Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Gemstones of the world (2001), Difficult, Splintery
Ca 9(Mg,Fe2+ )(PO 4) 6(PO 3OH)Anthony et al , Handbook of mineralogy (2001)
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Jadeite: NaAlSi2O6