A rapid procedure suitable for the routine determination of 1–10 ng of bismuth in a silicate rock matrix is described. Results for the U.S. Geological Survey standard rocks are presented. Rocks and minerals are dissolved in hydrofluoric-perchloric acid in the presence of 207Bi tracer and the silica is removed by evaporation. The perchloric acid residue is taken up in water and bismuth iodide is extracted into methyl isobutyl ketone. After three acid-iodide washes, the bismuth is stripped into water and reacted with a substoichiometric amount of EDTA. Excess of bismuth is extracted as the iodide and the specific activity of the bismuth-EDTA complex is determined.
