How to find native gold. Encyclopedia of radio electronics and electrical engineering

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In recent years, Russia has shown a steady rise in gold production, entering the top five countries - the main producers of this precious metal. About 700 gold mining enterprises of the country annually produce about 170 tons of gold. Approximately half of the gold is extracted from ores, and half from placers.

There are a lot of non-industrial placers in Russia, which no one is dealing with yet. Non-industrial placers are understood to mean placers in which there are no reserves for industrial production, i.e. gold mining using industrial equipment (excavators, bulldozers, dredges, etc.)

First of all, these are placers, from which commercial reserves have already been extracted. However, a lot of gold still remains in them. Quite often, a lot of gold remains in the sides of open pits, since the existing legislation does not allow the enterprise to go beyond the contours of the open pit. Gold remains in the dumps of the washed rock. In addition, in Soviet times, during exploration, many small placers were found in remote areas, which, in terms of gold reserves (several kilograms), cannot be considered industrial. For amateurs, oblique placers are also of interest, where flake gold is deposited after each flood.

If you intend to start looking for gold, first of all, you should decide on the place where you will work. Where there is no gold, you will not find it. You should study the relevant literature, collect materials on old and new mines, find out where nuggets were found, and where there was only fine gold (the metal detector does not react to it).

Where is gold found?

One of the sources of gold on earth are quartz veins containing gold. These veins formed hundreds of millions of years ago and have since been weathered by heat and cold, plants and animals, rain and wind, snow and ice. As a result, rich gold-bearing veins collapsed, quartz rock with gold was washed away by water into the rivers. Powerful streams of water during heavy rains create a continuous movement of stones, breaking and rolling them and sorting them by size, shape and density. Gold, being much heavier than many other materials, tends to deposit in certain places along the flow. Such deposits are called alluvial.

Finding and mining such deposits requires an understanding of where heavy materials will accumulate as they are moved by the flow of water.

Directly in the vein, gold has a crystalline form. Once in the river, it often separates from the quartz and takes on a rounded shape. Experienced geologists can tell quite accurately by the roundness of a nugget how long it traveled along the river and where the main vein may be.

There are several types of gold deposits resulting from the weathering of veins.

1. Residual depositsI. These are pieces of a vein that were formed as a result of chemical and physical weathering of a gold-bearing vein and are located in close proximity to it.

2. Eluvial deposits. They consist of these pieces and individual nuggets, which, under the influence of the forces of nature, have moved from the vein, but have not yet been smuggled into the river. Fragments of the destruction of the vein are often located on the slope of the mountain below the original vein.

3. Terass deposits. Reaching the river, gold is deposited at the bottom. The river cuts deeper into the earth over time. As a result, the old river bottom is high above the water level. These are the so-called terraces. Often terraces lie low above the water level. However, some terraces are found far from the modern river. Sometimes these are the remains of ancient rivers that flowed millions of years ago before the formation of the modern river system. Sometimes such terraces are on the tops of mountains, in deserts, etc. As a rule, ancient terraces are distinguished by a high gold content.

Most of the surface gold mining operations today are associated with the development of terraced deposits. The reason for this is that the presence of old bottom sediments is evidence that they have not yet been mined. Any gold that has been deposited is still in place.

4. Bottom sediments. In order to discuss what happens to gold when it enters a stream of water, it is first necessary to understand two concepts - raft and deposits. Many millions of years ago, when the earth cooled, the outer surface hardened into solid rock. Subsequent layers of sand, gravel, stones on it are called deposits or sedimentary rocks. In some places, the sedimentary rocks are hundreds of meters thick. In other places, especially in the mountains and on the coasts of the seas, bedrock volcanic rocks are often completely exposed.

Rice. 45. Moving gold from a weathered vein to a river

The bottom of the rivers consists of stones, sand, gravel, clay (sedimentary formations), which everywhere lie on the bedrock (raft).

Heavy rains in mountainous areas usually cause very strong water currents that wash away sediment down to bedrock. This leads to gradual erosion of the bottom and deepening of the riverbed for a long time. In addition, water flows from the mountains wash away more and more portions of gold into the river, where it mixes with other materials. At the same time, gold, being heavier than these materials, in the process of moving gravel and sand along the river, quickly goes down to the bottom, where it is delayed by the irregularities of the bedrock.

Since gold is 6-7 times heavier than the other materials surrounding it, it takes disproportionately more effort to move it down the river compared to the stone material. Therefore, even during heavy rains, when the water in the river rises and begins to erode sedimentary deposits at the bottom with greater force and carry stones and pebbles, gold nuggets lying on the raft often remain motionless.

In the event that the force of the flow is sufficient to move the gold as well, it can be deposited elsewhere, where the force of the flow weakens.

