Azurite (pigment)

Blue dye and pigment made from the mineral azurite, a deep blue mineral composed of basic copper carbonate that is naturally found adjacent to the green copper carbonate mineral malachite. Azurite is prepared as a pigment by careful selection, grinding, washing, and levigation, with the coarsely ground azurite giving a deeper blue color and finely ground particles giving a lighter more transparent tone. Azurite is lightfast but is sensitive to acids and sulfur fumes; it is used for paints and dying luxury fabrics.