UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.
The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)8Al6Si6O24(S,SO)4