Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Brittle, Uneven, Brittle, Uneven
CuSiO 2(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
NaCa16Si23AlO60(OH)8•64(H2O)