Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Conchoidal, Metallic, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.
Cu 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references