Sluicing is the use of a "sluice box" in a creek to separate gold from gravels.
A sluice box is a metal, wood, or plastic channel that has "riffles" and other devices in it to catch gold. The sluice box is placed in the water with the entrance of the box upstream, so water flows through the box. The sluice box is set with a slight downhill tilt, about 1 inch for every 3 feet of sluice box, so the water runs fast enough through the box to wash away the lighter gravels, but not so fast as to wash out the gold. A good visual measure of correct water speed is a "bubble" created over each riffle.
Gravels are shoveled into the top of the box where water enters. With the removal, by hand, of larger racks, the small pebbles and sands will be washed out. Black sand and gold will collect in front of the riffles. When you are finished shoveling for the day, the box is disassembled and emptied into a bucket or tub, which is then panned out.
Sluice boxes come in almost as many varieties as pans. Sluice boxes come in several lengths, from 52 inches down to about 30 inches. Obviously the larger the sluice box, the more gravels it can handle at a time. It will also need cleaning up less often. But, it is bulkier and heavier than smaller sluices. Some sluices can even be folded in two for backpacking.
Nowadays, sluice boxes are usually made of either aluminum or plastic. Aluminum is more durable than plastic, but can be damaged by bending it out of shape. Plastic, though not as durable as aluminum, is more forgiving to rough treatment (unless it becomes brittle and breaks), and is lighter in weight.
The aluminum sluice boxes will have a series of riffles, (generally called Hungarian Riffles) that can be removed or at least lifted to allow cleaning. Under the riffles, ribbed carpet or miner's moss is used to catch the fine gold. The old timers used burlap for this, and so can you. It still works just fine.
Plastic sluices generally don't have carpet. They use either molded riffles or molded traps in the bed of the box to catch the gold. Cleanup is fast and easy as their is no disassembly required. Understand that a 48 inch plastic sluice box is no toy. They are very efficient and very lightweight.
Sluicing is a great way to get started in recreational prospecting. They are a serious piece of equipment and have produced a lot of gold over the years. My suggestion is to get as large of a sluice box as you can afford and can handle based on you circumstances.
Prewitt & Company