Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Splintery, Brittle, Uneven
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references
NaCa 2(Mg 4Al)Si 6Al 2O 22(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)