LIU, YZ (reprint author), UNIV ELECTROCOMMUN,DEPT CHEM,CHOFU 1-5-1,TOKYO 182,JAPAN.
Thorium concentrations in 11 native gold samples from different sources, e.g. placer gold, vein and lode gold were determined. Thorium was determined by radiochemical separation and measurement of protactinium from irradiated native gold samples. The chemical yield of the separation procedures is 90%. Other elements were measured by gamma-ray spectroscopy. The radiochemical separation procedures described in this work make accurate determination of Th concentrations in native gold at picogram concentrations possible.