Uneven, Uneven, Gems, Sixth Edition (2006)
Uneven, Uneven, Irregular, Management Team (2012), Conchoidal, Brittle
Al 2O 3Michael OâDonoghue , Gems, Sixth Edition (2006)
Ca 3Al 2(SiO 4) 3-x(OH) 4x (x=0.2 to 1.5)Anthony et al , Handbook of mineralogy (2001)