Uneven, Brittle, Uneven, Brittle, Uneven
Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Conchoidal
(K,Na)Ca4Si8O20(F,OH)•8(H2O)
PbCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references