ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
SiO 2Ulrich Henn and Claudio C.
Cu 3(OH) 2(CO 3) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references