What type of mineral resource is typically found using placer mining?

Placer mining is a specific method used to extract valuable minerals from alluvial deposits, which are often found in riverbeds, beaches, or other sedimentary environments. This technique is particularly effective for recovering minerals that have been concentrated by natural processes, primarily due to their high density. Gold is the most commonly associated mineral with placer mining because it is typically found in nuggets or flakes that accumulate in sediment.

The physical properties of gold, such as its density, make it easy to separate from lighter materials using techniques that exploit the differences in weight. As sediment is washed away by water, gold tends to remain due to its heaviness, leading to the formation of rich placer deposits.

While other materials like coal, iron ore, and sandstone can be mined through various methods, they do not typically occur in the types of deposits that placer mining targets. Coal is primarily extracted via underground or surface mining methods. Iron ore deposits are generally found in hard rock formations and require different extraction techniques. Sandstone is usually extracted for construction purposes and is not sought after through placer mining methods. Thus, gold stands out as the mineral resource most commonly recovered by placer mining activities.