Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)
Gemstones of the world (2001), Difficult, Splintery
The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)8Al6Si6O24(S,SO)4
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Jadeite: NaAlSi2O6