pan for (something)
To attempt to find mineral deposits of precious metals (especially gold) by using a pan to separate them from the sand or stones in a river- or streambed. I heard he struck it rich panning for gold in the Rocky Mountains.
pan for something
to search for a precious metal, usually gold, by using a pan to locate the bits of metal in sand and gravel in a stream bed. When I was in Alaska, I panned for gold in a little stream set aside for tourists. The old prospector spent many hours panning for gold.