Traps of gold on the raft

Bottom irregularities play a big role in gold accumulation. Water currents capable of moving gold usually wash away these bumps from clay and sand, leaving room only for gold.

Some types of rocks form a large number of irregularities, providing numerous traps for gold. Particularly effective are cracks and protrusions located perpendicular to the flow.

Obstacles in the flow path, such as a large rock, slow down the flow and may allow gold to deposit in front of or behind it.

One of the most common places in a river to find gold is where a raft forms a cliff into a deep pool. Any place where a fixed volume of water suddenly flows into a significantly large volume of water, or a place where the flow slows down, is a trap for gold, which can accumulate in these places in large quantities. So a waterfall can have a significant accumulation of gold, but not always. Sometimes the water creates such strong turbulence that any gold that gets into the hole under the waterfall during a flood will wash out. On the other hand, there may be large boulders in the pit that protect the gold from being washed away. In this case, you will be very lucky.

Rice. 46. ​​Irregularities of the river bottom - traps of transported gold

In some cases, gold washed out of a pit under a waterfall may settle just behind the pit, where the current has not yet gained sufficient speed. Sometimes in hot weather, the streams become shallow and the pit under the waterfall contains little water, allowing you to rake nuggets out of it.

Rice. 47. Catching gold in a hole under a waterfall

Another common place where gold can be deposited is where a stream flowing down a hillside suddenly breaks into a plain. Such places can also contain large amounts of gold.

Rice. 48. Deposition of gold at the transition of a mountain stream to a plain

Ways of movement of gold

Because of its gravity, gold moves along the river along the path of least resistance. In most cases, this is the shortest distance between large bends in the river. It is deposited on the spits of the inner bends of the river. If there are large stones in the way of gold, then gold can accumulate under some of them. It may not be under other stones.

Rice. 49. Depositing gold on river spits

Rice. 50. Depositing gold near large boulders

When a river or stream suddenly widens, gold can also settle there, as the speed of the water drops sharply. Large stones are often found in this place for the same reason.

ancient rivers

About 2 million years ago, the river system was very different from the modern one. Ancient rivers eroded gold veins and accumulated rich deposits. But the relief of the earth was changing. The channels of some rivers ended up on the tops of mountains, others - in the modern desert. Only a few rivers remained close to the modern drainage system.

Most of the gold in today's rivers is gold from the sediments of ancient channels through which the rivers now flow.

The deposits of ancient rivers contain a lot of gold. And where modern rivers cross such sediments, there is also a lot of gold.

Ancient terraces usually contain a very gold-rich bottom layer. This layer usually has a dark blue color - this is a characteristic sign of an ancient channel. Ancient blue pebbles usually oxidize and turn rusty red when dug out and exposed to air. Often the gravel of ancient terraces is very hard and dense.

Most of the high terraces are the remains of modern rivers. They formed from 1 years to 500 years ago. They are usually developed with hydromonitors. Dredges are used to develop bottom sediments. In both cases, only 000-10% of gold is captured. The rest of the gold, along with waste rock, is lost, going to dumps, where it is available for artisanal mining using metal detectors.

Equipment for the search for nuggets

Abroad, the search and extraction of gold with the help of metal detectors and mini-drags has become a fashionable activity since the late 70s, when the price of gold rose to $ 800 per ounce.

Unfortunately, conventional metal detectors find native gold with difficulty. Therefore, all leading companies have developed specialized metal detectors for gold prospecting. Large nuggets can be found at a depth of up to 1 m, and small ones (the size of a pellet) at a depth of 8-15 cm. Such devices can also be tuned from medium-sized iron, which is found in large quantities in the mines, and from black magnetite sand characteristic of gold deposits.

Rice. 51. Search for nuggets with a metal detector (website kladoiskatel.ru)

To search for nuggets, it is recommended to use the following metal detectors:

1. Gold Master and GMT (White's).

2. Lobo Super Track (Tesoro).

3. Gold Bug 2 (Fisher),

4. Stinger (Garrett).

If the soil is highly mineralized and these devices do not allow to achieve effective work on it, then it is recommended to use Minelab devices - SD 2000, SD 2200, GP 3500, GPX 4000. These devices are more expensive and heavier, the detection depth is the same as that of the above devices , but their main

the advantage is that they almost do not react to the ground. Although a metal detector is fairly easy to use, it takes some practice to learn how to use it effectively to find gold.

Features of using a metal detector when searching for nuggets

Finding nuggets is different from finding coins. The device detects a large nugget without difficulty, however, unfortunately, most nuggets are small, often smaller than a match head. They cause only a slight change in the threshold background, which you should catch. Despite the abundance of metal debris in the mines, the search should be carried out in the "All metals" mode, i.e. without discrimination. This is due to the fact that the electrical conductivities of iron and native gold are almost the same, and by detuning from iron, you lose gold as well.

