How to Use a Sluice Box: 7 Steps, Slopes and Riffles

A gold sluice works by sending water and gravel down a sloped trough fitted with riffles. Gold is about seven times as heavy as quartz sand, so it drops behind the riffles while lighter material washes out the end. To use a sluice box you set it in moving water at a slope of roughly 10 to 15 degrees, feed screened gravel slowly, clean out the concentrate when black sand reaches the lower riffles, and finish the concentrate in a gold pan with a swirling motion.

This guide answers how a gold sluice works and how to run one, with the setup numbers published by the British Geological Survey and the Washington Geological Survey, a table of settings for coarse and fine gold, the right way to swirl a pan during clean-up, and a calculator for what a day of sluicing could return at your own grade and gold price.

How does a gold sluice work?

A sluice is an inclined trough with bars or mats on the floor. The Washington Division of Geology and Earth Resources describes a sluice box as a sloping box whose riffles give gold and other heavy minerals a place to lodge, while water carries the gravel through. The whole method rests on density. Pure gold has a specific gravity of 19.3, according to the North Carolina Geological Survey. Specific gravity is how many times heavier a material is than the same volume of water. Quartz and other common silicate sand sit near 2.7.

Three things happen inside the box:

• Transport. Water and gravel enter the head of the box as a slurry. In a well-run sluice, water makes up 85% to 95% of the feed volume (British Geological Survey, 2002).
• Settling. Each riffle creates a small eddy behind it. The current slows there, and heavy grains sink while light grains stay in the flow.
• Trapping. Gold, magnetite and other heavy grains pack into the low-pressure zone behind each riffle and into the mat underneath. Light sand keeps moving and leaves as tailings.

The balance is delicate. If the water is too slow, sand fills the gaps between riffles and nothing more can settle. If it is too fast, it scours the riffles and fine gold leaves with the tailings. The BGS good-practice guide on sluice boxes gives a simple field test: when the speed is right, the sand between the riffles keeps moving and seems to dance; when it is too slow, the gaps clog.

▶ How gold is mined and refined, step by step, from rock to bar. · 5:27

Why gold settles and black sand settles with it

Gold is not the only heavy mineral in river gravel. Placer gold usually travels with black sand, a mix of dark heavy minerals such as magnetite, ilmenite, chromite, garnet and cassiterite (Washington Geological Survey). A placer is a deposit of loose sand and gravel in which heavy minerals have been concentrated by water. A lode, by contrast, is gold still held in solid rock such as a quartz vein.

Chart

Specific gravity of gold and common black-sand minerals

Times heavier than water; mean or upper listed value

The chart below shows why these minerals end up together in your riffles. All of them are well over the density of quartz sand, so the sluice treats them the same way. Gold is in a class of its own, which is why the final step of clean-up can separate it from the black sand in a pan.

Black sand is useful. The Washington survey notes that if you recovered black sand, you should also have caught any gold present, and it recommends cleaning up a short sluice when black sand starts to pass over the second and third riffles. A 2023 review of gravity concentration of heavy minerals lists sluices with jigs, spirals and shaking tables as the classic methods that separate minerals by their specific gravity.

Parts of a sluice box and common sizes

Hand sluices sold for prospecting look different, but they share the same parts:

• Head or flare. The wide upstream end where water and gravel enter. A flare helps catch more stream flow.
• Grizzly or classifier. A screen or set of bars across the head that rolls large rocks off to the side. The Washington survey says openings of up to about 1 inch are common.
• Riffles. Bars across the floor. Traditional boxes used wood strips placed 1 to several inches apart; modern ones use angle iron, expanded metal or moulded plastic.
• Matting. Carpet, rubber or vinyl matting under the riffles that holds fine grains. Older crews used burlap, blankets or miner’s moss.
• Tail. The outlet where tailings leave the box.

