The usual size of the gold pan is about 14 inches that will hold about 20 pounds of gravel. Although you can take the gravel straight from the streambed it makes panning much easier if you use a classifier that removes all the stones larger than 3/8 of an inch from the gravel before you start panning. It is a good idea to examine these larger stones just to see if there are any gold nuggets present that might be thrown away with the oversized stone.
|Gravel the largest piece in this picture in about 4 cm. This is typical of gold bearing gravel.|
Photo by Stan Zurek
Gold is 19 times the density of water meaning that by shaking the gold pan combined with a circular motion when it is full of water will cause gold particles to settle through the gravel to the bottom of the pan. This is a process that you will want to repeat several times in the process of panning.
The gold pan is held at an angle so it's lower edge is submerged in water allowing the gravel to slowly pour over the rim and back into the stream. Periodically remove the pan from the stream and repeat the swirling motion to be sure you don't lose any of gold. Keep repeating this process until all that is left in your pan is an accumulation of black sand. It is in this black sand where gold accumulates. Always keep the edge of pan having the riffles submerged because the gold will be caught in the riffles rather than poring over the edge of the pan.
|Gold panning showing how to hold a gold pan. USDA|
For the most part black sand is an accumulation of magnetite and hematite that our oxides of iron. Magnetite can be removed using a conventional magnet: hematite can be removed using a rare earth magnet. The magnetic separation of the iron oxides leaves behind a concentrate of the other heavy minerals that are found in stream gravel the most common of which are garnet and zircon as well as any other gold particles and other precious metals such as platinum. Gold and platinum often occur together!