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