCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
PbCu(SO 4)(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)