By Dave McCracken

The water flow should be just enough to keep the concentrating action going behind each riffle, yet not so much that the riffles are being swept clean.

Dave McCracken

 

As a general rule, the optimum slope-setting of a sluice is around one inch of drop per linear foot of box. This can change, depending upon the volume and velocity of water being used, and/or the average shape, size, volume or weight (specific gravity) of material that you are processing.

There is no exact formula for setting the proper water velocity through a sluice box which will work optimally under all conditions for all the different types of riffles being used today. Therefore, rather than give you a formula, I will attempt to give you an understanding of what affects the proper amount of water velocity will cause in a sluice box, and also what the affects are of too much or too little water velocity. In this way, you will be able to act from direct observation to ensure that your, or anyone else’s, sluicing device will be recovering gold to the fullest extent possible.

In setting up a sluice, if feasible, it is desirable to have enough water flow to move the material through the box as fast as you can shovel (or dredge) it in at full production speed.

Most of the riffles being used today are designed so that a concentrating-action takes place behind the riffles. By increasing or decreasing the amount of water velocity over a set of riffles, the amount of water-action behind each riffle is also increased or decreased—which has an effect on the amount of concentrating action taking place. Water velocity can be increased by either putting more water through the sluice box or by moving the same amount through faster. Optimally, the water flow is just enough to keep the concentrating action going behind each riffle, yet not so much that the riffles are being swept clean (called “boiling”) of their concentrated material.

How much water velocity is directed over the box directly affects how much material will stay behind the riffles. When the correct amount of water force is being put through a sluice, its riffles will run about half full of material, and the material can be seen to be dancing and vibrating behind the riffles (concentrating) when the water is flowing.

If too little flow of water is directed through a sluice box, not enough water force can get into the riffles and they will “pack up” with material. In this case, little or no concentrating-action will take place and gold recovery will be poor. When this happens, little or no visible vibrating action behind the riffles will be seen and material will not be moving through the box fast enough to allow you to feed the sluice at production speed without loading up the entire box.

Too much force of water through a sluice box will put too much turbulence behind the riffles. This will cause some of the heavier concentrated material to be swept out of the box.

When this happens, gold recovery will also likely suffer, because the areas located behind the riffles are not calm enough to allow some percentage of the finer pieces of gold to settle. You will notice in this case that the dancing action is occurring behind each riffle, but less material will collect behind the riffles because of the increased amount of turbulence there. When you have too much water velocity, as material is shoveled into the box, it passes through very quickly and has little time to make contact with the riffles.

All the above points remain true when adjusting to get the proper amount of water flowing over an expanded metal-riffle system. However, when using such a system, it is necessary to remember that the riffles are very short. So it does not take very much water velocity to make them concentrate properly.

This means that the size of riffles affect how much water velocity is optimum through the box, how much classification of material is necessary and how fine in size your effective gold recovery will be.

The correct amount of flow is usually found to be just enough to move the material over the box to keep up with your feed of material. Since gold is around 6 times heavier than the average material that will pass through a sluice, there is usually some margin for error if velocity is a little faster than necessary. But a faster flow (than necessary) will affect how fine in size your effective gold recovery will be, if fine gold is present.

Once you have your sluice box set up the way you think it ought to be, it is a good idea to run a sizable portion of gold-bearing material through the box and then pan some samples of the tailings. If you do not find any gold in the tailings, you are set up properly. If you are finding gold in the tailings, some changes are in order. Another test is to mix some pieces of lead in with some material, run it through the sluice, and see where the lead stops.

Sluice boxes process material best when receiving it from a steady feed. Too much material dumped at once into a sluice box has a tendency to overload the riffles and choke off the concentrating-action behind the riffles. This will cause gold to wash right through the sluice box as if there were no riffles present at all.

On the other hand, it is not good practice to run volume-amounts of water flow over a sluice box without some material being constantly or regularly fed through. This is because the scouring-action from the water flows will continue to further-concentrate materials trapped behind the riffles, causing heavier materials to be washed out of the box. A sluice box operated for extended periods with no new material being fed to it has an increased chance of losing some of its fine gold values. How much gold loss will depend on a multitude of factors, such as the type of riffle design, how much water flow, the type and weight of concentrates and the size and purity (specific gravity) of the gold.

