Belomorite (Russian: Беломори́т — from the toponym),[2] sometimes peristerite or moonstone, also murchisonite, Ceylon opal, hecatolite — a decorative variety of albite (oligoclase) of white or light gray color with a distinct iridescence effect.

The best varieties of belomorite are translucent or transparent, they have a pearl-glass luster and iridescence in blue, gray-blue, violet-blue, greenish-blue or pale violet tones.

However, due to its fragility and perfect cleavage, the mineral often breaks and is difficult to process, so it is cut in the form of simple cabochons (oval, round, teardrop-shaped), as well as balls or polished plates.

A decade and a half after the discovery of this variety of albite near the White Sea coast, Alexander Fersman described the history of his “find” in sufficient detail and accurately in a short lyrical essay entitled “Belomorite.” Together with his companion, he got off the train at the Arctic Circle station [ru] in the Loukhsky District of the Republic of Karelia and they set off together towards the “Blue Pale” — that was the name of the mined-out vein of feldspars, located in the middle of a swampy area, between hills (in Karelian - varaks) almost on the very shore of the White Sea, about six kilometers east of the station.

[3] Meanwhile, the authors of the “new mineral” did not insist that they had made some kind of mineralogical discovery, noting that the decorative variety of stone received from them a new poetic name or even a trademark.

[3] It must be remembered that the coast and, more broadly speaking, the environs of the White Sea are by no means the only place where Fersmanovsky belomorite, which belongs to the class of perhaps the most common rock-forming minerals on earth, reveals itself.

Deposits of this type of plagioclase, most often associated with mica-bearing and ceramic pegmatites, are located in other places in North Karelia (the vicinity of Khetolambina [ru], Mica Bor), as well as in the south of the Kola Peninsula.

This effect is associated with the scattering of white light by very small submicroscopic point defects in the structure of the stone such as microperthite ingrowths, thin cleavage plates or spatial fluctuations in the internal composition.

[11] In addition, local deposits of iridescent albite are known in Australia, Austria, Germany, Italy, Kenya, Norway, Poland, Ukraine, as well as in France, Switzerland, Sweden and Japan.

As a result, the mineral often breaks and is difficult to produce, also for this reason it is most often cut in the form of simple cabochons (oval, round, teardrop-shaped), as well as balls, taking into account existing cracks and cleavage lines.