Note: Information is dated. Do not rely on it.Mother of Pearl, or Nacre. The hard, silvery, brilliant, internal or nacreous layer of several kinds of shells, particularly of the oyster family, often variegated with changing purple and azure colors. It is destitute of coloring matter, but is composed of a series of minute and slightly imbricated layers or ridges which have the power of decomposing the rays of light, thus producing beautiful iridescent hues. The large oysters of the tropical seas produce the best nacre; but, shells suitable for certain manufacturing purposes are obtained in fresh waters, particularly in the Mississippi and its tributaries. Mother-of-pearl is extensively used in the arts, particularly in inlaid work, and in the manufacture of handles for knives, buttons, toys, snuffboxes, etc.