You want to find gold? Is that right? But you don’t know where to start? Actually, looking for gold is not that difficult, because the gold deposit is quite predictable. But you still need to know a few rules. I must also warn you that finding gold flakes or nuggets will require a bit of diligence and research, because finding gold is well deserved. The precious metal remains rare, but the day you find it, you will be able to boast of having understood how a gold prospector do.
The means used can be consequent with a non-negligible ecological cost. Fortunately, in spite of its rarity, the gold miner can extract it without too many administrative constraints in order to be in accordance with the legislation, (at least for the moment) in a leisure environment. For those who embark on the adventure of gold panning, the first question that comes to mind is “where does it come from, where can I find it, how can I look for it? ». The goal is to provide you with the right gold panning technics.
Gold, where are you?
- Atomic number : 79.
- Symbol : Au.
- Density : ~19,3 g·cm-3.
This is the question we will try to answer in a very theoretical way. For this, we will rely on physical principles, on simplified images. Sometimes theory does not apply as it should; only experience in the field pays.
The origins of gold, the search:
For an recreational gold panner, the simplest way is to search in a gold bearing stream. Usually near mountainous massifs. Also, the distribution of gold-bearing rivers and streams is rather uneven. Some are found in the Pyrenees, the Jura massif, the Alps and the Massif Central. There are also auriferous zones in plains like Brittany to name but a few.
But they can also be found in areas that only insiders know about. For example some beaches in Brittany and Gironde. To say that 90% of French rivers are auriferous is a lie, except if we consider that a river is auriferous when it has at least 1 straw . On the other hand, it is well estimated that less than 2% of rivers contain 1 straw per beat (on average). Everything is thus a question of proportion. Also, it is easy to say that gold repair is uneven.
The genesis of gold :
Through erosion, water pulls various materials from the earth, including this precious metal that is inexorably found in the watercourse. The activity of the floods makes it possible to move all the materials, but before that, this gold does come from somewhere? Originally, gold is formed at the birth of mountains. The movements of the tectonic plates during the genesis of our planet caused an immense amount of friction and pressure releasing a lot of energy.
The gold has risen as vapors with the heavy minerals (carbon) and crystallized in the veins and fissures of the geological rock. Very often gold is found in association with another mineral, quartz, which acts as a substrate, filling the fissures or faults of certain rock formations. This is why they are often referred to as gold-bearing quartz veins.
As mentioned above, erosion exposes some deposits. The mother rock is then attacked by the mechanical action of the water in the rivers, which finishes the work of disintegrating the rock, releasing the gold in the form of dots, flakes, grains and nuggets of gold. With the floods, he and the other materials will move from the mountain to the lower rivers.
Gold also moves as ions dissolved in acidic waters can precipitate on contact with basic rocks such as shale. This last form is still being studied today.
Now, where are you? Now, what are you doing ?
If you look at the beginning of the article on the chemical characteristics of gold, its density is highlighted. ~19.3 g-cm3. Since we are only talking about physical characteristics, we consider that density = density. We will therefore linger on the characteristics of the weight of a particle evolving in a moving aquatic environment because this is the key to the problem.
First of all, let’s start with a little reminder of a physical principle that will interest us. Archimedes’ thrust.
It also applies when moving water drags an object with it. The displacement of this object will depend on the initial speed of the thrust (here, it will be the current), the volume of the object and its weight. Without obstacle, the object moves, more or less quickly, depending on its weight and volume.
Gold, a heavy metal :
In our rivers, gold is the heaviest metal. Therefore, both the prospecting and the actual extraction are always based on the fact that gold is the heaviest material. Gold follows the current along a certain path called “the gold line” and will sometimes get trapped. This gold line has a certain peculiarity. It is made up of equally heavy materials (ferrites, magnetites, red blood cells, gold and any other debris of ferrous origin). All these sets move very slowly according to certain configurations of the terrain. These materials are trapped by various natural obstacles.
This is precisely what we will see later on. Current plays a crucial role in this equation. It is based on a physical principle that everyone knows: Archimedes’ push. Not that gold floats. Rather, we will focus on the displacement of heavy sands in relation to the rest of the alluvium.
