Lapis lazuli, also known simply as “lapis,” is a blue metamorphic rock that has been used by people as a gemstone, sculpting material, pigment, and ornamental material for thousands of years. High quality lapis lazuli can be a costly gem. The most desirable specimens have a rich, solid blue color and perhaps a few reflective pieces of gold pyrite.
Unlike most other gem materials, lapis lazuli is not a mineral. Instead, it is a rock composed of multiple minerals. The blue color of lapis lazuli is mainly derived from the presence of lazurite, a blue silicate mineral of the sodalite group with a chemical composition of (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2