Results of spectrometric U and Th determinations of a series of high-grade metamorphic rocks from a province in the north of Norway are given. The rocks tend to have low U and average Th contents as compared to plutonic rocks of similar bulk chemistry. High Th/U ratios characterize same red anatectic granites.

The spectrometric determinations of K are compared with earlier flame

photometric determinations and a satisfactory check is obtained.