Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Uneven
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
(Al,Mg) 8(Al,Si) 6O 20Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references