Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.
Ca 2B 5SiO 9(OH) 5Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references