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