The different configurations to find gold deposits :
The gold movement :
As gold does not float, what will interest us is above all the displacement of the heavy sands in relation to the rest of the alluvium. Finally, gold panning is nothing more than an exercise in physics that uses several well-known principles. The goal of the gold panner will therefore be to understand the behavior of the river’s course in order to determine the places where the gold could have been trapped and extracted. This is called “reading the soul of the river”.
NB: All these explanations are only theoretical. It happens that the reality in the field is quite different. It is also the magic of gold panning. In reality, it is not magic, it is experience.
The gold line (the shortest way) :
If you talk to a gold panning, you will hear the word “gold line” from his mouth. It is nothing more than the path the gold takes through the current. Its high density (and therefore its weight) means that it will follow a very specific path. Generally speaking, gold will follow the shortest path. A greater flow, such as during a flood, can modify this path significantly depending on the configuration of the bedrock.
These floods carry gold as well as gravel and pebbles. When the flood subsides, all moving objects are deposited in specific areas. These zones are areas of low pressure, an abrupt slowing of the current. The gold, being heavier, will tend to be deposited first on these zones of lull. It is precisely the study of these zones that will allow the gold prospector to find “The spot”.
NB: Fortunately, gold does not move by itself. There are also other dense materials (less than gold) that allow to spot it (black sand, garnets). Black sand (because this is what we most often come across) is a sand that is loaded with ferrous minerals such as magnetite or hematite. Some garbage can also accompany the gold such as rusty iron or lead for fishing. The presence of these elements is often a sign that you are likely to find gold in this area.
The different configurations favouring gold deposits :
The meanders :
The first area generating a drop in current pressure is the meander, and more broadly a curve.
In a meander, there is a deposit of pebbles that forms on the inner part. In a gold-bearing river, gold deposits are made on these gravel banks. These placers gold, as they are called, are made of pebbles, sediments or all sedimentary rocks, clays. Gold and pebbles being heavy, they seek to be deposited where the current is slowest. This is particularly true during flood periods. It is thus on the bank on the inner side that the deposit will be made.
There is the current that we see but there is also what happens at the bottom of the water. If the gold line follows the inner part of the curve, it is also because of a side current. This swirling current goes from the outer bank (erosion zone) to the inner bank (deposition zone).
Floods can be beneficial :
In times of flood, these currents are faster and more powerful. The gold line will therefore change its path. With a faster current, the outer bank will erode, feeding the inside of the plain with rock and even gold. Generally, it is at the front of the placer gold deposits that one will find the greatest concentration of gold and large pebbles. Conversely, the lighter sands will be deposited at the end, often sterile. It is a phenomenon of settling by gravity.
NB: During floods, the increase in flow and currents considerably accentuates the movement of materials.
The rock :
Rocks are also very good gold traps, as long as they are in contact with the current. This obstacle will create turbulence in its wake. This turbulence will disturb the speed of the current causing a zone of low pressure and the current will suddenly decrease. The turbulence plays a role in sorting, retaining the heaviest materials just behind the obstacle and releasing the lightest ones. As before, the variation of the flow rate influences the power of the currents, and thus the obstacle’s ability to capture the gold. Obstacles along the river bank :
Banks with obstacles :
Another very frequent case is a rock, a torn tree trunk or any other obstacle located on the shore and overflowing into the water will have the same effect as before. Always on the same principle, the obstacle is opposed to the current. It modifies part of the trajectory of the initial current by generating behind it a whirlpool and slowing down the speed of the water in this area.
The deposition capacity is even more important here because the bank amplifies the effect and thus accentuates the accumulation of heavy materials. It is interesting to note that if the obstacle presents irregularities on its surface, it will be all the more traps for the gold to be prospected.
Irregular banks :
It is rare to find perfectly parallel banks in the natural environment. In this case, we have a bank that presents a narrowing of the watercourse and then a widening. In fluid mechanics, we call this the “VENTURI effect”. To put it simply, this narrowing causes the current to accelerate and the subsequent widening, creating a sudden slowing down and therefore a drop in pressure, which is called “heavy material deposition”, i.e. gold. In this type of configuration, it is necessary to work in an aquatic environment to recover the gravel, knowing that the prospecting and extraction zone can be very vast.
