UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.
KCa 2AlBe 2Si 12O 30 · 0.5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references