ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
UnevenAnthony et al, Handbook of mineralogy (2001), UnevenAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Al 2Be 3Si 6O 18Martin H.
CaMoO 4Michael OâDonoghue , Gems, Sixth Edition (2006)