Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.
(Cs,K,Rb)Al 4Be 4(B,Be) 12O 28Anthony et al , Handbook of mineralogy (2001)