Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
KCa 2AlBe 2Si 12O 30 · 0.5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)