The physicochemical parameters, vegetation and biodiversity of microbiomes inhabiting 10-, 35- and 50-year-old embryonic soils (technozems) formed in the mining areas of the Kursk Magnetic Anomaly (Russia) were analyzed in the current study. Analysis of taxonomic diversity was carried out by 454-pyrosequencing of the V4 variable region of the 16S rRNA gene. All points of the chronosequence were characterized by microbiomes reliably differing in taxonomic composition. The older the dump, the higher the proportion of bacteria from the phyla Actinobacteria (mostly representatives of the Solirubrobacteriaceae family), Chloroflexi and Acidobacteria in the community. In 10-year-old dumps, bacteria from the phyla Proteobacteria, Gemmatimonadetes and Bacteroides prevailed. The most pronounced changes in the community structure at the early and middle stages of microbiological succession were demonstrated by bacteria from the genus Delftia, which may indicate their active role in the processes of soil formation in this ecosystem.