Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Conchoidal, Brittle, Conchoidal
CaB 2(SiO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
[ ]Na2(Mg3Al2)Si8O22(OH)2