Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
PbSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
SiCArthur Thomas , Gemstones (2009)