Conchoidal, Splintery, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
AlPO4 · 2(H2O)
(Zn,Mn2+ )OMichael OâDonoghue , Gems, Sixth Edition (2006)