ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
SiO 2(+Al 2O 3)Walter Schumann , Gemstones of the world (2001)
Al 4(Ta,Nb) 3(O,OH,F) 14Ulrich Henn and Claudio C.