Uneven-Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001)
Hackly Jagged, torn surfaces, (e.g. fractured metals)., torn surfaces, (e.g. fractured metals).
The chief constituent Lapis Lazuli is Lazurite, with the following chemical formula: (Na,Ca)8Al6Si6O24(S,SO)4
Cu