URANIUM, THORIUM AND POTASSIUM CONTENT OF ROCKS IN JAPAN (2)

The content of uranium, thorium and potassium of 61 rock samples from Shikoku District has been determined by using the gamma-ray spectrometric, fluorometric or flamephotometric method.From the results the mean values or ranges are shown in Table 2.The mean values of radioactive elements of rocks from Shikoku District are fairly less than those from various regions in the world.As to the samples in radioactive disequilibrium, uranium determinations by two independent methods were carried out and the types of radioactive disequilibrium were classified by the results of the determinations by the gamma-ray spectrometry. The relations between the ratios of eq. U/U and the types of radioactive disequilibrium may suggest the adequacy of these classification of disequilbrium types.