Uneven, Uneven, Gems, Sixth Edition (2006)
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Al 2O 3Michael OâDonoghue , Gems, Sixth Edition (2006)
(Zn,Mn2+ ,Fe2+ )(Fe3+ ,Mn3+ ) 2O 4Anthony et al , Handbook of mineralogy (2001)