Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)
Al 4(Ta,Nb) 3(O,OH,F) 14Ulrich Henn and Claudio C.