Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Gemstones of the world (2001), Difficult, Splintery
NaFe3+3Fe3+6(BO 3) 3Si 6O 18(O,OH) 4Anthony et al , Handbook of Mineralogy (2001)
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Jadeite: NaAlSi2O6