Prospecting for Gold and Heavy Minerals
The Goldspear Method
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This text provides information and illustrations to help the reader understand the basics of prospecting. It covers the distribution, discovery and working of alluvial mineral deposits.

Erosion material
During the formation of the earth. Gold and other valuable minerals were usually deposited within veins in the rocks. Some veins are visible whilst other contain microscopic minerals that have to be processed to reveal them. In comparison to the enormous size of the rocks, the exposed surfaces of the veins are very small and limited and often covered with erosion material such as sand, gravel and growing vegetation.

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Over millions of years, extremes of weather have worn down mountains and hillsides and broken up the rocks. The softer rocks breaking down more readily than the harder ones. This erosion material can be made up of everything from large boulders down to fine gravel, sand, clay and powdered rock. This process releases minerals from the rocks and in time they move down hill and into the rivers that run through the area.

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To visibly find a tiny piece of valuable ore amongst many thousands of pieces of other material is very difficult. With some luck and a keen eye it can be done, but it is a very slow method. It is far more rewarding to prospect the rivers that act as a collecting place for minerals. Just as smoke from a fire is diffused into the air, so minerals from an eroded deposit can be dispursed throughout the ground and eventually finish up in the local river.

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Another way to discover ore and particularly gold ore, is to pan. A few pints of sand and gravel contains millions of particles. A study of the final concentrate of gold in the pan, the amount, size and shape, will indicate whether you should continue your search upstream or downstream With the help of a pan in this simple way, most gold mines have been discovered, so the method works, but it still has a problem. It is still a very slow prospecting method. It takes approximately 15 minutes to complete one panning, plus the time it takes to dig out the gravel. It takes quite a lot of time to dig out and investigate a level of ground about a yard down in a river bed. Gold particles and metal containing minerals such as galena, magnetite, pyrite etc, are heavier than normal sand and gravel and are therefore called heavy minerals. All of these can easily be washed out by panning. In prospecting for gold, these heavy mineral discoveries might be the most important guides.

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Water, which is flowing through erosion material, will concentrate the heavy minerals by washing off the lighter minerals on the top. Along waterways layers of concentrated heavy minerals, including gold, can be found, as well as far up on dry land. These concentrations are left from earlier ancient dried out waterways. The desert sand can behave in a similar manner as flowing water, if it is in a windy area. The common factor for all heavy mineral concentrations is that the quantity increases the closer you are to the original vein and the spread out decreases the farther you are from the vein.

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Let us explain the Goldspear; it is an electronic instrument entirely designed for gold and heavy mineral prospecting. First of all, Goldspear is not an ordinary metal detector. It is a completely new innovation.

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GOLDSPEAR consists of two main components. One electronic control box and one probe with its sensor head. The probe tube is connected to the control box which is fitted with a handle for pushing the probe down into the sand and gravel. The length of the base probe can be extended with extra extensions to fit between the probe and the electronic control box.

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The probe tube is made of stainless steel, 4 feet long and 5/8" in diameter. The waterproof sensor head is fitted to the tube. The sensor head is manufactured from a tungsten carbide and is extremely hard wearing. This is the "antenna" of the Goldspear and it measures the electronic characteristics of every little particle that it touches when it is pushed into the soil. The sensor head measures the electrochemical potential (ECP), and the conductivity of the particles. The signals generated are passed through electrical cables inside the hollow probe or extension, to the electronic control box, where they are analysed and classified.

The electronic control box consists of an extruded hardened aluminum box and is fitted with shock absorbers in soft plastic and a handle. The front panel has two knobs and four indicator lamps and one socket for headphones or a loudspeaker. The unit is rain and splash proof and designed for use in the field. Inside the box is the electronic unit, divided into four detectors. These analise the signals coming from the probe head and the result is instantly indicated by sound and light signals. One detected mineral particle gives one signal, a hundred detections give a hundred signals.

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With the GOLDSPEAR you are counting the number of mineral particles detected in the soil. The metal content or the value of the particles will affect the frequency of the sound signal and the different LED diodes which light up. The first detector reacts for all heavy minerals plus black sand, with a crackling sound and a green light diode. The next detector reacts for low metal content minerals, such as pyrite with a low frequency signal and a red light diode. The next detector reacts for minerals with a higher metal content, such as chalcopyrite, with a higher note and an orange light diode. The fourth detector indicates pure metal, such as gold and platinum, with a high note and a yellow light diode. The prospecting depth of the GOLDSPEAR is only limited to the structure of the soil, which means how deep you are able to probe into the ground. In hard packed sediment it could be difficult to get down, but there is a way to solve this problem. See further on the Chapter "In Rivers". In softer soils, for instance, riverbeds and beach areas, desert sand, etc. it is easier to probe to a deeper level. The probe can be made longer with extensions.

