Uneven, Splintery, Conchoidal, Uneven, Splintery, Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001)
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
SiO 2Arthur Thomas , Gemstones (2009)
PbCu(SO 4)(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)