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