Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Uneven, Brittle, Metallic, Brittle, Metallic, Brittle, Metallic
Perfect in three directions
Good on {110}, (110) ^ (1 1 0) ≈87°; parting on {100}
CuSiO 2(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Na,Fe,Ca)Si 2O 6Ulrich Henn and Claudio C.