ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Conchoidal, Conchoidal, Gemstones of the world (2001)
CaBe 2(PO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006)
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)