Ichikazu Hayase

The minute radioactive minerals of the Gyoja-yama granite, Kyoto Prefecture

Radioactive minute mineals of the Gyoja-yama granite were studied with nuclear emulsion. Zircon, monazite, xenotiire and thorite were found as the origin of alpha radiations. The former two minerals were very abundant in this granite mass, especially in the contact zone. Generally, the minor minerals are more radioactive than the larger ones. The zonal radioactive heterogeneity is obvious from the alpha track distribution and from the optical property of one minute zircon crystal. This fact, we consider, may suggest the tendency of the radioactive material depositing in granite.