UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
BaCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
PbCu(SO 4)(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)