ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Uneven
Gemstones of the world (2001), UnevenWalter Schumann, Gemstones of the world (2001)
Zn 2(Fe2+ ,Mn2+ )(PO 4) 2 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
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