Irregular, Irregular, Gemstones of the world (2001)
Subconchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Conchoidal
CaCO 3Ulrich Henn and Claudio C.
LiAlSi 4O 10Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references