Gemstones (2009), Flexible Flexible fragments.
Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001)
Al 2Si 4O 10(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Mg 2Al 4Si 5O 18Ulrich Henn and Claudio C.