Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Uneven
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.
Mn 3B 7O 13ClMichael OâDonoghue , Gems, Sixth Edition (2006)