Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
Subconchoidal, Uneven, Conchoidal, Uneven
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references
Mn2+ Al(PO 4)(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)