Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Uneven, Subconchoidal, Uneven, Subconchoidal, Conchoidal, Brittle
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.
NaAlSi 2O 6 · H 2OMichael OâDonoghue , Gems, Sixth edition (2006) More from other references