So if you will not feed more material into your sluice for a while, it is a good idea to cut your water flow back to reduce turbulence behind the riffles until you are ready to feed again.

Even when a sluice box is set properly, occasional larger-sized stones or rocks can become lodged within the riffles. These should be picked or flipped out of the riffles with minimum disturbance to the remaining portion of the sluice.

On most suction dredges, the volume of water being moved through the sluice continues at the same steady flow during production speed. So adjusting the water velocity to set up the dredge right is accomplished by changing the slope of the sluice box itself—which will speed up or slow down the flow of water over the box. Then, once you are dredging, if you will stop feeding streambed material into the suction nozzle for any period of time, it is wise to block the nozzle with a larger-sized cobble to slow the water flow through your sluice box.

When placing a sluice box within a stream or creek for its water flow, the water velocity can be adjusted by either changing the slope of the box, by varying the volume of water being directed through the box, or by placing the sluice at different sites in the stream or creek where the water is moving at different depths and speeds. Getting the right flow of water to pass through a sluice box out in the field is not difficult. But it is sometimes necessary to try different ideas until you find what works best in each situation. For example, in a location where the water is moving slowly, you might be able to direct more water through the sluice and gain the amount of water velocity that you need. In a stream where the flow is moving more swiftly, the water velocity through your box can usually be adjusted by changing the volume of water directed into it, and/or by varying its downward slope.

Usually, you will have little trouble arriving at the correct velocity through your sluice box when placing it in a fast stream of water. You can use river rocks to make a foundation within the stream so your box can sit level from side to side. By allowing different amounts of water volume through the box, and by changing its downward slope, you can work out a combination that does the job. It is good to have a length of nylon cord along with you for securing the sluice box to a rock or some other object upstream. This prevents the box from being moved off its foundation by the force of water. Sometimes it is necessary to pile a rock or two on top of the box to hold it in place. This is especially true when you are using a sluice made out of wood. You can shovel gravel into the box while trying the different combinations to see what effects the changes have on water velocity.

In a situation where you must set your sluice into slower water, you will find it is generally more difficult to get the flow you need, because you have to create more water velocity than is presently there.

If the flow of the stream itself is not enough to move material through your box, you will sometimes find that changing the slope of the box within the stream has little or no effect on speeding up the flow through the sluice. In this situation, there are several things that might be done to channel enough flow through your box so that you can run material through at production speed. Sometimes the flow of water within the overall stream itself is enough, so that by setting up a “water director” in the stream, you can move enough water through the box to give you the desired result. A water deflector, or barrier, like this can sometimes be built by throwing river rocks out into the stream to make more water flow into and through the sluice.

In this situation, there are several things that might be done to channel enough flow through your box so that you can run material through at production speed. Sometimes the flow of water within the overall stream itself is enough, so that by setting up a “water director” in the stream, you can move enough water through the box to give you the desired result. A water deflector, or barrier, like this can sometimes be built by throwing river rocks out into the stream to make more water flow into and through the sluice.

Sometimes you can get the water velocity needed by arranging a small water-elevator across the waterway. By doing so, and by placing your sluice where the moving water spills over the top, you might create more than enough water flow through the box to meet your needs. It really does not take very much volume of water through a medium-sized sluice box to get the right amount of velocity, if the water is moved through the box at speed. In the case of a short elevator (dam), the water level might only need to be raised up slightly to increase the downward slope of the box enough to create the needed water velocity. How high the elevator needs to be depends mostly upon how much water is flowing within the stream or creek.

A sheet or two of thin plastic, or a plastic tarp, or some old rice bags, can come in handy when you are arranging an elevator or water director within a stream. Such material helps prevent the water from pouring through the holes in your man-made barriers.

A water director or elevator can most often be used with good result wherever the water in a stream or creek is moving and is shallow enough that the barriers can be built easily.

