Size, form and composition of gold grains in glacial drift in Ilomantsi, eastern Finland

Gold grains were studied in 102 till and gravel samples from an area with Au anomalies in the fine fraction of till. The form and size of gold nuggets were studied under the microscope, and the composition of selected grains was determined on a microprobe. The number of visible nuggets per sample was less than 10 per 81. In size, the nuggets were between 0.07 and 1 mm. Most of them were indefinite but flat in form, although idiomorphic gains were also observed. In composition, the gold grains in bedrock differed somewhat from those in till and gravel. Some of the nuggets found in gravel and in till were probably secondary in origin. The possibility that all the grains are not primary is emphasized in the interpretation of geochemical results.