Sub-Conchoidal, Irregular/uneven, Sub-Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
(Li,Na)Al(PO 4)(F,OH)Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.