Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Splintery, UnevenArthur Thomas, Difficult, Fibrous
KCa 2AlBe 2Si 12O 30 · 0.5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
NaAlSi 2O 6Ulrich Henn and Claudio C.