Lapis-lazuli - Natural minerals and crystals

Lapis lazuli is a metamorphic rock. Its characteristic blue color, often dotted with golden veins of pyrite, has made it a highly prized stone since ancient times. The intense blue color of lapis lazuli is mainly due to the presence of lazurite, a mineral from the feldspathoid group. This rock also contains other minerals such as calcite and pyrite. The formation of lapis lazuli is related to contact metamorphic processes. It usually forms in crystalline marbles, when limestone raw rocks and minerals">rocks are subjected to high temperatures and pressures in the presence of sodium-rich fluids. These conditions favor the formation of lazurite and other minerals constituting lapis lazuli. From a mineralogical point of view, lapis lazuli has a variable composition. The proportion of lazurite, calcite and pyrite can fluctuate from one sample to another, which explains the diversity of colors and patterns observed in this stone. Its physical and chemical properties, combined with its natural beauty, make it a precious stone used for centuries in jewelry and as a pigment for the arts.