Sizes vary widely. The Washington survey reports sluice boxes from 6 inches to 6 feet wide. A common box is about 12 inches wide, 12 inches high and 12 feet long, while a prospecting box can be 8 inches wide, 6 inches high and as short as 4 feet. Larger operations join 12-foot sections end to end, and crude set-ups often use 3 to 6 boxes (30 to 72 feet). For high-throughput alluvial work, the BGS recommends that each riffled section be at least 3 metres (about 10 feet) long, and up to 5 metres.

Settings that matter: slope, water and riffles

Slope is the main adjustment you control on site. The BGS guide states that most sluice boxes run at around 10 to 15 degrees and that the final angle is tuned alongside the width, water flow and feed rate. Its guideline table separates two common trap types:

Chart

Recommended sluice slope by riffle type

Degrees from horizontal

Source: British Geological Survey, Good practice in the design and use of sluice boxes, Table 2 (2002).

Older North American guidance is expressed as drop per foot. The Washington survey reports common sluice grades of up to about 1 inch of drop per foot and says long toms are set at 1 to 1.5 inches per foot. It also says a sluice needs 7 to 13 times as much water as gravel to move loose sand and gravel through the box.

The BGS gives an easy way to check flow speed in the field: mark a known length along the box, drop a floating object into the stream and time it. Speed is the length divided by the time. Fine gold traps need a slower, shallower stream than coarse gold traps, so many boxes use a coarse section at the head and finer matting further down.

How to use a sluice box: seven steps

These steps follow the Washington survey and BGS guidance. Check the local rules first (see the permits section below).

Infographic

Running a sluice in 5 stages

1. 1TestPan samples to find gravel worth sluicing.
2. 2SetPlace the box in moving water at about 10 to 15 degrees.
3. 3ScreenRemove rocks and break up clay before feeding.
4. 4FeedAdd gravel slowly and watch the sand move between riffles.
5. 5Clean upWash the mat into a tub and pan the concentrate.

1. Test the ground with a pan

Pan a few samples from likely spots before you carry the box in. The Washington survey suggests working when water is low and bedrock is exposed, and avoiding swift water, potholes in bedrock and shallow-gradient streams whose current is too weak to move gold. The survey also notes that cracks and ribs in bedrock act as natural riffles that trap gold.

2. Place the box in moving water

Find a spot where the stream runs fast enough to fill the box without spilling over the sides. Set the head facing upstream, weight it with flat rocks, and make sure water enters evenly across the full width. A box that leans to one side sends the flow down one edge and loses gold.

3. Set the slope

Start in the 10 to 15 degree range the BGS gives, or at about 1 inch per foot for a short hand box. Adjust by raising or lowering the tail.

4. Screen the gravel

Classify your material before it reaches the riffles. Rocks crowd the riffles and create surges. The BGS screen table covers openings from 1 mm up to 25 mm (1 inch); a finer screen gives the riffles an easier, more even feed. Break up clay lumps in a tub first, because clay can roll fine gold out of the box.

5. Feed slowly and evenly

Add a small shovel or scoop at a time near the head, not all at once. A steady feed keeps the stream depth and speed stable. Two people shovelling by hand can put 10 to 15 cubic yards of loose sand and gravel through a sluice in a 10-hour shift, according to the Washington survey.

6. Watch the riffles

Look for the sand dancing between the riffles. If the gaps fill with packed sand, steepen the box or feed more slowly. If the riffles scour bare and you see black sand leaving the tail, lower the slope or reduce the flow. Clean up when black sand reaches the second and third riffles on a short box.

7. Clean up the concentrate

Stop feeding and let clear water run until the tops of the riffles are clean. Lift the box out level, or lift the riffles from the head end first while the concentrate stays on the floor, as the Washington survey describes. Roll the mat up and wash it out in a tub. The material in the tub is your concentrate, ready for panning.

Where the gold sits in the box

Most of the gold drops early. The BGS guide reports a study in which a sluice box was split into three equal parts from top to bottom: they held 90%, 9% and 1% of the gold recovered. The guide adds that this pattern held whether the box recovered as little as 30% or as much as 80% of the gold in the feed, so a rich head section does not prove the box is working well.

