Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)8Al6Si6O24(S,SO)4
Al 2SiO 5Arthur Thomas , Gemstones (2009)