Gold Prospecting

Anyone who has ever found gold in a pan for the first time knows what "gold fever" is. It can't be described in words any easier than trying to explain what it's like to jump out of a perfectly good airplane and free fall. Both are exciting, though I can only guess about the latter.

I can tell you that, having found gold in a pan myself, it is VERY EXCITING! There are many naysayers out there that will tell you that "it's all been found" or "you can't do that". Anyone who tells you that, HAS NEVER BEEN PROSPECTING IN THEIR LIFE! I've been places where every shovel of dirt contains a quantity of gold, granted, not very much but hey, there's lots of dirt here.

Occasionally you will come across a "pay streak" that no one has ever worked before. They're hard to find, and I've never found one yet, but there are plenty of examples of people who have. One example happened in the 70's, on a river, not 100 yards from a major highway bridge, that thousands of people crossed every day. In one crack in the bedrock, 5 POUNDS of gold was found, 5 POUNDS!. Much more was found by this person, during the 3 months he worked this river. This was the 1970's, not the 1870's. There is still plenty out there.

For me, and many others, it's not just finding gold that lures us, but instead, the QUEST. Not knowing what you will find next, a sort of discovery process, with many a twist and turn. It's like being Sherlock Holms and Christopher Columbus, at the same time.

There are many tools used in prospecting, but the basic ones are the pan, shovel, 5 gal plastic bucket, and water. This is all you need to find gold. Everything else is to make it easier, faster, or more productive.

The first step is to learn something about prospecting. I will attempt to give you a little here, but there are much better sources for this information elsewhere.

Specific Gravity

This is the measure of the ratio of the weight of a given volume of something, to the same volume of water. In other words, water has a specific gravity of 1. Anything with a specific gravity less than 1 will float, anything greater than 1 will sink. Specific Gravity is just a way of expressing the "heaviness" of something.

Gold is a VERY heavy element. It has a specific gravity of around 19 (19 times heavier than water). Regular dirt, gravel, and rock, is somewhere between 2 and 3, roughly. A cubic foot of water weighs about 62 pounds. A cubic foot of gold weighs about 1200 pounds!

Gold is usually found with other heavier material, namely black sand. There are two versions of black sand. One is magnetic and called magnetite, and the other is non magnetic and called hematite. Both have a specific gravity of around 5. This black "sand" is roughly the consistency of regular beach sand or smaller, only it's twice as heavy and it's black.

Here are various elements and compounds and their respective specific gravity, starting at 1:

Water  1
Rocks  2.65
Diamond, Garnet, Ruby, Sapphire  3.5-4.3
Magnetite  5.1
Hematite   5.3
Silver 10-12
Lead  11.3
Mercury 13.5
Platinum 14-19
Gold 19.3

This is only a partial list, but includes the ones that you will probably find, when you're in the right place.

Every step in the prospecting process is directed toward separating the lighter rock and debris, from the black sand and heavier material. Black sand is twice as heavy as the rock, so what is usually done is to use the black sand as an indicator. If you're getting black sand, and keeping most of it, you are also keeping everything heavier. Black sand doesn't guarantee gold, but gold is ALWAYS found with black sand.

A pan, sluice, dredge, and high banker are all variations on the same theme. To pass water over some material, and carefully wash the lighter stuff away leaving the heavier stuff behind.

Five things affect this separating process. The slope of the surface the material is passing over, the volume of water, or flow, passing over the surface, the texture of the surface, the consistency of the material, and the shape of the gold.

Here's how these five "forces" break down. This is a little simplistic, but still useful.

Slope - Too steep, everything washes away.

Flow - Too much, everything washes away.

Texture - Too smooth, some good stuff may wash away, hence, riffles.

Consistency - Too wide a range of sizes of material, and everything washes away. The more consistent the material, the better. But it takes longer to get material more consistent, and you stand the chance of loosing some larger nuggets in the process. Generally, the best you can do is to limit the size of the material to the size of nugget you expect to find, and everything smaller.

Gold Shape - If the gold is primarily flakes, the difficulty in separating it from the rest increases dramatically. Flat gold tends to wash further down the sluice, than the equivalent weight in a more rounded shape.

