The chemical composition and age of the accessory uraninite from the desilicated plagioclasites of the Lipovsky vein field is given in the work. According to chemical dating, uraninite showed 2 ages – Upper Permian and Middle Triassic. In normal plagioclasites, uranium oxide yielded 257 ± 6 Ma, and in tectonized – 245 ± 7 Ma. From this it follows that in the Upper Permian time, under the influence of the heat flux (most likely, with the introduction of lithic veins), the usual pegmatites lying in the ultrabasites were transformed into plagioclasites. In the Middle Triassic time, plagioclasites underwent secondary transformations (with associated tectonic movements) during the formation of young pegmatites of the Aduisky granite massif.