Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Sub-Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references
ZnCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references