Conchoidal, Gems
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
NaAl 3(PO 4) 2(OH) 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Ca,Na)(Mg,Fe,Al,Ti)(Si,Al) 2O 6Anthony et al , Handbook of mineralogy (2001)