Even though a rock might have a specific gravity of 2.7, and gold 19.3, a 5 pound rock is going to be harder to move than a 1 DWT (penny weight) gold nugget (an extreme case for discussion's sake). Another way of saying it, to get the 5 pound rocks to move, the angle and flow is going to have to be such that you won't keep so much as a speck of gold. It will all be washed away, before the 5 pound rocks!

Also, if the gold is flat flakes, they will tend to wash away even easier, before smaller rocks, and even black sand.

I like to use a 4 mesh (1/4 inch) screen, called a classifier, to eliminate all the larger stuff, and just work the smaller stuff. The best way to do this is to have two buckets with you, one with as much water as you're willing to carry. Place the classifier over the other bucket, and start putting material on the screen. Now slowly wet the material, to wash off any cemented material stuck to the larger stuff, into the bucket, discarding the larger stuff that won't go thru the screen. When you run out of water, dump it back out of the material bucket, and continue. You will loose water in the process, but if you're careful, you can fill the bucket with material this way, getting ALL the gold.

If you don't want to carry water, you can still use the classifier and also rub off as much cemented material as you can from the larger rocks. This way you will still get most of the gold, and hand carry the least amount of material.


Panning

Panning is the first skill you need to work on, to have much luck at finding a place to work. It is a very simple device, and looks just like it sounds, a pan, a foot across or larger and several inches deep. If you lined up 100 people, each with a pan, you would see demonstrated 100 different ways to pan. Everyone has their own twist but basically it's a two step process.

First you put some material into the pan and wash out as much of the lighter material as you can, leaving the heavier material in the pan. Then you move the black sand away from the gold and remove the gold.

The material you use for panning, can come from anywhere. One technique is to take a 5 gallon bucket and shovel, and dig the material from one location, and take it to the water to pan it out. You want to fill the pan with material, with all the larger stuff screened out

At first, the technique is to slowly, carefully, place the pan and it's contents, just under the surface of the water, hopefully in a quiet, slow moving pool, or tub. The idea here is to get the heavy stuff  to the bottom of the pan. The best way to do this is to get the material into a "liquid" state. The gold will drop, like a rock, to the bottom under these conditions.

To do this you have the material completely covered with water, then you agitate it. Slosh the material back and forth, side to side, front to back, or in a circle, tap with your fingers, or bump with your palm, but keep it "moving", for 10 seconds. By now, what gold is in the pan, is definitely on the bottom of the pan, period. This is called "stratifying" the material, sorting it out by specific gravity, the heaviest at the bottom, the lightest at the top.

Then you lift the pan just above the surface, emptying out some of the water, sloshing the material to keep it in a liquid state, with the pan tilted 30 degrees or so, and then quickly, slightly, tip the pan, allowing the water to flow over the material, washing the lighter material on top, over the edge and out of the pan. The angle you hold the pan, after you tip it, is the slope. Too steep, and too much washes away at once. Too shallow, and it takes all day to wash away the light stuff.

How much water, vs how much material is in the pan when you tip it over, is the flow. Too much water in the pan, and you wash away everything. So as you remove lighter material, you use less water each time, when you tip it, to maintain the correct flow. During all this you remove any larger pebbles, taking a good look at them before you throw them away.

Some pans have riffles built into them, along the edge of the pan. Riffles are indentations or ridges, that tend to trap heavy material. If you have this kind of pan, you have a better texture to work with, and better odds of keeping the gold. You should be tipping the pan in the direction of these riffles. The heaviest material will end up in these riffles.

You repeat this process of liquefying the material and tipping out the light stuff on top, until you have reduced the material to mostly black sand. If you are just looking around for a spot, and you don't care if you loose some small stuff, this can all happen pretty fast. You can reduce a pan of material to black sand in less than 5 minutes, when you get the hang of it, and keep most everything. What remains in the pan is called concentrates. It is concentrated material, mostly black sand, with most of the light stuff removed.

When you are down to the last few teaspoons of material, if there is any gold in the pan, you will see it soon. The process is a little different from here on. Now the object isn't to wash anything out of the pan, but to move the black sand away from the gold. It is still the same basic process, wash away the lighter stuff, leaving the heavier behind.

You want about a 1/4 inch of water in the pan, or less. Any little rocks should be removed (check them out). Tilt the pan, sloshing it, tapping it, working the material into the corner of the pan, until it's all there. Then level the pan and agitate just a little to "flatten out" the material a little, still keeping it together.

