Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Gemstones of the world (2001), Difficult, Splintery
KCa 2AlBe 2Si 12O 30 · 0.5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Jadeite: NaAlSi2O6