Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
{0001} Imperfect, {1120} Imperfect
Perfect on {010}, good on {100}
KCa 2AlBe 2Si 12O 30 · 0.5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Be 2BO 3(OH)Ulrich Henn and Claudio C.