Secondly, you should work with headphones. Only with their help you will be able to detect small and deep nuggets, especially where the soil is mineralized and creates disturbing noise.

Sensitivity should not be too high. Otherwise, there are many false signals from the ground, which you waste time checking. Lower sensitivity gives deeper penetration into mineralized ground.

One of the most important factors when looking for nuggets is setting the right ground balance and maintaining it throughout the job.

Without proper ground balancing, you won't find a nugget. Set the device to medium ground. With a properly adjusted threshold, you hear a soft background sound. This must be done before the "ground balance" adjustment. Then, if you bring the coil close to the ground, the threshold background may increase or decrease. This indicates that it is necessary to adjust the "ground balance" using the appropriate knob.

In the mines, as a rule, the mineralization of the pound often changes and the device must be re-adjusted every 5-6 m. If the noise increased during your movement, then the soil became less mineralized. If the noise subsided, then the mineralization increased. Over time, you will learn to recognize the moment when you need to adjust the "ground balance".

Sometimes the best result is obtained if you adjust the "ground balance" with the slope in the positive area. This gives increased sensitivity to small nuggets when searching in areas with little mineralization. In practice, this means a louder threshold as the coil approaches the ground. You can't do this simply with the threshold adjustment knob. Rotate the "Ground Balance" knob.

When working on highly mineralized ground, try to adjust the "ground balance" to a negative area. This will reduce your sensitivity to small nuggets, but will allow you to find nuggets that you might not otherwise find.

Rice. 52. Stone brushes in the river bed - ideal gold traps (website kladoiskatel.ru)

It is recommended to have a small nugget (4-5 mm in size) with you and use it when setting up the device. If you do not have a nugget, you can successfully use a piece of lead for this purpose.

Keep the coil as close to the ground as possible during operation. After receiving the signal, scan the object in different directions. If the signal is heard only in a certain direction of movement of the coil, then this is definitely not a nugget. If the signal suddenly disappears when the coil is raised above the ground, then this is also not a nugget and not metal at all. The signal from the metal attenuates gradually when the coil is raised.

Pay special attention to very weak signals, as they most often indicate the presence of a nugget.

Coils should be moved at a slow speed, much less than when searching for coins.

hot stones

In addition to metal debris, when searching for nuggets, the so-called hot stones are very annoying. These are pieces of rock whose mineralization is very different from the average mineralization that your device is set to. Therefore, they give a sound signal similar to the signal from a nugget. Hot stones can be of various sizes and colors. The signal from such stones quickly decays when the coil is raised, unlike the signal from metal. Also, the signal from metal is clearer, while hot rocks give a more "smeared" signal when you pass the coil over it. Often, stones give a signal when the coil is moved only in one direction, while the signal from a nugget is heard with any movement of the coil over it.

Finally, by lowering the sensitivity of the device, it is possible to achieve that the signal from the stone disappears, while the signal from the nugget will still be audible, albeit attenuated.

So with practice you will be able to spot most hot rocks and not waste time digging them up.

Search on the job site of hydromonitors

When looking for gold with a metal detector, perhaps the most productive places are those places where gold was once mined by washing away the rock with a hydromonitor. Often the rock is washed away to the raft. This makes it possible to investigate with the help of the instrument all the cracks and other traps of gold, which often gives excellent results.

In the process of such searches, pay attention to the color of the dirt, which is typical for areas with gold. Often it has a certain color, and then you can look for such places only by the color of the soil and then check them with a metal detector.

Dump Search

When extracting gold with the help of a dredge, only relatively small rock was used to extract gold, and large pieces the size of a fist and more went to the dump. Together with them, large nuggets often went to the dump. Those nuggets that were on the surface have already been found, but in the dumps you can find more nuggets with a metal detector at a depth of up to 50 cm. If possible, the dumps can be cut with a bulldozer. checking the ground with a metal detector after each pass.

Wash trays

Whether you're looking for gold with a metal detector or retrieving it with a mini dredger, the tray is still one of the most useful tools used by prospectors today. The tray is primarily needed for sampling gold in different places until you stumble upon an area where you can effectively work with your equipment. In addition, for a non-professional, a tray is the main tool for gold mining, along with a metal detector.

There are many different types of trays on the market. In general, you can use a small bowl or pan to wash gold. But the best results are given by special plastic or metal trays with gold trapping grooves. Trays can be round or rectangular. Iron trays have a number of disadvantages. First, they need to be annealed from time to time to remove fat from the hands. Secondly, they are highly corrosive. They are magnetic, and therefore it is difficult to separate magnetite from gold with a magnet. In such a tray it is impossible to check the presence of a nugget with a metal detector. But you can cook food in them.

