抄録
Uranium estimation studies on muscovites occurring as pegmatites in the Bhilwara area, Rajasthan State (India) give an evidence of second-phase intrusions of uranium in the mica matrix. The uranium content of mica varies from 10−10 atom/atom to 10−5 atom/atom. The mean fission track age for this region was found to be 1069±51 m. y. The pegmatites are of Precambrian origin but the uranium inclusions belong to a much later stage in the geothermal history of the samples.
