Ultramarine

n.
  1. A blue pigment formerly obtained by powdering lapis lazuli, but now produced in large quantities by fusing together silica, alumina, soda, and sulphur, thus forming a glass, colored blue by the sodium polysulphides made in the fusion. Also used adjectively.
    2. Green ultramarine ,
    a green pigment obtained as a first product in the manufacture of ultramarine, into which it is changed by subsequent treatment.
    Ultramarine ash or Ultramarine ashes (Paint.),
    a pigment which is the residuum of lapis lazuli after the ultramarine has been extracted. It was used by the old masters as a middle or neutral tint for flesh, skies, and draperies, being of a purer and tenderer gray than that produced by the mixture of more positive colors.