ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Gemstones of the world (2001), Difficult, Splintery
SiO 2Walter Schumann , Gemstones of the world (2001)
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Jadeite: NaAlSi2O6