Uneven, Uneven, Management Team (2012), Conchoidal, Brittle
Subconchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Irregular
Fe 3O 4Ulrich Henn and Claudio C.
SnO 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references