Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
SiCArthur Thomas , Gemstones (2009)
MgCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references