Placer mining is a method of mining that involves extracting minerals from unconsolidated surface deposits. It is typically done by manually digging or using a suction dredge. Placer mining is often used to extract gold, but it can also be used to extract other minerals, such as platinum, silver, and copper.

Placer mining is considered to be the least harmful to the environment because it does not require the use of heavy machinery or chemicals. It also does not create large amounts of waste. Placer mining can, however, have some negative impacts on the environment, such as:

* Habitat destruction: Placer mining can disrupt the habitat of fish and other aquatic life.

* Water pollution: Placer mining can release sediment and other pollutants into waterways.

* Erosion: Placer mining can cause erosion, which can lead to the loss of soil and nutrients.

Despite these potential negative impacts, placer mining is generally considered to be the least harmful to the environment compared to other mining methods.