Chart

Share of recovered gold by third of the sluice

Percent of gold recovered, box split into three equal lengths

Fine gold is the weak point. A BGS study of small-scale miners in the Migori belt of Kenya found that gold there was mostly finer than 100 microns (0.1 mm) and that sluice recovery for gold of that size can fall as low as 20%. Its recommendations included longer sluice channels of at least 3 metres, suitable gradients, sizing the feed before it enters the box, and alternative gravity methods for the fine fraction. The USGS reported that at one Arizona placer about 10% of the gold recovered was finer than 100 mesh (about 0.15 mm) (USGS Bulletin 1355).

If fine gold matters at your site, the practical steps are a longer box, a finer mat at the tail, a slower and shallower flow over the fine section, and screening the feed into size classes before sluicing.

Gold panning technique: how to swirl properly

Clean-up ends in the pan. The Washington survey’s step-by-step panning method works the same for sluice concentrate as for raw gravel. Standard pans are 10, 12 and 16 inches across, and the survey says the 12-inch pan is probably the most widely used.

1. Fill and soak. Fill the pan nearly full, put it under water and mix with your hands until everything is wet and clay is broken up.
2. Shake flat. Under water, quickly shake the pan from side to side without tipping it. This lets heavy grains sink to the bottom.
3. Tilt and wash. Tilt the pan slightly away from you and use a gentle forward-and-back or circular motion so water carries the lighter top layer over the rim.
4. Repeat. Go back to shaking flat, then tilting and washing, adding water as needed, until only a small amount of heavy material covers part of the bottom.
5. Swirl the concentrate. Pour off most of the water, leaving just enough to cover the concentrate. Swirl the water slowly around the lower part of the pan so it washes over the concentrate. Lighter grains travel further than heavy ones, and the gold is left as a tail at the end of the black sand.
6. Pick up the gold. Lift flakes with a moist fingertip, a wet brush or a snuffer bottle and wash them into a vial of water.

The swirl is the step most people rush. Keep the motion slow, keep the pan tilted only slightly, and stop as soon as the tail of gold shows. A magnet in a plastic bag lifts magnetite out of dried concentrate, the survey notes, which makes the last separation easier.

The Washington survey also gives a time rule: if fine flakes keep leaving with the black sand, it is often better to save the black sand and finish it later than to spend a long time on one pan. Working quickly costs only the very smallest flakes.

Sluice, pan, rocker or long tom: how much material each handles

Method choice comes down to how much gravel you need to move. The figures below come from the Washington survey and assume loose, unconsolidated gravel over a 10-hour day.

On these figures a sluice moves roughly 8 to 12 times as much gravel per person as a pan, which is why it is the standard tool for steady creek work. For a wider look at the methods used on larger placer projects, see our guide to placer gold mining methods.

What a day of sluicing can return

Placer miners in Yukon measure ground by ounces per 100 loose cubic yards. In a September 2025 CBC report, people in the Yukon placer industry said miners once needed about 1 ounce per 100 yards to break even, and that half an ounce per 100 loose cubic yards had become workable at that gold price. The same report gave Yukon’s 2024 placer production as nearly 99,000 crude ounces, worth about C$284 million, the highest value on record there. Crude ounces are unrefined gold that still contains silver and other metals.

Chart

Gold price, quarterly average

US$ per troy ounce, nominal

Gold prices have moved a long way since. The World Bank Pink Sheet (October 2026) gives an average of US$3,442 per troy ounce for 2025 and US$4,319 for September 2026. Use the calculator below with today’s price, your own grade and the recovery you expect from your box.

