A sluice box is among the oldest tools used by gold prospectors. It makes use of the fact that gold is heavier than other materials. The sluice box is usually a wooden or metal trough that materials are shovelled into while water washes through the assembly. The water carries away the lighter materials while depositing the gold in the bottom of the sluice box. The proper design and construction of the sluice box improves the efficiency of the operation.
Build the frame of the sluice box out of treated lumber or metal. Typical sluice boxes are between 90 cm and 1.8 metres (3 and 6 feet) long and about 45 cm (18 inches) wide. Extend the sides about 15 cm (6 inches) above the floor of the sluice box. Aluminium sluice boxes are light and easy to use but require special tools to cut and bend that many home craftsman won’t have. Wood boxes should be built using treated lumber fastened together with galvanised 75-mm (3-inch) deck screws.
Add riffles to the bottom of the sluice box. According to the website Nevada Outback Gems the best riffles are slats of steel welded to a framework that places them at about a 45 degree angle to the floor of the sluice box with the low edge of the steel piece closest to the top of the sluice box. This riffle assembly needs to be removable to give the prospector access to the accumulated gold.
Line the bottom of the sluice with rubber mats or miners moss. These items are available from prospectors' supply stores in gold country and online. Make these items removable to allow the gathering of gold, which may accumulate in the sluice box. The moss or mat is held in place by the metal riffles.
Operate the gold sluice box by placing it in flowing water. Angle the sluice box so the bottom is 2.5 to 5 cm (1 to 2 inches) lower than the top for each foot of the sluice box's length. Shovel what is thought to be gold-bearing gravel into the top part of the sluice box and allow the water to wash the mix through the sluice box. Remove large rocks by hand. Remove the riffles and mat or moss periodically and clear all the heavy materials they hold for processing with a gold pan.
Sluice boxes can be almost any size or dimension and made of most any material the builder has the tools and skills to work with. Design a box that you can handle and move about as necessary and is transportable in your car or truck.