Uneven, Conchoidal, Brittle, Metallic, ConchoidalArthur Thomas, Gemstones (2009)
Subconchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Irregular
Ca 3Cr 2(SiO 4) 3Ulrich Henn and Claudio C.
SnO 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references