Mother-of-pearl, also called nacre, is the iridescent substance (see iridescence)
of which pearls and the inner coating of bivalve mollusc shells are made. It consists of alternate thin layers of aragonite (calcium carbonate) and conchiolin, a horny substance. Mother-of-pearl is
valued for its beauty, and is used in thin sheets for ornament, jewelry,
and buttons. See also abalone.
|The inner mother-of-pearl (nacre) layer of the abalone
shell. Image credit: University of California, Riverside, Bourns College