Gold panning and placer mining
Placer mining recovers loose gold from sand and gravel using water and gravity. Here is how a gold pan, sluice box and dredge work, and how to try panning responsibly.
The physics of placer gold
Placer mining works because gold is very heavy. At about 19.3 grams per cubic centimeter, it is roughly seven times denser than ordinary quartz sand. When water moves gravel, the light material gets carried along while gold sinks and stays behind. Every placer method, from a hand pan to a giant dredge, uses this one idea. For how placer deposits form, see gold in the Earth.
How to pan for gold
A gold pan is a shallow, sloped pan, usually plastic or steel, often with ridges called riffles on one side.
- Fill the pan about two-thirds with gravel from a promising spot, such as bedrock cracks or the inside of a river bend.
- Submerge it in calm water and break up clumps of clay and moss with your fingers.
- Shake the pan side to side under water. This lets heavy material, including gold, sink to the bottom.
- Remove big rocks after rinsing them over the pan.
- Tilt the pan forward and swirl, letting water wash the lightest top layer over the edge. Shake again regularly to keep gold settling.
- Repeat until only a small amount of heavy black sand (mostly magnetite) remains.
- Look for gold. Swirl a little water gently across the black sand and watch for flakes that stay yellow and bright in shade and sun. Pick them out with tweezers or a snuffer bottle.
Gold looks yellow from every angle and does not flash or sparkle like mica, and it bends rather than breaks if you press it with a pin. Pyrite (fool's gold) is brassy, forms crystals and crumbles.
Bigger tools
| Tool | How it works | Scale |
|---|---|---|
| Gold pan | Hand shaking and swirling | A few buckets an hour |
| Rocker (cradle) | A box rocked back and forth to wash gravel through a screen and riffles | More than a pan, one or two people |
| Sluice box | A trough with riffles and matting; flowing water carries gravel through and gold drops into the riffles | Many buckets an hour |
| Highbanker | A sluice fed by a pump, usable away from the water's edge | Small teams |
| Suction dredge | A floating engine and hose that vacuums streambed gravel into a sluice | Heavily restricted or banned in many places |
| Bucket-line dredge | A huge floating machine with a chain of buckets digging gravel | Industrial, historic in many regions |
| Wash plant | Trommels and jigs processing gravel dug by excavators | Modern commercial placer mines |
Modern commercial placer mining
Today most of the world's gold comes from hard-rock mines, but placer mining is still important in places such as the Yukon and Alaska, parts of South America, Africa and Asia. Commercial placer operations strip away overburden with excavators and bulldozers, feed pay gravel into wash plants, then refine the concentrate on shaking tables. Responsible operators settle muddy water in ponds before releasing it and reclaim the land afterward.
Mercury in small-scale placer mining
In many countries, small-scale miners mix mercury with gold-bearing sand. Mercury bonds with gold to form an amalgam, which they then heat to drive off the mercury as vapor. This releases toxic mercury into the air and rivers and seriously harms miners' health. Artisanal and small-scale gold mining is considered the largest source of human-caused mercury emissions. The international Minamata Convention on Mercury aims to reduce and, where feasible, eliminate this practice. See environmental impact.
Never use mercury to recover gold. It is toxic, and heating amalgam releases poisonous vapor.
Panning for fun, responsibly
Recreational panning is a popular hobby, and many parks, historic sites and gold-themed museums offer it. If you head out on your own:
- Check who owns or manages the land and the local rules. Mining claims are private rights even on public land in some countries, including the US.
- Respect seasonal restrictions that protect fish spawning.
- Fill in any holes you dig and leave the streambank as you found it.
- Watch for cold water, fast currents and unstable banks.
Most hobby panners find small flakes and tiny specks called "colors" rather than nuggets, and that is part of the fun. Next, follow gold into solid rock with hard-rock mining.
