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