Mother-of-pearl is not inherently a precious or ornamental stone -- it is a biolite, pseudo-mineral formed by biological organisms, in this case mollusks. They line the inner surface of their shells with it, gradually building up layer after layer throughout their lives. Mother-of pearl that is the 'progenitor' of pearls. Mother-of-pearl is a thin plate formed from layers of calcium carbonate (layer thickness less than 0.5 micron). Elastic polymers separate the calcium carbonate layers. This structure explains the extraordinary shimmers formed on the surface of the natural material. Mother-of-pearl comes from both the sea and rivers. It is come from the bottoms of lakes and rivers with gentle stream. Surprisingly, freshwater mother-of-pearl "grows" even in flooded rice paddies.

Archaeological excavations revealed that mother-of-pearl was known since the Pharaohs of ancient Egypt. It was found in the tombs of ancient rulers. Mother-of-pearl was raised in ancient Rome and India and is mentioned in the Koran and the Old Testament. One of the oldest jewellery was the unusual piece of mother-of-pearl found in what is now Iran, it is believed to be created as early as seven thousand years ago.
In Oriental countries, the mineral was used to decorate palace walls, utensils and household objects. White mother-of-pearl was the most commonly used. In the East, stone was used to decorate palace walls, utensils and household objects. The most common use was for white mother-of-pearl. Ancient doctors used the mineral as an antiseptic. It was supposed to help in healing wounds. In the Middle Ages, mother-of-pearl was ground into powder and used to make medicinal tinctures.

The development of mother-of-pearl the processing in European countries began in the 15th century, after the Crusades. Primarily the interest in this material grew up Italy, than the Netherlands, Germany and France followed it.

The first mentions of pearl and mother-of-pearl in Russia date back to the 10th century. At that time mother-of-pearl was simply called "shell".
The picked artisans used mother-of-pearl to create high status, elite items both of clerical and secular character.
The Russian North was rich in river pearl shells. Their thin rainbow layer was too fragile for carving, but well suited for finishing works. Chopped mother-of-pearl was implemented along with river pearls. The abundance of pearls and mother-of-pearl and the beauty of this natural material influenced the formation of the traditional Russian folk costume aesthetics. Affordable and relatively inexpensive, mother-of-pearl, along with beads and bugles, was used to decorate clothing and to master jewellery -- earrings, bead crochets necklaces and carcanets. Women headgear was embroidered particularly lavishly.
Mother-of-pearl was especially widely used in the arts and crafts all over the world, including Russia – to decorate jewellery, interiors, weapons, caskets and utensils. It was also used for the keys of musical instruments and in the traditional crafts (e.g. Fedoskino miniature). Pearl powder (a mixture of milled pearls and mother-of-pearl) is also used in the cosmetics industry to make creams, decorative cosmetics, toothpaste and sunscreeners.

In contemporary world mother-of-pearl is caught in the Persian Gulf, in the waters of the Red Sea, near Ceylon, Japan, Borneo, around the Philippines and on some islands in the tropical Pacific.
The colour of the stone, its purity and the number of shades depend on the habitat in which the mollusk lives. The quality of the animal feed influences the formation of the aragonite layer -- the finer it is, the brighter the chatoyment play of colors. The rarest and the most expensive colour of the mineral is gold, the color produced by the Manila clam, which lives on the bottom of the Indian Ocean.

Thematic photo album "Mother-of-pearl – one of the June mascots" is posted in the museum Photo Gallery

On the cover: Musical windmill shaped neсessaire. France, the 1820-1830s

Ref.:
https://jgems.ru/organicheskie/perlamutr
https://www.livemaster.ru/topic/3163081-perlamutr-i-kak-ego-nosit
https://kolechki-serezhki.ru/perlamutr-nedragoczennyj-chto-eto
https://moikamni.info/vidy/perlamutr