ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Uneven, Uneven, Gems, Sixth Edition (2006), Uneven, Conchoidal
CaTiSiO 5Ulrich Henn and Claudio C.
NaAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)