The development of the mining industry and the level of development of mining technologies can be traced through the example of mica. Justification, carried out in the northwest of the Karelian-Kola region, which lasts for many centuries. The traditional source of mica-muscovite since ancient times was mica pegmatites, developed in the Chupino-Louhi region and on the Kola Peninsula. Since the middle of the XVIII century, in connection with the spread of factory glass, the fishing of the \"sulphurous stone\" is declining, but in Belomorye mica in everyday life was used everywhere until the second half of the XIX century. The study of muscovite specimens from the archaeological excavation of the destroyed Church of the Nativity of the Most-Pure Mother of God of the Kandalaksha Monastery shows that muscovite is close to the mica of the Yen deposit. This indicates that the mica mining region in the late Middle Ages was more extensive than previously thought, and included objects on the Kola Peninsula.