ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)
SiO 2(+Al 2O 3)Walter Schumann , Gemstones of the world (2001)
The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)8Al6Si6O24(S,SO)4