Mother of Pearl

Mother-of-Pearl, hard, iridescent inner layer of certain shells, such as that of the abalone, pearl oyster, and mussel. Also called nacre, mother-of-pearl is composed chiefly of calcium carbonate deposited in thin, overlapping layers, together with some organic matter. The iridescent play of colors for which mother-of-pearl is known is caused by the interference of reflected light waves. In both Eastern and Western cultures, mother-of-pearl has a long history of use in decorative finishes and inlays for furniture, boxes, jewelry, buttons, and other ornamental objects.