Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Mg 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)
SiO 2Ulrich Henn and Claudio C.