Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
Uneven, Splintery, Conchoidal, Uneven, Splintery, Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001)
Mg 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)
SiO 2Arthur Thomas , Gemstones (2009)