Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001)
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Mg 2Al 4Si 5O 18Ulrich Henn and Claudio C.
BaTiSi 3O 9Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references