Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)
Uneven, Splintery, Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001)
The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)8Al6Si6O24(S,SO)4
SiO2