Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Uneven, Uneven, Conchoidal, Uneven, Gems, Sixth Edition (2006)
{0001} Imperfect, {1120} Imperfect
Perfect on {001}, good on {010}
KCa 2AlBe 2Si 12O 30 · 0.5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Na,Ca)Al1-2Si3-2O8