Now you start a circular motion causing the water to move around in circles in the pan, slowly washing the black sand away from the gold. This part takes considerable patience. The black sand is heavy so it is a slower process moving it. Gold is 4 times heavier than black sand, so it tends to sit still, while the black sand moves, if you have the right technique.

What slows down the process is that the black sand, from a consistency point of view, is, in many cases, much more coarse than the fine gold, so you are fighting the problem of the 5 lb rock and the penny weight nugget.

There is a necessary accessory to the pan, called the sucker bottle. It is just an ordinary plastic container, with a tube extending out one end. You squeeze the bottle, and then place the tip over the gold and release your squeeze on the bottle, allowing it to "suck" up gold from the pan.

Once the gold is by itself, level the pan and use the sucker bottle to remove the gold.

With a little practice, you'll have this down pat.

Sluice Box

A sluice box is a long tray, open at both ends, that has riffles, spaced the whole length, every few inches, crossways to the length of the tray. This causes barriers to the water flow, that creates eddies, giving the heavier material a chance to drop to the bottom, behind the riffles. The "upstream" end of the sluice usually has a flare, to catch and funnel more water thru.

The sluice is usually placed in the running water, held in place by larger rocks, packed in against the sides. The slope of the sluice can be adjusted somewhat, by arranging rocks under the sluice. Also the flow of water can be adjusted by placing a large rock, in front of the intake to the sluice, diverting some of the water around the sluice. You have to play with these variables, until you get the material moving, leaving the black sand in the riffles.

When you're ready, you start dropping in material at the upstream end of the sluice. As material piles up at the downstream end, you will have to keep it moved out, or move the sluice slowly upstream, as you work the material.

What usually happens is that when operation first starts with a sluice, the riffles fill up with lighter material, because there's more of it But if you watch it closely, this lighter material will slowly migrate down stream and finally out the end of the sluice, washing out from behind one riffle, and then the next. But during the flow, as heavier stuff comes through, it also settles behind the riffles, and as lighter material migrates, the heavier stuff settles, slowly to the bottom, assuming you have the slope and flow correct.

Eventually the riffles fill up with heavy material. When you see lots of black sand showing in the riffles, you could be in a good spot.

The reason that riffles work is two fold. First, there is an eddy created behind each riffle, causing a temporary lull in the flow. The material that is flowing is in somewhat of a liquid state, that causes the heavies to be at the very bottom of the flow. As the flow passes over a riffle, the heavies fall to the bottom in behind a riffle.

Second, the riffles are spaced a couple of inches apart, and create a series of dams, stopping the creep of the heavy material down the sluice. Without them, there would be a slow, but sure flow (creep) of gold out the end of the sluice.

Normally most of the trapped gold will be behind the first couple of riffles. This is due to the fact that the material is in a liquid state, and the heavies fall fast, landing in the first few riffles. Smaller flour gold may extend several riffles further, and, hopefully, the last few riffles have NO gold, otherwise, you're loosing some.

The riffles are usually hinged at the upstream end, with a latch at the downstream end. So you can release the latch, and swing the riffles up. Usually there will be a 3/16th inch layer of material called miner's moss, that resembles in texture, a kitchen scouring pad, laying on the surface of the sluice. It is a loose weave matt with lots of air space. It traps and holds the smallest gold particles. On top of that can be a layer of expanded metal. This creates a criss-cross pattern of spaces, each with their own eddies. Then the riffles, that resemble a ladder, with each riffle a rung, when swung up, is lowered into place and latched down.

Each time you clean up, you raise the riffles, and remove the moss. You then wash down the sluice, wash out the moss, and put it back together, all inside a tub, of course. How often you do this depends on whether you want to know what you're getting, whether to move or not. Otherwise, you can probably run the sluice for quite a while, before cleaning (I used to think that you should clean it often, but I tend to think otherwise now). The gold is going to fall out early in it's travels down the sluice, and it would have to fill up with gold, before you started loosing anything.

The way to tell if you have things close to right or not, is to notice whether you are finding gold many riffles down from the front of the sluice. It should be very close to the front, in the first 1/2 of the sluice for sure. One way to always know is to make the miners moss two sections, butted together. All the gold should be in the first mat. There should be nearly nothing in the second. I have divided mine into 4 sections. I pan the last section to make sure that there is nothing in it. I pan the first section to see what I'm getting.
 

