Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle
The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)8Al6Si6O24(S,SO)4
(Be,Cs) 3Al 2Si 6O 18 · 0.5H 2OUlrich Henn and Claudio C.