ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Ca 5(F,Cl)(PO 4) 3Arthur Thomas , Gemstones (2009)
Mg 2Si 2O 6Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references