Dredge

A dredge is a floating sluice with a few things added. There is a gasoline engine coupled to a high volume water pump. There is also a large hose and nozzle attached to the upstream end of the sluice. The nozzle is essentially a straight piece of pipe, that has been bent 30 degrees or so, in the middle. At the point the pipe bends, another piece of smaller pipe, shaped like a U, is welded in so that one end of the U is fastened here and the other is pointing the same direction as the output end of the nozzle.

A hose, the diameter of the nozzle, called the suction hose, and the pump hose, are fastened to the nozzle and run together, back to the dredge. The small hose connects to the pump. The large hose is connected to the upstream end of the sluice. The pump has a short hose, with a screened opening, that is submerged, that is the water intake to the pump, and is called a foot. The water from the pump flows down the small hose to the nozzle, where it is forced into the large hose, creating a suction at the end of the nozzle.

This suction force is considerable, and something large, sucked up to the nozzle, is hard to get loose. The suction draws in anything that will fit into the nozzle opening. This material is forced thru the large hose until it is dumped out on the sluice. The rest is history. The slope is adjusted, along with the speed of the pump motor to control flow. The nozzle acts as a classifier, to eliminate anything larger than the size of the nozzle.

So you move along, probing between large rocks, sucking up the smaller debris. You will spend some time moving larger rocks out of the way so you can get deeper. Generally you move upstream as you go, taking in material upstream, and dumping material downstream.

Dredges are measured by the size of the nozzle opening. They range from 2 inches, on up to larger than 8. The regulations vary, in some cases, with the size. The larger the size, the more difficult it is to find a place to use it. The larger the dredge, the more water you need, but the more material you move. The amount of gold you can get in any given amount of time is a direct relation to how much material you can move. The more material, the more gold.

Operating a dredge is really a job requiring more than one person. While one person is handling the nozzle, another is needed to keep the suction hose flowing, and remove the larger rocks from the sluice. As material moves up the suction hose, rocks become jammed, causing the flow thru the hose to stop. Tapping the hose with a large screwdriver shaft does a pretty good job of loosening the jam, without damaging the plastic hose. Also, where the suction hose dumps out into the sluice, there is usually a heavy flap, that lays over this entry point, that spreads the flow out over the entire width of the sluice, creating a more even flow through the sluice. There is also a hole, that allows you to insert the large screw driver in, to un-jam the last foot of the suction hose.

Rocks tend to pile up here also, and it needs constant attention to keep it clear. The suction hose will get jammed every minute or so. When you work a dredge by yourself, you have to stop working material to do these other jobs. It can be done, though, and there's no split at the end.

High Banker

A high banker is basically a dredge, taken out of the water and moved to a point, some distance from water, normally above the regular bank, on a higher bank or bench. The pump is taken off and placed next to the water, and the foot placed in a good spot, under water. A long water hose is attached to the pump to reach the high banker. The suction hose is discarded. Instead, the upstream end of the sluice has a hopper, where material is shoveled or dumped in. The water hose feeds into here also, and supplies the water flow to move the material over the sluice. The hopper has a grate, called a grizzly, that classifies the material, and rejects larger rocks, allowing them to slide off to the side.

The slope is adjusted by telescopic legs on the high banker. The flow is adjusted with the engine throttle.

Hooka Rigg

Hooka is a system consisting of a compressor, air hoses, and breathing regulator, that allow you to go beneath the surface of the water and worked submerged for extended periods with a dredge. It is somewhat like SCUBA, but you don't need tanks, as the compressor furnishes a steady supply of air. You can go as deep as 40 feet, though I'm not sure that I would ever work that deep. There is always a danger of becomming trapped under the water because a boulder rolled onto an arm or leg. You must excercise extreme caution when using this method. Two people is an absolute requirement, for safety sake.

Using the hooka rigg, your take home gold will definitely increase, because you can work as deep as you want, getting to places where no one has worked as much.


Finding a Place

The next step in prospecting is to find a place to do it, not just any place, but a place where you stand a chance of finding gold. I belong to GPAA (Gold Prospectors Association of America) and LDMA (Lost Dutchmans Mining Association). Both of these organizations have thousands of acres of rivers and streams, that have produced gold in the past, and still do. These claims range from the east coast to the west, and from Canada to Mexico. Nearly everyone lives within a few hundred miles of one of these claims. As a member, you get to keep all the gold you find.