If the water at the work site is moving too slowly, or for some reason a water director or elevator will not work in a particular location, it will be necessary to either set up your sluice in a different location where the water is moving faster, or use a motorized pump to feed water into your sluice. Or, in some situations, it is possible to siphon water into your box from a higher point upstream. Siphoning can be done effectively with the use of reinforced garden hose(es), other types of heavy-walled water hose or PVC.

 

 

By George Mullen

 

Desert tortoiseMost traditional methods for recovering gold from gravels require an ample supply of water. However, an old prospector’s adage has it that gold is where you find it. In the southwest, the “where” is all too frequently situated miles from even a trickle of water. Dry-washing of gold-bearing soil or gravel provides an effective solution to this dilemma.

Click here for a more thorough explanation of dry-washing techniques.

The Spaniards used a scheme similar to the winnowing of wheat from chaff and straw. Two men would grab the comers of a blanket, upon which a small quantity of classified gold-bearing material had been placed, and they repeatedly would toss it upward into the air. The wind would blow away the lighter fraction, and any gold and black sands, which are heavier, would fall back onto the blanket. Wool blankets worked best, because the static electrical charge generated by the wool tended to attract fine-sized gold on the blanket’s surface.

The modem prospector uses an efficient tool called a dry-washer to extract the ever-elusive gold particles from screened gravels or other material. Dry-washers can range in size and complexity from hand-shovel-fed models, to large machines serviced by wheeled or tracked front-end loaders.

All dry-washing machines require a low-pressure, high-volume source of air. At the low-cost end, this can be provided by a bellows which is linked to a hand-operated crank or motor-driven fly wheel. At the higher-cost end, the air source is typically provided by a gasoline engine-driven blower. The remaining components of a dry-washer combine to construct a sloped classification screen (or “grizzly”), which routes fine-sized material to a pneumatic sluice box, where a mechanically-modulated flow of air accomplishes the separation of gold from the lighter-weight material which contains no value.

Dry-washing for goldA dry-washer for small-scale prospecting might consist of a rectangular screen with 1/2 inch openings over a sloped trough. The screened material would pass from the lower-end of the trough to the head-end of a sloped riffle tray consisting of cotton fabric stretched over an inner frame. The tray includes sides to contain the flowing material, and its surface is interrupted by five crosswise riffles. Under the tray is a hollow box and the mechanism which modulates air flow through the tray at a rate of about 200 puffs per minute. The rate of air flow is designed to be sufficient to lift lighter material over the riffles, while the gold remains trapped. When everything is working right, the flow of material through the riffle tray resembles water flowing through a conventional sluice box.

My dry-washer was built from a plan published by Carl Fischer. It is mostly constructed of wood and is extremely portable. A small gasoline engine drives the air box via a belt and pulley speed reducer, producing the required 200 puffs of air per minute. The end result is an efficient separator which saves even the finest particles of gold. I have checked the tailings on numerous occasions and have yet to find any significant amount gold in them.

Prospecting for gold in the desert uses techniques similar to those that are used to locate placer gold on flowing streams or within old stream channels. You want to sample dry-washes on pediments to mountains, feeder-canyons in the mountains and ancient streambeds.

Another old prospector’s adage suggests that one should look for gold where it has been found before. This is still sound advice!

Very fine gold is abundant at many sites in the northwest, and the usual methods of final gold recovery do not always work very well. I have found that the screening and drying of dredge or high-banker concentrates, and then running them through my dry-washer, really works well. I use a metal detector to monitor both the feed and the tailings.

After processing pay-dirt material for about an hour, I suggest it is usually a good idea to clean-up the riffles to check your recovery. I use a plastic gold pan and small wash tub for the final clean-up and have operated all day on just a few gallons of water.

My wife, some friends and I operate suction dredges and high-bankers on the extensive New 49’er properties near Happy Camp, California during the summer months, where there is always an abundance of water. Our dry-washer allows us to remain active during the winter, usually around Quartzsite, Arizona. These gold prospecting and mining activities provide enjoyable activity, along with an extra source of income when we need it.

 
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By Dave McCracken

“Good organization always comes back to having some understanding in advance of what conditions you will encounter when it is time to complete the mission.”

