Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)8Al6Si6O24(S,SO)4
KNa 2(Fe3+ ,Mn3+ ,Al) 2Li 3Si 12O 30Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references