Subconchoidal, Uneven, Conchoidal, Uneven
Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Mn2+ Al(PO 4)(OH) 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)
Mg 2Si 2O 6Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references