 

Assuming legal access to the property has already been arranged, and company executives intend for us to proceed in this way, here are the primary objectives that we try and accomplish during the preliminary evaluation of a potential mining project:

1) Meet with company executives to gain an understanding of what the mining program is about, what the overall objectives are, the timing and the budget. Review the information which they have accumulated so far. Make plans for a departure-date.

2) Obtain the very best maps of the area that we can get our hands on.

3) Locate and study as much information as we can find concerning the mining history of the area, and the areas surrounding where the project will take place. Plot this information on the map. This includes finding out the type of mining methods that were being used, and what kinds of values have been recovered.

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4) Study background information about the geology, weather, culture, politics and economics of the area. This includes a look at the public information released by the U.S. State Department . Follow up with Internet research to see what others have to say about the people, events and mining activity within the area – and anything else of interest.

Is the political situation stable?

5) Establish a preliminary idea of how and where the potential project-area is located in relation to local communities, potential sources of supplies, emergency support, political structure and access. Bring together an early idea of what we want to see when we get there.

6) I always recommend that at least one representative (preferably one of the company directors) of the company accompany us through the full preliminary evaluation of the area where the potential project would take place. It is in the company’s best interest to have someone from existing management present to confirm our observations, and to help evaluate our conclusions.

7) Travel to the potential project area and:

A) Get a feel for the local politics in general, and in relation to the potential project. Will the locals ignore, support or object to the program? Are there pre-existing problems that will need to be fixed before beginning a sampling program? For example, the following video segment shows local campaigning on political issues within Madagascar that soon thereafter evolved into civil strife that disrupted all productive activity in the country for at least 6 months:

B) Find out the different ways of gaining access to the project site. Try and make contact with those people who would provide the transport service (if needed), and establish timing, cost and dependability. How can we make contact with them from the field? For example, the following video segments demonstrate boat transport services we needed to rely upon to support a dredging project in Cambodia :

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C) Locate sources of food, fuel, supplies and personnel to support the mining program. This would include any special needs, like local guides and boat operators out at the project-site. Establish the cost of things and dependability of the supply and/or services. Are there periodic shortages of supplies or services?

    

 

D) Locate the nearest place for competent medical assistance. Do they have any kind of emergency evacuation service? If not, perhaps they can provide a referral to the nearest large medical facility which does provide such a service. Develop a viable plan to provide competent medical care in the event that it may be needed, and how to mobilize the service from the field.

E) Establish support in local communities within the vicinity of where we would conduct the mining operations.

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F) Locate local miners and gain as much information as possible from them about what is being done, where and what results are being accomplished. Purchase samples of the values if possible and carefully log where they came from. Take a hard look at the gold, gemstones or other values being recovered. It is important to verify the activity and results. Look at how much value the locals are recovering, in relation to the volume of their production. Relate that back to what can be accomplished in production with suction dredging or other modern equipment.

    

 

    

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For example, the following video segment demonstrates a primitive hand-mining program that I stumbled upon along the border of western Viet Nam just a short while ago. These miners were breaking very small volumes of hard-rock ore free from the surrounding country rock with a hammer and chisel. The pieces of ore were being crushed by hand, and then surprising amounts of free gold were being panned in the river where we were sampling. While the amount of gold actually being recovered was not a lot, it was very rich compared to the very small amount of ore that was being processed by their primitive methods. Modern equipment and technology would turn this into an extremely valuable deposit:

The best local mining operations to observe are the ones that are actively processing the gravels within the waterway where our dredging would be done in a follow-up sampling operation.

For example, I captured the following video sequence where active gold mining was being done by local miners alongside and inside of the river where we were considering a suction dredge program in Africa several years ago. As the local miners were recovering a lot of gold in proportion to the volume of river gravels being processed, we decided that a follow-up dredge sampling program was justified:

G) Find out if there are special concerns about dangers in the water, within the surrounding area, sanitary problems, health concerns, or security worries. How will they be dealt with? Will there be any special needs for this?

For example, the following two video sequences were captured during a dredge sampling project that we completed in Cambodia several years ago at a time when there was an active (brutal) civil war in progress. The dangerous situation at the time required us to bring along a substantial contingent of security forces and also arm each of the specialists on our team:

Is the waterway full of big rocks that will require specialized equipment to winch out of our way?

