Define placer deposits, and explain how placer deposits form?

Placer deposits can be described as the accumulation of heavy minerals. The placer deposits are known to be formed by the effects of gravity on moving rocks.

By the process known as weathering, the heavy, valuable minerals are separated and are washed into streams. The mineral which forms by the process of placer deposit is resistant to weathering and high gravity.

Examples of these placer deposit minerals include gold, platinum etc.