Uneven, Sub-Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
Uneven, Uneven, Management Team (2012), Conchoidal, Brittle
ZnCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Fe 3O 4Ulrich Henn and Claudio C.