Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Mg 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)
CaBePO 4(F,OH)Ulrich Henn and Claudio C.