ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)
PbCu(SO 4)(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)