Subconchoidal, Uneven, Conchoidal, Uneven
Uneven, UnevenArthur Thomas, Gemstones (2009), Brittle
Mn2+ Al(PO 4)(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)
MnPO 4Walter Schumann , Gemstones of the world (2001) More from other references