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