Uneven, Sub-Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
ZnCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Ca,Mg,Mn)SiO 3Gemdat.org , Management Team (2012)