Sluice Box

How to sluice for gold

So you want to learn how to sluice for gold?  First we’ll assume that you know where to find gold because you’ve already prospected out a site by gold panning.  You’ve hit a good strike and now it’s time to step up your game because you know that a pan just isn’t going to cut it anymore.  The next step for you is to purchase or build a sluice box.

How to Choose the Right Sluice Box:

There are many types of sluices, but they all rely on the same concept that as gold panning:  heavier materials are separated by gravity when they are put into suspension.  The basic idea is that water and gravels will be fed through a sluice and the heavier materials (i.e. GOLD) will become trapped while the lighter materials will wash away.  For the hobby prospector, there are three basic types of sluices:  riffle sluices, drop sluices, and combination sluices.

Riffle sluices are long boxes with both ends open and crossed by various obstacles or “riffles” that water must go over.  As the water crosses to the downstream side of the riffle the area immediately behind the obstacle becomes a low pressure zone.  Any heavy materials passing over the riffle will get caught in this area of low pressure.

Drop sluices are also long boxes with both ends open, but instead of having obstacles for the water to flow over, they allow a free flow of water over small slats or holes in the floor of the box.  The idea with this set up is that as the water carries materials through the box, the heavier materials will “drop” into the cracks and crevices of the sluice’s floor and get stuck.  Crevicing for gold in bedrock utilizes this same idea.  Combination sluices are, of course, a combination of a riffled sluice and a drop sluice.

The choice of sluice can be made based on several factors including water flow, walking distance to your strike, cost, weight, and many others.  The most important factor, however, is personal preference. 

Remember: No sluice will recover 100% of the gold that passes through it.    I personally prefer a mini sluice with Hungarian riffles because it works well in the low flowing creeks that I prospect and it’s small and light enough to fit into a backpack.  There are lots of choices out there and some will work better than others.  I recommend experimenting until you find one that’s right for you and your prospecting circumstances.

How to Set Up Your Sluice Box:

Once you’ve got your sluice to your prospecting area it’s time to set it up.  Setting up your sluice box is the most critical part of the operation.  You could have the best sluice in the world, but if set up incorrectly it will just dump your gold back right back into the creek.  There is a single basic rule for sluicing.  It states that for every foot of sluice, you should have a drop of one inch.  Therefore a 24 inch sluice will have a 2 inch drop between the head of the box and the end of the sluice.  This comes to about an 8% grade.  Now this all depends on water flow.  If you have a stream with rushing water, you might have to lessen your grade to ensure the material will slow down as it crosses your sluices trapping devices.  If you have a slow flowing creek*, you might have to raise the grade to make sure that material is washing through your sluice fast enough.  Experiment with your sluice as you set it up by tossing handfuls of sand or small gravels into it until the flow looks “right”.  Experience will be the best teacher here.

*I prospect many low flow streams.  If there isn’t enough flow to fill your sluice, you might try damming the water.  This will accomplish two things:  It will ensure that you can utilize all of the water flowing through the stream and will allow you to adjust your grade because you’ll be using the sluice as the dam’s “spillway”.  The higher the dam, the higher your grade will be.

The Proper Way to Opperate a Sluice Box:

Now that you’re all set up, it’s time to start using your sluice to recover some gold!  What you’ll want to do is first classify your materials.  This can be done by running streambed gravels through a ½ inch screen or mesh.  You want to make sure that all of the rocks larger than ½ inch are removed and not fed through your sluice.  Large rocks tend to change the low pressure zones in your sluice box and can cause gold that was trapped to be freed and wash out.  Before you dump these larger gravels be sure to check them for large nuggets!

Once you have a quantity of classified material slowly start feeding your sluice.  You want to go slow enough so that the last bit of material you put into the head of your sluice has time to wash away before you put in the next scoop.  This will ensure that your riffles or drops are not clogged and working property.  If all goes well, you should start seeing small flecks of gold appearing at the head of your sluice.

How to Clean Up Your Sluice Box:

Now for the fun part: recovery!  After you’ve run your sluice for a while it’ll be time to clean it out.  Many sluices for sale have removable riffles that allow easy clean up.  If not, you’ll want to place your sluice over a bucket or other container and, using a gold pan, wash out all of the materials that have been trapped in the low pressure zones.  Take this material and set it aside.  You’ll want to process it at home using a gold pan when you have plenty of time to be thorough.  Remember, the more material you process in the field, the more gold you’ll be taking home.  Don’t be in too much of a hurry to fully separate your gold until you’re out of the field and in a setting where you can process this pay dirt with the care that it deserves!

Now you know the basics of how to sluice for gold.  Get out there and give it a try.  You’ll recover more gold than simple panning and have a great time doing it.

Sluicing for gold
Compact 24" Mini Sluice Box
Amazon Price: $67.74 Buy Now
(price as of Oct 13, 2015)
The author recommends a mini sluice with Hungarian riffles if you're looking for a good sluice to start out with. This sluice works low flow creeks and it's small and light enough to fit into a backpack. If you decide to move up to a larger sluice in the future, the mini sluice is also great for processing concentrates.