Gemstones of the world (2001), Difficult, Splintery
Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Jadeite: NaAlSi2O6
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references