The zones of confluence :
A confluence is where one stream flows into another. Under conditions where the main stream keeps a straight path, the arrival of another stream across will impact the path of the gold line. At this crossing, the current of the adjacent arm comes into contact with the current of the main arm, which is much stronger. This will have the effect of diverting all the material carried towards the opposite bank and the gold line. The origin of the gold (main and/or adjacent arm) will have no impact on the deposit.
We have just seen the main conditions of gold deposition but it is also interesting to see what happens on the bedrock and underwater. The bed of the stream is far from being smooth and perfectly flat. And it is on this irregular surface of the bed that the gold line flows. It is therefore on the bedrock (bedrock or bedrock substrate) that the gold prospecting must work in priority because it is a surface that remains stable despite the current, unlike gravel and pebbles. Fortunately, there are certain particular predispositions that make it possible to trap gold.
In profile, what does it look like?
The immersed rock or pebble :
In the water, the most common obstacles to explore are rocks or large pebbles. In fact, this is not what is missing… The ideal, above all, is to ask yourself the question. In case of flood, will it be washed away or not? If it is likely to stay in place, there will be a good chance of finding gold. It should also be noted that irregular shapes of bedrock with this configuration will unfortunately have the same effect. This kind of obstacle has a very particular effect on the current.
In opposition, it diverts the current all around it and generates in its wake a vortex. As seen previously, this vortex will capture the materials carried by the current and will sort them. Only the heaviest particles will remain in contact with the rock, sheltered from the tumult of the vortex and the rest will be ejected.
Collapse of the bed rock :
In some places, you will notice that the bedrock is getting deeper. The volume of water becomes larger and the speed of the current decreases. This slowing down is a factor favouring the deposition of materials. The rollers stabilize in this depression zone and in turn act as obstacles. It will then be interesting to look for gold bearing gravels behind or under the larger pebbles. The objective for the gold panner will be to reach the bedrock under the pebbles. When the bedrock floor rises, there is an erosion phenomenon on this part that can also capture gold and heavy sands.
The pots :
The cauldron is the name given, in the world of gold panning, to describe a hole in the bedrock or in a submerged rock. This hole causes a vacuum which, with the speed of the current, will create a vortex. As always, this vortex will capture and sort the materials. These pots are very sought after by the gold miners because they know they will find gold and sometimes in large quantities. However, it can sometimes be difficult to locate because it happens that the basin is completely clogged and appears invisible. When mining a basin, the most interesting part is at the bottom, because the concentration of gold and heavy sand is often higher than elsewhere.
Pots are natural holes in the bedrock. Ideal place to prospect if you don’t have a gravel bank within reach of a shovel.
You just have to make sure that at some point in the year the hole is under water so that it fills up with gravel. Underwater and under the effect of the current, the inside of the hole remains sheltered from the tumult of the water. It is said to be a low-pressure zone or calm zone that favors deposits. This hole will still be swept by the current but with much less intensity. The deposits in this area are stirred up. The materials are sorted out. The heaviest remain at the bottom. The lighter ones leave the hole and continue their way.
During your prospecting, you may find them out of the water but generally they are submerged. When you prospect a pot, it is often filled with water. First, start with your shovel, then if there is too much water finish with the hand pump. The highest concentration of gold is found at the deepest point, in contact with the rock. When you work on a pot, it must be completely emptied.
Faults and cracks :
If the bedrock generally looks smooth and slippery, its very structure is not. Bedrock can be compared to slabs laid next to each other. Some bedrock “slabs” may also show even minute cracks. All these spaces are called faults or cracks. Of varying depths and shapes, it is a very interesting ground to scratch.
Faults have the same effect as a pot but on a much smaller scale. Curiously it is often in the faults that we find the biggest flakes (see nuggets). However, the extraction is often difficult because the pebbles tend to get stuck in the faults; specific material (hook) is then necessary. But as always, perseverance pays!
Just keep in mind that the current is the energy that allows any form of gold deposit. This deposit is made either by the creation of a vortex due to an obstacle, or by a slowing down of the current itself which creates a phenomenon of decantation of the materials under the effect of gravity. What differentiates a good gold prospector from a bad one is his ability to decipher these phenomena in the natural environment. But nature has many surprises in store for us. Experience shows us that the theory can be challenged in some cases!
