Review of gold and platinum group element (PGE) indicator minerals methods for surficial sediment sampling

For gold deposits, varying combinations of gold grains, sulphides, platinum-group minerals (PGM), tellurides, scheelite and rutile, and some secondary minerals are useful indicator minerals depending on the deposit type, bedrock geology and weathering regime. Gold grain size, shape, and chemical composition for a variety of sediment types, including stream and glacial sediments, have been documented and the data used to determine potential source rocks and distance of transport. Useful indicator minerals for PGE deposits include those oxide and silicate minerals that indicate the host rocks and PGM, gold, sulphides, arsenides and antimonide minerals that indicate mineralization. Composition and morphology of PGM also have been well documented and this information is used to determine their genesis, potential source rocks and transport distance. Gold grains have been recovered from glacial and stream sediments for more than 100 years. PGM grains have a similar long history of recovery from streams, but only a few cases of recovery from glacial sediment have been reported. Research has focused on the development of microchemical characterization techniques for placer gold and PGM, while the focus for indicator minerals from glacial sediments has been the characterization of oxide and silicate suites.