Placer deposits are accumulations of valuable minerals, such as gold, silver, or gemstones, that have been concentrated by natural processes, typically through the action of water. These deposits form in riverbeds, beaches, or other sedimentary environments where the movement of water separates heavier minerals from lighter materials, allowing them to settle in specific areas. Mining placer deposits often involves techniques like panning, sluicing, or dredging, which help extract the concentrated minerals from the surrounding sediment. This type of mining is usually less invasive than traditional hard rock mining and can be done on a smaller scale, making it accessible for individual prospectors and small operations.