Rice. 53. Washing of gold-bearing rock with a tray (website kladoiskatel.ru)

Plastic trays are light, non-magnetic, corrosion-resistant, do not react to a metal detector. The green color of the plastic makes it easier to see the sparkles of gold. Fat from the hands is easily removed with a cotton swab dipped in alcohol or gasoline.

The sizes of large trays range from 15 cm in diameter to 40 cm. A tray with a diameter of 40 cm weighs about 10 kg when fully loaded. Therefore, it is better to use a tray with a diameter of 35 cm. It allows you to work faster. To work with the tray, it is desirable to use a plastic sieve with a mesh size of 12 mm.

In Russia, for a long time, rectangular wooden trays made of larch burned from the inside have been used. The grooves formed during firing successfully trap fine gold.

For professional gold mining, trays are not used, since a small amount of material can be processed per day, however, for amateur mining and for sampling when looking for the most gold-rich places, a tray is a very useful tool. In general, quickly washing sand in trays is an art that anyone can master with time.

Trays allow you to work without water, although this requires a lot of practice. This is especially useful when working on old riverbeds or in the desert where there is no water nearby. As a rule, with the help of a tray, from 30 g to 80 g of gold can be washed in a week of work. But some people are more lucky.

minidrags

Minidrag is a device that works like a vacuum cleaner, allowing you to suck up sand and pebbles from the bottom of the river along with gold, if it is present there, and separate this gold from waste rock

Minidredges vary in size and design, but they all contain 5 main components - a system that provides buoyancy for the installation, an engine that drives a centrifugal pump, an injector, a washing trough that separates gold from waste rock, and an air supply system for breathing underwater. For small mini-dredges that operate in shallow streams, the latter is not required.

The principle of operation of the installation is shown in fig. 54. Water under high pressure through hose A enters the injector. This creates a Venturi effect, which consists in the fact that water is sucked through the injector pipe, while capturing sand and pebbles from the bottom, and enters the grate of the washing trough. The smallest minidrag has a weight of 24 kg. The pump is driven by a 2 hp two-stroke engine. Suction hose diameter - 50 mm. Productivity - about 100 kg of material an hour.

Rice. 54. The principle of the minidredge

The larger minidredge weighs about 90 kg. Hose diameter - 100 mm. Under ideal conditions, it can process about 1000 kg of material per hour. In reality, such ideal conditions are very rare. In practice, one has to move large stones, loosen bottom sediments, etc.

Rice. 55 Minidrag

Abroad (in Canada, the USA, Brazil, New Guinea), such mini-dredges have gained great popularity and are successfully used for gold mining in shallow waters.

Probe of gold

This is a different type of electronic gold detecting device than a metal detector. It is a probe, at one end of which there is a sensor device that senses the presence of gold in the soil, and at the other end there is a handle and an electronic unit with controls. When the probe is stuck into the ground, and its touch sensor comes into contact with gold particles, the instrument's speaker emits a specific sound signal and the lamp lights up. When magnetite is present in the soil, the sound tone changes and the light signal changes color.

Unlike conventional metal detectors, the sensor of this device must be in direct contact with a gold particle in order for a positive signal to appear, indicating the presence of gold. Gold particles can be very small, which are not captured by a conventional metal detector.

Rice. 56. Probe of gold. Rice. 57. Finding gold with a probe

The device is adjusted so that it gives characteristic signals for gold, platinum, mercury and black sand.

In some cases, the device is very useful, in others - it is impossible to use it (dense soil, stones). It allows, however, to find areas with signs of gold. Can be dropped into water. An additional 120 cm extension is included in the kit.

The main problems in amateur gold mining in Russia

Despite the huge number of non-industrial placers, legal mining of gold from them by amateurs is currently impossible. The reason is that the mining of non-industrial placers is not provided for by Russian legislation. Here is what the candidate of geol.-mineral, sciences of OJSC "Irgiredmet" B.K. Kavchik:

"Knowingly non-industrial placer cannot be put up for tender, therefore, it is impossible to obtain a license for it, and if there are no approved reserves, then gold mining cannot be legal, since only explored and approved reserves can be mined. In general, all Russian legislation from licensing to the rules of gold preservation, it is focused exclusively on industrial deposits. And since there are no industrial reserves in a non-industrial placer, by definition, the entire chain of Russian laws turns out to be inapplicable."

Due to the existing legislative "hole" a huge number of non-industrial placers are currently not being developed. Remains of gold are sometimes buried for the purpose of reclamation of disturbed lands, and spit gold is carried into the sea. Separate developments of non-industrial placers are carried out secretly, bypassing the law ...

At present, the Union of Gold Producers of the Russian Federation has raised the issue of revising the legislation on precious metals and has given specific recommendations for changing the legislation. It is proposed to provide for the issuance of licenses for the extraction of gold from non-commercial placers, allowing to combine the search for enriched gold nests with their mining on a legal basis.

Author: Bulgak L.V.

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