Extensions are manufactured in Dural aluminum which has almost the same strength as a stainless steel tube. Each standard length is 4 feet and a diameter of 5/8". The basic probe end extensions have waterproof joints. The extensions can be connected in a few seconds. Tools are not required. Any number of extensions can be used without interfering with the detecting performance. However if too many extensions are used, it could be impractical to handle.

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Sorting process off sediments
Flowing water will churn up and sift the erosion material. Rapid rivers, which start high up in the mountains, "pick up" this material and move it downstream. The more rapid the water, the greater the amount of larger and heavier material will be brought down. When small rapid rivers join larger rivers, the speed of the flow is usually slowed down, and the ability of the water to carry the material is reduced. The water then drops its material which forms deposits or sediments. Coarser material, stones and gravel, are not transported as far as the finer material, sand and micro-gold, which is often transported all the way out to sea, where it is deposited. Consequently, materials in river beds are: mainly rocks and stones in rapid mountain rivers, gravel and sand in larger, wider rivers, sand and clay in deltas and lakes.
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On the beach
The waves are continuously eroding the shoreline. Gold and other heavy minerals will usually be diverted into layers or pockets. Lighter sand will be washed further and further out to sea. The GOLDSPEAR is most effective when prospecting for heavy mineral concentrations of this kind. A large area can quickly be researched to a good depth in the sand.

Ancient shorelines higher up on the land and all river beds are also easy to penetrate. With the GOLDSPEAR, placer deposits of heavy minerals can soon be discovered; it is where the most indications appear. It is in these placers where testing and panning should be done for evaluation. If the heavy minerals contain gold and its origin is going to be discovered, the tracks have to be followed upstream.

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Along the river
Prospecting along the river varies a little from beach prospecting. In the river beds the concentrations of heavy minerals can vary due to other natural reasons, for instance behind large stone blocks, in the inner bends or in any place where the water speed slows down. It is obviously a good thing to have knowledge of these places which are the first target for prospecting with the GOLDSPEAR.

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For investigating deposits downstream, from high banks or rocks away from the shore that are difficult to reach, it is convenient to lengthen the probe with extensions. It is also useful when testing deep river beds. In principle most concentrations and heavy minerals are found where the water is deep. As mentioned previously, where the GOLDSPEAR gives the most indications, further analyzing should be done by sampling or panning.

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Sand and gravel banks in and along the waterways are very suitable to prospect with the GOLDSPEAR. After research it can soon be evaluated where the samples should be taken. There are many situations where the GOLDSPEAR method is very efficient.

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In small rivers
All important places in small rivers or streams should be tested as previously described but a problem can arise when the material is very coarse and it starts to be difficult to probe in the ground. There are ways to get around these problems: during the spring floods, the clumps of grass are often covered by water. During this period the water usually carries more material. The grass tufts are very good traps for gold and heavy minerals. The tufts are easy to test with the GOLDSPEAR. They are almost made for this kind of prospecting. An alternative could be to dig them up with the roots, break them in pieces and pan them. However, this is quite time consuming and difficult. If there are gold fragments in these grass tufts, it is good evidence of further gold bearing areas upstream.

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On dry land
Normally, prospecting is done upstream until the heavy material (which is a target for prospecting) no longer exists. The next step will be to investigate on which side of the stream the mineral originates. In previous times samples were usually taken using a certain pattern. The material was carried down to the water for panning. Today, by using the GOLDSPEAR in the same pattern, counting all indications from the GOLDSPEAR, the same research will be 100 times faster. From time to time obviously some test panning has to be done, but it is only necessary where the highest concentrations of indications appear. The closer to the origin of the ore vein, the more the indications.

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In the desert
Many areas previously under the sea or river deltas are today desert. The water has disappeared, but heavy minerals and gold are still there. Some of the concentrations which previously were created by the water movements are today partly moved around by the winds. Knowledge of this process is obviously beneficial, but we are not going to learn more of it here. To do prospecting in the desert areas is almost the same as earlier described, probe deep down in the sand, counting the indications and test the soil where there are the most responses. The time saved by using the GOLDSPEAR in this case is enormous.

Wintertime (in the nothern hemisphere)
The picture speaks for itself. The alternatives, if there are any, are very few.

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GOLDSPEAR is supplied with one year limited warranty.


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