ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Uneven
Conchoidal, Brittle
(Mn2+ ,Fe2+ ,Mg,Ca) 2(PO 4)(F,OH)Michael OâDonoghue , Gems, Sixth Edition (2006)
(Mn2+ ,Fe2+ ,Mg)(Fe3+ ,Mn3+ ) 2O 4Anthony et al , Handbook of mineralogy (2001)