Subconchoidal, Uneven, Conchoidal, Uneven
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Mn2+ Al(PO 4)(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references