The faults can be on the surface when the level is low. They are more numerous in the river bed.
Faults are large cracks in the rock. They work on the same principle as a pot. They can be in the longitudinal or transverse direction of the current. The goal for you will be to completely extract everything you can find in them. Even if it is prospecting, you will not have wasted your time. It is very likely that some pebbles will be stuck and the sands compacted. Do not hesitate to use a blunt object to dislodge them. The more difficult it is to extract, the older and more compacted the area is.
The cracks are faults but small in size (about 1 cm maximum). They can be found on a rock or bedrock. It is not because it is smaller that there is no gold. For the cracks, 2 tools will be necessary. In case the rock is submerged, use a hand pump or a suction bottle. If it is on the surface, use a hook or other blunt tool.
NB: you may be lucky to find all these configurations of areas at the water’s edge but make no mistake, it is essentially in the water that you will find this kind of trap. That’s why, for prospecting (and the rest), a hand pump is indispensable; it is in the water that the best deposits are found.
How do you apply all this to find gold in the field ?
The history of the river :
There is no mystery. If the stream in question contains gold, chances are it has been mined in the past. For this, Google is our friend, as well as some books that are still rare to find. It happens however to find streams that have escaped a past exploitation and therefore not listed.
To say that 80% of the rivers are auriferous is a crude lie, because gold does exist, sometimes even in greater concentrations than in the Klondike. However, the geographical areas that can really be mined are poorly represented and very localized on ancient Quaternary massifs from Brittany to the Pyrenees, passing through the Massif Central from East to West.
Water heights :
Check the average minimum and maximum height of the watercourse to be prospected. Indeed, gold panning remains a seasonal activity, often practiced in the summer, when the watercourses are at their lowest. For a gold prospector, it will be interesting to know the maximum height of water (vigicrues).
There is a maximum height which is generally during the melting of the ice in spring, taking into account the accumulation of precipitation. It is best to follow the water height during a flood, especially if it occurs before the start of your gold panning session.
The two reasons that favour research are,: The first is the height of the flood. It will allow you to search more areas in relation to the height of the banks. During floods, even heavy materials are stirred on the surface, contrary to what some people may believe and say here and there.
The second reason is that a current will not necessarily take the same path (bed) as when the river is at a low level. The gold line may deviate from its usual path. Therefore, it is recommended to go and see the behavior of the river during these flood periods to visualize these phenomena. This will give you indications when you prospect when the levels are at their lowest.
What equipment should I use to prospect for gold?
Technically, you don’t need much, but the little you take will be indispensable. The first indispensable thing to have is an gold pan a batea, a shovel, even in a miniature version, a small hook with cracks, a suction cup to recover the precious metal and a hand pump to suck gravel from the water. That’s it!! Leave your ramp at home because it’s the best way to waste time.
Why a hand pump? And why isn’t the sieve in this list? Two very relevant questions.
A hand pump should be as important to you as a mantle.
During some introductory courses, this tool is almost never used, yet it remains indispensable. Indeed, even if gold is deposited on banks and gravel banks out of the water, their quantities and qualities are much more important in the water on the bedrock. The hand pump remains a simple tool to make yourself for a very affordable price. You will have noticed that I am not talking about sieves and the reason is very simple: In prospecting, the goal is to determine where the deposit is the most important.
To prospect properly, it is necessary to test and sample :
When taking samples, it is preferable to test raw gravel with the same volume of gravel to be tested in the pan. Thus, with an equivalent volume of gravel, you will have a perfect point of comparison on your different samples. In prospecting, it is necessary to travel light because you will certainly have to travel a long way. It is useless to load yourself too much. You should also bring a pair of waders so that you can walk in the water without being afraid of getting wet.
What are the first things to look at before you start prospecting?
That’s it, you have found the ideal river, the right time to go there, and a very precise area where to spend your (1/2) day! Here you are on the spot and in front of you, a whole play area. The big question then arises: “where to start? »
Learn to read the river :
The first thing you’re going to have to feel is the soul of the river. How it behaves in front of your eyes, and imagining in parallel, how it behaved during a flood. At this moment, you have already gathered quite a lot of information, even if it is the first time you come to this place. The first data you will look for will be on your phone (or your pc before you leave).
