Can sand metal and diamonds be mined from placer deposits?

Apparently alluvial diamonds migrate into placer deposits, being moved there by natural means, such as flowing water. Other materials are simply ground into tiny bits and ultimately 'placed' into the low spots in the geography.

Sand is a descriptor used to name the quality of the tiny stones that make up most of the materials in placer deposits: some metal bits and alluvial diamonds are also found in placer deposits.

You can read more about them, below.