    

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H) Free-dive in the river and/or probe from the surface to gain a good perception of what equipment will be needed to perform a preliminary sampling program. How deep and fast is the water? How deep is the streambed material to bedrock? Is there a lot of material too large to move by hand? Are submerged trees going to interfere with the sampling process? Are there excessive amounts of mud or sand that will overwhelm the recovery system?

It is often possible to bring up smaller-sized samples to pan from the bottom of the river, to get a better idea what a dredge sampling program will find.

I) Decide if special recovery methods will be required to perform a preliminary sampling program. If conditions present will mean that more portable equipment will be required, this may require a floating container be constructed to fully catch the samples, so they can be carefully processed on shore.

Or it may be that you can refit your sampling dredge so that it will effectively capture the fine gold from your samples. Here is a substantial explanation of the system which we have developed to effectively recover more fine gold on our conventional suction dredges. It combines two classification screens to more-effectively separate material-feed into three size-fractions, each which is directed into a different recovery system. The smallest gold particles (which are most difficult to recover) are directed into low-profile riffles along the bottom of the sluice box which have long been proven to be very effective at trapping fine gold.

  

J) Establish the potential for a commercial mining opportunity, based upon evaluation of pre-existing information and direct observation of ongoing local mining programs, along with whatever limited sampling can be accomplished using the resources that are immediately available.

K) Document all important details as well as possible by logging names, phone numbers (or email addresses) and locations of important contact persons, along with how much things will cost. Obtain digital images of everything important..

L) If appropriate, conceptualize a preliminary sampling program. This includes how the sampling program would be performed, supported, and how long it would take to complete. The concept should be consistent with the company objectives and budget.

8) Write a report which includes all of the important details of our findings. Include a photo-library with explanations for each image. The report should conclude with a recommendation. For example, Here is an example of the non-proprietary portion of a completed Report.

For a better understanding of why a preliminary evaluation is so important, I strongly encourage you to read about some of the sampling projects that we have accomplished in remote locations outside of America. The full list of the adventures I have written about can be found here . When reading these stories, it should become very clear to you that the potential success of any sampling program will largely come back to how well it is organized in advance. Good organization always comes back to having some understanding in advance of what conditions you will encounter when it is time to complete the mission.

 

 

Article & photos by David Lawler, Consulting’ Geologist

 

Placer deposits image 1Placer gold deposits represent the most attractive targets for small-scale miners and prospectors, since activities can be carried out with reasonably small costs, and encouraging prospecting results can be obtained rapidly. A small-scale miner has the opportunity to exploit small, rich accumulations of gold which larger-sized mining companies might pass by, due to reserve-size and overall ore-grade. In other words, because of the higher costs involved with a larger mining company, they will not be interested in some types of gold deposits which can be quite lucrative for a smaller-scale mining program.

Placer deposits have been exploited by man since early historic times and have remained an important source of gold on the world market into the 20th Century.

Placer deposits have yielded over 60% of the world’s gold production. Placer gold production in California alone during the height of the Gold Rush has been estimated at $81 million dollars. (Dollar-value in terms of $18/ounce in 1849, prior to 150 years of inflation).

While many texts and articles have been written on the subject of placer mining, the purpose of this article is to provide a brief overview of the subject and to introduce relevant facts which have practical application for the small-scale miner. The less common types of placers, e.g., Glacial, Aeolian, Bajada and beach placers will not be covered in this article.

Alluvial Placer Gold Deposits

Placer deposits image 2Definition: Alluvial deposits are the most common type of placer gold deposit. This category includes fluxial (river and stream) placers which formed in well-defined channels. It also includes “bench” or terrace deposits. These are older river or streambeds which formed on the elevated side slopes of drainage valleys. Both ancient (paleo placers) and modern deposits are included in this category and have produced significant amounts of gold.

Characteristics: Good sorting of sediment and gold particles by size and weight.

Sediments tend to be well transported, reflecting significant rounding or flattening of individual particles as a function of distance traveled from its source. The source of gold can either originate from a nearby lode deposit, generally leaving the gold’s surface with a rough texture; or the gold can have originated from distant sources, generally leaving it with smooth, flattened particles, flakes or nuggets.

