Geochemical surveys are undertaken to generate target areas for further exploration. The surveys usually involve the collection of soil, rock and/or sediment samples. These samples are sent for laboratory analysis to identify areas of potential mineralization. The surveys may comprise:
Soil sampling: Hand-held tools such as shovels, picks and hand augers are used to collect samples of soil and subsoil. Samples are typically collected on a regular grid pattern and involve collection of small (approximately one kilogram) samples of soil. Power augers, either hand operated or vehicle-mounted, may be used.
Stream sediment sampling: Approximately two-kilogram samples of sediment are collected within drainage lines. Three samples are usually taken at the junction of two creeks: one downstream of the junction and two upstream of the junctions (in each of the merging drainage lines). Samples are typically extracted using hand tools and may be sieved during collection.
Rock chip sampling: Up to a few kilograms of rock material from outcrops are collected using hand-held tools. Rock chip samples will usually be collected during geological mapping programs.
Channel sampling: A series of samples of soil or rock are collected along the face of the excavation. This may be a road cutting, the face of an open-cut or underground mine, a trench or similar.