ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Uneven, Conchoidal, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle
SiO 2Walter Schumann , Gemstones of the world (2001)
FeS 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references