Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
SiCArthur Thomas , Gemstones (2009)
Mg 2Si 2O 6Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references