A small tour on vigicrue to raise the current water level. This way you can imagine how high the water has risen to its highest point. This data is very important. It allows you to visualize areas that were under water a few months ago and are dry now.
How to do it?
The very first thing to look at is obviously the current. It’s the gold carrier. We look at how it flows: if there are zones of acceleration or deceleration, zones where there is a lot or little bottom, if the water flows in a laminar or eddy way, if the current meanders or stays straight, if there are big rocks visible on the surface.
One must always keep in mind that the gold line, and therefore the gold, will tend to get trapped when the water slows down, or when encountering an obstacle, and imagine how the water will behave when the level is much higher in relation to all this.
Look at the pebbles :
The easiest way to start is to observe the gravel banks. Take a closer look at the pebbles, sands and more generally the minerals. If possible, prefer natural traps such as faults, holes, large rocks and, as a last resort, large pebbles. It is interesting to look for the presence of some minerals such as quartz, hematite and even small pieces of iron or fishing sinkers (probable indicator of gold deposit).
The presence of quartz will comfort you in the presence of gold because one does not go without the other. As a reminder, it is in quartz that the native gold is trapped in the rock before being found in the river. Hematite and ferrite are constituents of the black sand accompanying the gold. Finally, the small pieces of iron and lead are very good indicators of a possible gold deposit because of their weight, quite important, close to that of gold. In some rivers like the Ariège or the Limousin, garnets (heavy) are much more present than hematite.
Visualize and imagine the repositories :
Also, it will be necessary to adapt according to the prospecting area. It is interesting to visualize, on the bank or a gravel bank, the presence of vegetation (small grasses). This gives you the maximum limit of the water level. It is the same for tree trunks gathered on the same area. A zone of vegetation starts the creation of overburden.
The additional advantage in this case is that you have the additional information that at this point the current slows down. When the current slows down, the gold is deposited. Another point to look at is the size of the grains deposited. A pebble being heavier than a grain of sand, you will have a better chance of finding gold of a large size. If you find a sand deposit in an area, it will usually be sterile. Indeed, a gravel bank acts as a gravity settling tank.
Watch the Vigicrue information in time :
With a higher water level, this bench will trap the heavier particles and let the lighter ones through. Thus the large and dense pebbles will be superimposed and feed the construction of the bench with the gold inside. The sands will on the contrary continue their way and accumulate where the current is less strong at the end of the bench.
NB: In this precise moment of observation of the area, all this information allows you to draw a diagram of the river. You begin to study the “soul of the river”. This is probably the most important moment, because by drawing up this diagram, you will be able to prioritize certain areas rather than others. As you prospect, you will gradually understand where the gold is (or is not) deposited and the different mechanisms of the deposits.
A river has a soul :
Once this observation phase is over, you should have a small idea of where to start your first pan tests. Now is the time to get to work. In reality, there is no “best place” to find gold. Its deposition can sometimes surprise you, as can its absence. While the theory is simple enough, in practice there may be factors that escape us.
The different zones in which you have to prospect :
The gravel bar :
I told you about the traps that I call “active” because they load up with material and sort directly by the effect of the current. I’ll tell you about the gravel bar, which has a more “passive” effect on the gold deposit. The presence of a gravel bar at a point in the stream indicates a slowing down of the current and therefore an accumulation of materials of all kinds. As the water level rises and the flow increases, it will become loaded with pebbles, sand, alluvium and gold. The pebbles initially present will play the role of gold traps.
As easy as gold panning is on a gravel bar, the concentration of gold is uncertain. From a theoretical point of view, gold will tend to be found upstream of the bench. Because of the accumulation of material over the seasons, there was no real sorting because it is just deposit. The gold will tend to infiltrate over time through the depths of the bench until it reaches the bedrock (thus inaccessible with the means used in gold panning for leisure).
In addition, a gravel bench is mobile. If a flood is stronger than usual, it can completely destroy or even wash away an entire bank and move it several hundred meters further downstream.