Ancient Fluvial Placer Deposits

Placer deposits image 3Examples: (Ancient) Tertiary-age Ancestral, Yuba and Feather River systems, Sierra Nevada Mountains, California, Ancestral Klamath River system, Weaverville and Hornbrook basins Klamath Mountains, California. There are also widespread occurrences of other ancient gold-bearing channels in other western states in the U.S.

Prospecting Suggestions: Check areas where modem drainages (rivers, creeks, and gullies) have eroded ancient gold-bearing channel deposits. Many of these areas were worked by miners during the 19th Century, but there is still plenty of gold remaining for the modem-day small-scale miner.

For example, check side slopes of ridges which contain the ancient channel deposits, since these are areas that usually could not be exploited by hydraulic or ground-sluicing mine methods, due to lack of adequate water or water pressure. These virgin (unexploited) areas can produce eroded substantial pockets of placer gold.

Hydraulic Mine Pit areas often contain good prospects for small-scale mining. Check the exposed bedrock floor (representing the exhumed channel base) surfaces both for cracks and weathered cemented gravels. Gold may remain in small fractures and cracks in the bedrock. These areas can be particularly fruitful for electronic prospecting.

In addition, gold may be liberated from previously-cemented gravels after the long period of weathering on the pit floor. Check drain tunnels and tailraces that may have been cut into bedrock or the sides of the channel for several reasons: First, drain tunnels were driven through solid bedrock at the floor of a hydraulic pit to drain excess water and tailings from the working face of a mining excavation.

It is estimated that hydraulic mining methods lost between 30% – 50% of the gold that was liberated from the deposit. In addition, many of the drain tunnels were also used as the primary locations for the placement of elongated sluice box recovery systems. Thus, clean-ups were performed inside the tunnels. Although some of the drain tunnels have become choked with debris or collapsed from weathering, many still carry gold-bearing materials through the tunnels.

Testing and sampling of in-situ (in place) Tertiary gravel placers is one very proven method of locating valuable gold deposits for the serious small-scale mining operation today.

Modem Fluvial Placer Deposits

Placer deposits image 4Examples: Rivers and streams of the Sierra Nevada and Klamath Mountain areas in California.

Prospecting Suggestions: Prospect areas which are adjacent to known ancient channels or lode gold deposits, since modern river deposits will usually become more enriched close to those areas.

Gold-bearing stream and river channels must be examined and studied in detail in regard to their history, habit and special characteristics, in order to better-exploit the placers contained in them. Check available geologic maps of a particular river area or observe the different bedrock types which are present. This information will yield valuable clues to the location and manner of gold accumulation in various stretches of river.

Most modern-day small-scale prospectors are using suction dredges, sluicing gear, vack-mining equipment and/or gold pans to prospect for and develop these types of gold deposits.

Sample bench deposits adjacent to the active stream margin. Although these deposits are not as commonly reworked by stream processes, they often contain high concentrations of placer gold. Thick bench deposits containing gold-bearing material derived from hydraulic mines are still present along the margins of rivers and streams in the Sierra Nevada and Klamath Mountain regions of California.

Residual Placer Deposits

Placer deposits image 5Definition: Shallow mineral deposits forming directly from weathering and chemical disintegration of a gold-bearing quality vein near the surface. Residual deposits tend to be rich, but localized in occurrence, i.e., close to the vein or outcrop area. These are also termed “seam diggings” due to their occurrence in weathered gold-bearing quartz stringers contained in weathered schist and slate fracture-zones.

Examples: “Seam digging”s at Georgia Slide, Spanish Dry Diggings and French Hill areas, Georgetown Divide, El’Dorado County, California, Alleghany and Downieville districts, Sierra County, California, Humboldt Mountains area, Humboldt County, Nevada.

Prospecting Suggestions: Search in lode gold districts characterized by small high-grade gold-quartz vein pocket deposits. Focus your search into specific areas which are along the geologic trend of previously-exploited lode pocket deposits. Recent fires, landslides, or disturbance by logging operations are constantly exposing new virgin areas for prospecting.