There are also public areas all across the country, set up exclusively for recreational panning, at little or no cost, available to anyone. Again you get to keep everything you find.

If all you are going to do is pan, there is usually no permits or paperwork to file before prospecting, though each state is different and you should always check with a ranger or the BLM, or the owner, before you go prospecting. In the case of the GPAA and LDMA claims, a dredging permit is required, in some cases, depending on the size of the dredge, and the state you're in. Also there are seasons for dredging in many streams and rivers, to respect the spawning seasons of several varieties of fish.

Locating the right spot

Even a stream can be looked at as a natural sluice, and follows the same rules, as far as gold and lighter material. The stream is flowing at an angle or slope, the water is flowing at some rate, material is flowing, the stream bed is strewn with large boulders, acting as riffles. These are the places you want to look for gold. Or at the end of a rapids, where the water slows, and the bed levels out some. Also, any exposed bedrock, no matter how high up, is always a good prospect.

Most rules restrict dredging to within the normal high water stream or river bed. Digging out the normal bank is prohibited. But there are sometimes ancient stream banks, or benches, located well above the normal bank. You can usually shovel this material into buckets and transport it to the water to work, or, if permitted, use a high banker.

In respect of the right to prospect, you should always fill in any holes you dig. You usually won't remove that much material, because a large part of it will be large rocks and boulders. You will be taking the material between the rocks. You can then move the rocks back in.

In my humble opinion, there are thousands of places where you can get an ounce of gold a day, with a small dredge, for as many days as you can work.

My most recent prospecting trip

 I just returned from a two week trip to Colorado, where I used my dredge on the Arkansas River, just north of Buena Vista. I must admit defeat though. My brother and I worked 10 days at hard labor, and only returned with a little over a quarter of an ounce! It was dissapointing as to the amount of gold we got, but it was a truely beautiful place, and we had a terrific time. As I've said earlier, it's not how much gold you find, but the search, that keeps me going. We found some pickers (small pieces of gold that you can actually pick up out of the pan with your fingers) but the water level was too high to work the good places, where I'm sure we would have done much better.

We were there between July 17 and July 30, 1998. A better time would have been the first two weeks of September, when the river is at it's lowest level, just before the cold sets in. It rained nearly every day, which raised the water level of the river too high for the way we came prepaired to work.

The gold here is mostly very small flakes, with some larger flakes and small nuggets. Separating the small flake gold from the rest of the material proved to be quite a task. I used my spiral panner to extract the black sand form the dredge concentrates in Colorado, which worked quite well. I brought home a little over a half a gallon of pure black sand concentrates. I waited until I returned home to seperate the gold from the black sand.

I had a micro sluice, that I had intended to use at home to separate the gold from the black sand, but I ended up putting one tablespoon of black sand in a pan and then panning the black sand away from the gold and using a sucker bottle to get the gold out of the pan. It was a long process, with meager results.

The small flakes of gold tend to move around before the black sand, making it difficult to move the black sand away from the gold. It took great care, and good panning skills to perform the task. There is still some gold in the black sand that I gave up on, and will probably use some mercury to amalgamate the gold to get the last of it out.

Mercury is not a fun thing to work with, and should only be used when the gold is just too small to pan out. I also have a retort, that is sort of a still, that you heat the amalgum to boil off the mercury. If used properly, there shouldn't be any problems. But it should be done with great care and with good ventilation as mercury vapor is very toxic, and should never be breathed by anyone.

The retort has a coil that can be surrounded with ice water, to aid in the condensing of the mercury vapor, so that liquid mercury comes out the other end. The gold is left in the heating chamber, as the mercury boils off at a much lower temperature than the melting point of gold.

The amalgum is placed in the heating chamber and the mercury is boiled off and condenses back into liquid mercury, which is relatively safe to handle. There are instructions that come with the retort, that should be read carefully, so that you operate it in a safe manner. I am not advocating the use of a retort, just mentioning it here as one method of removing fine gold from black sand concentrates.

I will be adding a wet suite and maybe hooka gear to my next trip. The chest waders I had, limited how deep we could get with the dredge nozzle, as deep as we could reach with our arms, and not let water into the chest waders.

Kenneth Richardson


Here are a few useful links

The Mineral Gallery
TreasureNet
GOLDSHEET
 
 

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