ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Uneven
Uneven
(Mn2+ ,Fe2+ ,Mg,Ca) 2(PO 4)(F,OH)Michael OâDonoghue , Gems, Sixth Edition (2006)
(Fe2+ ,Mg)Al 2(PO 4) 2(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)