Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Al 4(Ta,Nb) 3(O,OH,F) 14Ulrich Henn and Claudio C.