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