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April 25, 2017

Whether you pan for gold or rare earths, you’ll get a lot of sand...and this EarthWord!

EarthWords is an on-going series in which we shed some light on the complicated, often difficult-to-pronounce language of science. Think of us as your terminology tour-guides, and meet us back here every week for a new word!

Image shows black pans with gold grains
Gold Pans and Placer Gold - image by  California Geological Survey.

The EarthWord: Placer


  • If you’re panning for gold, you’ve come to the right place-r, that is! Placers are a type of mineral deposit in which grains of a valuable mineral like gold or the rare earths are mixed with sand deposited by a river or glacier.

  • Placer is also a mining method term. Placer mining uses water and gravity to separate gold from surrounding material.


  • Placer is an Americanization of the Catalan word placel, which itself came from the Spanish word plaza, meaning “open space.”

Use/Significance in the Earth Science Community:

  • Placer deposits containing gold are areas that have highly concentrated accumulations due to stream/river erosional processes taking place around/over geologic terranes that contain gold, over a very long period of time.

  • Placer deposits are an important source of many valuable minerals, particularly gold and rare earth elements. They occur throughout the world.


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Hungry for some science, but you don’t have time for a full-course research plate? Then check out USGS Science Snippets, our snack-sized science series that focuses on the fun, weird, and fascinating stories of USGS science.