Placer deposit

In geology, a placer deposit is a deposit of earth, sand, or gravel, containing valuable minerals in particles, especially by the side of a river, or in the bed of a mountain stream. Placers may also be found at the oceanside, deposited by the action of waves.

Placer mining is an important source of gold, and was the main technique used in the early years of the California Gold Rush[?]. The name is from the Spanish word placer, meaning "pleasure", because placer mining is much easier than pick-and-shovel mining.