ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Gems, Sixth Edition (2006), Gems, Sixth Edition (2006)
(Cs,K,Rb)Al 4Be 4(B,Be) 12O 28Anthony et al , Handbook of mineralogy (2001)
SiO 2Michael OâDonoghue , Gems, Sixth Edition (2006)