placer mining

/ˌpleɪsər maɪnɪŋ/

Using water to extract minerals is called placer mining. This method is used to find valuable deposits of metals, like gold and platinum, that collect in stream beds.

Placer mining is an ancient technique of extracting precious metals from placer deposits, concentrations of heavy minerals caused by gravity. The most basic form of placer mining is panning for gold (or other minerals), scooping deposits from a creek bed along with water and sifting through them in search of heavy, shiny pieces that might be valuable. Placer is a Spanish word meaning "shoal" or "sand deposit."

Definitions of placer mining

1. noun

   mining valuable minerals from a placer by washing or dredging
   type of:

   excavation, mining

   the act of extracting ores or coal etc from the earth