Uneven, Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001)
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Ca2Al3(SiO4)3(OH)
Al 4(Ta,Nb) 3(O,OH,F) 14Ulrich Henn and Claudio C.