Sub-Conchoidal, Irregular/uneven, Sub-Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Brittle, Metallic, Brittle, Metallic
(Li,Na)Al(PO 4)(F,OH)Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Ca(Mg,Al)3(Al3Si)O10(OH)2