Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal
Gemstones of the world (2001), Difficult, Splintery
(Mg,Fe2+ ) 7(SiO 4) 3(F,OH) 2Anthony et al , Handbook of mineralogy (2001)
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Jadeite: NaAlSi2O6