Prospecting Methods - Mineralstar Mining

Gold Prospecting Methods

The gold pan is the most basic tool for use in gold prospecting. Although construction materials have changed over the centuries, the basic design, function, and method of use has remain unchanged. The gold pan works by separating materials by density, or specific gravity, whereby the more dense particles such as gold settle to the bottom of the pan while the lighter materials on top are sifted off layer by layer.

Use of the gold pan is simple at its rudimentary level, but technique can take time and practice to perfect. To begin, the pan is filled with paydirt from a suspected gold-bearing area. Next, the pan is submerged in the water and agitated in a circular motion. This turns the material into a suspended slurry which allows the gold to drop to the bottom. Then the pan is tilted partially submerged in the water and moved back and forth to remove the lighter material on the top. This process of slurrying the material and removing the lighter top layer is repeated until the heavy black sands and gold are all that remain in the pan.

Modern sluice boxes are usually made from aluminum or plastic that is molded into a U shaped channel with a set of riffles and carpet in the bottom. The box is set up in the course the stream with an even flow of water down the middle. Material is fed into the box at the upstream end, and the water moves it progressively down the box over the set of riffles. The gold, black sands, and other heavy components settle behind the riffles and into the carpet due to the eddying effect of the turbulent water and differences in specific gravity. When finished, the carpet and riffles are cleaned out and the concentrates are panned out to recover the gold.

A power sluice, or highbanker, uses the same principle as the the hand sluice. It adds efficiency to the process through the use of a hopper box where the material is washed and screened, which allows the larger rocks to pass out of the system and the smaller particles and gold run to through a sluice box. A water pump and hoses are required, but water permitting, the unit can be moved directly to the work location thereby eliminating the need to carry material long distances to a sluice box set up in the stream.

The suction dredge is a relative newcomer to the prospecting world, having only been used widely since the 1950s. The dredge is the ultimate gold-getting tool for recovery of stream-bound placer gold, because it allows the prospector to actually work gravels in the course of the active streambed. The dredge operates by forcing high pressure water from a pump through a venturi which causes a pressure differential that is harnessed with a suction hose allowing the prospector to literally vacuum the bottom of the river. The material is then passed through a sluice box on the surface for gold recovery.

Metal detectors are another tool that the old-timers didn’t have available to them. These units are able to locate gold by looking at a disturbance in a magnetic field that is picked up by the search coil. Detectors are mainly of use in prospecting areas that have potential for larger gold, such as river bedrock, hydraulic diggings, and tailings piles due to the particle size that the machine can detect.