Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references
Ca 3Al 2(SO 4)(F,OH) 10Ulrich Henn and Claudio C.