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