PARTICLE-SIZE AND ABUNDANCE OF GOLD IN SELECTED STREAM SEDIMENTS, SOUTHERN BRITISH-COLUMBIA, CANADA

Abundance of gold has been determined by neutron activation in six size fractions of sediments from five streams draining known gold occurrences in southern British Columbia. Analytical results and visual examination of heavy mineral separates have then been used to calculate the number of particles of free gold in each fraction. These estimates, considered in relation to sampling statistics based on the Poisson distribution, demonstrate the difficulty of collecting an adequate field sample and reducing it to an acceptable subsample small enough to be analyzed conveniently. More favorable sampling statistics are found with the original minus 53 mu fraction, for which a 20-kg minus 4-mesh (5 mm) field sample will usually suffice to provide a representative sediment sample that can be analyzed directly without the necessity of preparing a heavy mineral concentrate.