Uneven, UnevenArthur Thomas, Gemstones (2009)
Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)
Pb 26Ag 10Cu 24Cl 62(OH) 48 · 3H 2OWalter Schumann , Gemstones of the world (2001) More from other references
The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)8Al6Si6O24(S,SO)4