Panning
Gold panning was commonly used on its own during the California gold rush, however it is now rarely used for profit since even an expert gold prospector can only process approximately one cubic yard of material for every 10 hours of work
Rocker Box
A rocker box (or “cradle”) is capable of greater volume than a gold pan, however its production is still limited when compared to other methods of placer mining. It is only capable of processing about 3 or 4 yards of gravel a day
Sluice Box
While they are capable of handling a larger volume of material than simpler methods such as the rocker box or gold panning, this can come at the cost of efficiency, since conventional sluice boxes have been found to recover only about 40% of the gold that they process.
Dry Washing
Sluicing is only effective in areas where there is a sufficient water supply. Alternative methods developed that used the blowing of air to separate out gold from sand. Dry wash technique varies from 1 1/2 to 4 cubic yards per day, and can be processed at a maximum efficiency of 80%.
Trommel
A trommel is composed of a slightly-inclined rotating metal tube with a screen at its discharge end. The ore is fed into the elevated end of the trommel. Water, often under pressure, is provided to the scrubber and screen sections and the combination of water and mechanical action frees the valuable minerals from the ore. The mineral bearing ore that passes through the screen is then further concentrated in smaller devices such as sluices and jigs. The larger pieces of ore that do not pass through the screen can be carried to a waste stack by a conveyor.
Gold dredge
Large-scale sifting of placer gold from large volumes of alluvial deposits can be done by use of mechanical dredges. These dredges were originally very large boats capable of processing massive amounts of material, however as the gold has become increasingly depleted in the most easily accessible areas, smaller and more maneuverable dredges have become much more common.