Permits, safety and no mercury

Sluicing disturbs a stream bed, so most places regulate it. In Washington State, the Gold and Fish pamphlet (May 2021) serves as the permit for the hand methods it describes, but it does not cover suction dredges, motorized highbankers, power sluices or other motorized equipment, which need a separate written permit. It also does not replace landowner permission or other agency rules. Some public lands allow only a pan: at Whiskeytown National Recreation Area in California, the National Park Service limits panners to a metal or plastic pan and small hand tools and requires a one-dollar annual permit for anyone 17 or older.

Before you set up a box:

• Get permission. Do not work ground that someone else has staked, and ask the owner on private land.
• Check the state, provincial or national rules for your stream, including work windows that protect fish.
• Never use mercury. The Washington survey warns that mercury fumes are poisonous, and countries that signed the Minamata Convention, such as Kenya, have agreed to end mercury use in small-scale gold mining (BGS).
• Watch water levels and cold. Streams rise fast after rain or snowmelt.

Claim owners can read our step guides to California gold mining claims and gold claims in Alaska.

Choosing where to sluice

A sluice only recovers the gold that is in the gravel you feed it. Placer gold comes from eroded lode sources upstream, so the geology of the catchment decides what is possible. Our guide to types of gold deposits explains which host rocks shed gold into streams, and our Yukon gold mining and placer records page shows how one of the world’s best-known placer regions is mapped and claimed.

For consultants screening a large licence before anyone carries a box in, satellite imagery can narrow the search. Farmonaut’s satellite-based mineral detection maps alteration and drainage patterns across a licence area so that field crews can sample the most promising creeks first. Results are exploration targets, not resource estimates, and still need field sampling. To discuss a site, use the mining quote form or contact our team.

▶ How satellites help find gold: remote sensing explained. · 4:25

Frequently asked questions

What is sluicing for gold?

Sluicing is a placer mining method that washes gravel through a sloped trough with riffles. Gold and other heavy minerals settle behind the riffles while water carries lighter sand and stones out of the end.

What angle should a sluice box be set at?

The British Geological Survey says most sluice boxes run at about 10 to 15 degrees. It suggests 12 to 15 degrees for angle-iron riffles aimed at coarse gold and 7 to 12 degrees for expanded metal aimed at fine gold. Fine-tune by watching the sand between the riffles.

How much water does a sluice box need?

The Washington Geological Survey gives 7 to 13 times as much water as gravel for loose material. The BGS says water should make up about 85% to 95% of the slurry entering the box.

How often should you clean out a sluice box?

Clean up when black sand begins to pass over the second and third riffles of a short box, or when the gaps behind the riffles are packed and no longer moving. On rich gravel that can be often; on lean gravel it may be once a day.

Does a sluice box catch fine gold?

It catches some, but losses rise as particles get smaller. A BGS study in Kenya found recoveries as low as 20% for gold of 100 microns or finer. Longer boxes, finer matting, slower water and screened feed help.

What size screen should I use before sluicing?

The BGS screen table runs from 1 mm to 25 mm (1 inch), and the Washington survey reports grizzly openings of up to about 1 inch on larger boxes. Smaller, even feed is easier for the riffles to handle.

How do you swirl a gold pan properly?

Reduce the pan to concentrate first, then leave just enough water to cover it. Swirl slowly around the lower part of the pan so the water washes over the black sand. Light grains move further, and the gold stays behind as a tail.

Is a sluice box better than panning?

For moving gravel, yes. The Washington survey puts a pan at about 0.6 cubic yards a day for one person, against 10 to 15 cubic yards for two people on a sluice. Panning is still needed to test ground and to finish the concentrate.

Do I need a permit to use a sluice box?

Often, yes, and rules differ by place. Washington allows hand methods under its Gold and Fish pamphlet but needs a separate permit for motorized sluices. Some parks allow only a pan. Check with the land manager and the state or provincial regulator.

What is black sand in a sluice box?

Black sand is a mix of heavy dark minerals such as magnetite, ilmenite, chromite and garnet. It settles with gold because it is also dense, so seeing black sand in your riffles shows the box is trapping heavy minerals.