A gravel bank is not especially easy to gold pan:
This is how deposits are renewed. To explore a bench, one must look for an imposing rock (bulder) or an apparent piece of bedrock and sort the gravel just behind it, in order to maximize the chances of finding a deposit. Despite its lack of stability, it is still interesting to explore a bench. Be aware that when you exploit it, you will have to process a lot of volume to have a decent harvest…
It will just be necessary to check that this rock is not likely to move during floods. Most of the time, these rocks are partially, or even almost entirely, covered with gravel and pebbles, which will be a good thing because, with the gold lodged behind, they will have had time to concentrate. In general, because all places are not the same, a gravel bar is above all a zone of accumulation. During floods, the current will bring all the alluvium down on this zone (lull zone).
Beware of fine particles :
These gravels let the finest minerals such as gold (of course) but also silts and clays to the bottom. If you dig deep into the bench, you will first have gravel and pebbles on the surface, then you will arrive in an area where there will be only clay and silt (orange-colored and sandy enough compact). If you reach this layer, continue on as this clay bed is a sign that the bedrock is not far away.
And if you get to the bedrock, you’ll have a good chance of finding a lot of gold that has been seeping in for tens or even hundreds of years. That said, the choice of digging is yours, the depth of the layer is impossible to predict and the scope of the work can quickly become titanic.
Slowdown zones :
The areas of current slowing down can sometimes be interesting but they can be really huge. This slowing down is often due to a rising bed floor or a widening of the banks. This will decrease the pressure of the current and thus the settling of materials that will settle to the bottom by gravity and a weaker current.
The big problem in these areas is that there can be a lot of bottom, a strong current and the bedrock is never visible (covered with so many pebbles and other alluvial deposits). Gravel extraction can quickly become difficult but the gold is well below.
The banks :
The banks are the edges of the body of water. They are often found on the inner side of a meander, but you can also test the banks outside or when the stream is in a straight line. Gravel deposits are proof of this. These gravel deposits can cover the entire plane of the bank. It is also interesting to test the first grasses (those closest to the water). The roots act as a filter, a bit like a carpet, and retain the gold particles. Remember to replant these plants that you have uprooted, because it is thanks to them that the bank is held in place.
NB: it is important to keep in mind that any zone of gold bearing gravel deposit (and gravel in general), is never fixed. Any deposit brought by a flood can very well be washed out or replaced by a next one. Everything is in perpetual motion. Except in the case of bedrock and bulder, the configuration of a place can change and create new deposits where there were none before. There are thus phenomena of gold concentration, recharging, destruction and accumulation of alluvial deposits.
Beware of the clay bedrock :
We know well the hard and rocky bedrock, but we speak less about the clayey or false bedrock. This one is formed by the accumulation of clay coupled with a very fast drying in its center. This heap thus formed, becomes hard as concrete but remains very brittle. Thereafter, erosion does its work and draws this false bedrock by pots and faults. Of course, if the gold line goes through this path, the gold will be deposited there.
NB: Be careful, a fake bedrock is very fragile. It is therefore strongly advised not to break it at the risk of making it ineffective to trap gold during the next floods.
But clay is sometimes a good gold trap and its color can be a good clue.
To remember !
During this survey, you will need to compare the contents of your sections in the different test locations. You have systematically sorted raw gravel without sieving, which allows you to have a real point of comparison between the volume of gravel and the quantity of gold.
During your prospection, it is absolutely necessary to see as many different places as possible in all possible configurations to draw up a complete diagram of the place where you are. Now that this diagram is clear, the next job will be to find the ideal place to put your washing ramp and empty all the gold rich areas. At that point, as I always say, the math is simple, the more gravel you put in your ramp, the more gold you will harvest. This is the “exploitation” part, the most lucrative in terms of finding but the least interesting in terms of recreation.
Be careful however not to take your sluice box out too quickly. You really need to take the time to understand how the deposit works on your area. Also be careful to think carefully if the use of a ramp is really necessary. A ramp is only useful to treat a large quantity of gravel. For example, if your area is mostly micro-cracks to be treated with a hook, it will be faster to exploit the area of crack in the side, but it is you who will judge the most suitable material.
Make no mistake, gold also knows how to be discreet and hide. It will be with your qualities, your perseverance, your eye and your intuition that you will be able to find it. Don’t expect to harvest 1 gram of gold per day either. It happens, but the reality on the ground is not always like that. Gold panning is learned day by day, outing after outing, and the luck factor also has a lot to do with it. Theory is one thing, but it is only theory …
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