Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
SiCArthur Thomas , Gemstones (2009)
Fe 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)