Uneven, Sub-Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
ZnCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Zn,Mn2+ )OMichael OâDonoghue , Gems, Sixth Edition (2006)