Modern-day metal detectors may help in the exploration and exploitation of these deposits, due to shallow overburden and erratic distribution of the residual placer nuggets.

Eluvial (hill-slope) Placer Deposits

Placer deposits image 6Definition: Deposits representing the transitional stages between a residual and alluvial placer deposit (deposits which form in route between the lode erosion and drainage system). Residual gold tends to form accumulations in soil or colluvium by “creeping” along with material down a hill-slope.

Examples: Klamath Mountain region, California and Oregon.

Prospecting Suggestions: A metal detector can be the ideal tool for locating these deposits, since gold distribution tends to be spotty or erratic due to a poor degree of sorting and transportation. High-banking equipment can be very productive where an adequate water source is available nearby. Dry-washing equipment can be productive in places where there is no water available for processing. Mechanized earth-moving equipment is sometimes necessary to excavate thick eluvial deposits. In this case, small wash plants are being used to recover the gold.

Recommended Reading

Averill C. v: 1946, Placer Mining for Gold in California: California Div. Mines Bull. 135, 377 p.

Clark, B. 1965, Tertiary Channels: California: Div. Mines and Geology Mineral Inf. Service, Z 18

Clark, B. 1970, Gold Districts of California: California Division of Mines Bull. 193, 186 p.

Haley, C.S., 1923, Gold Placers of California: California Mining Bur. Bull. 92, 167 p. Jenkins, O.P., 1946, Geology of Placer Deposits, in Averill, C. Z Placer Mining for Gold in California: California Div. Mines Bull. 135 p, p. 147-216.

Lindgren, 1911, The Tertiary Gravels of the Sierra Nevada of California: U.S. Geol. Survey Prof. Paper 73, 226 p.

Whitney, J.D., 1880, The Auriferous Gravels of the Sierra Nevada of California: Harvard Coll. Mus. Comp. Zoology Mem. v. 6, no 1, 569p.

 

By Dave McCracken

There is always action and controversy of some kind going on in the gold mining business. I guess that’s why most of us like it so much!

One thing about participating in gold mining or prospecting, is that it is never boring. Nor is any part of the administration of the gold mining industry boring. There is always some action going on!

This is one of the things which makes our industry so interesting. People who participate tend to be non-conformists by nature, or at least on a temporary non-conformist quest of some kind.

Some people get involved in gold prospecting as an escape from the humdrum of their normal, everyday existence; get up early, go to work, come home, watch TV and go to bed, try and pay the bills on time, etc.

Getting out into the great outdoors on a quest for adventure, even on the most remote possibility that something of value may be found, is enough of a lure for many to pursue prospecting activities. In some cases, it is not the gold which is of primary importance. When found, the gold is just a bonus to many participants. The real treasure is the opportunity to get physically and emotionally free of our normal, everyday existence. This is refreshing and revitalizing. It gives us a chance to put things back in a more balanced perspective.

It’s been said that the best way to solve a problem is to get outside of the problem and view it from the outside. Sometimes it’s not enough to take a walk or go for a drive. Sometimes, the best way to get out of a problem, or to be able to view a whole existence from the outside, is to launch yourself into a new adventure or a new existence. After a few days on a quest, or in a complete new environment, or after a few days in a brand new dramatic activity, you can often look back at earlier problems, or your normal life, and see them far more clearly. Everyone can gain from an exciting vacation or experience.

Different people gain different things from being involved with our activity. While one person might get back in touch with the basics of nature, another might connect with the historical values of those who were there many years ago. Others enjoy the search and the excitement of the potential find. Some are emotionally disappointed in not finding what they are looking for. But everyone is touched in some way. These activities are never dull.

Even the guy that wasn’t able to find any gold this time, while perhaps disappointed at this moment, at the same time he is not all caught up in the problems at the office. He stopped thinking about the office last week. Right now, he is planning his next adventure in such a way as to improve the amount of gold he will find.

There can be more to life than normal survival routines, raising the family, earning the pension and paying off the house. This is where dreams come in. Take a person’s dreams away and you have destroyed that person. It is not only about how much gold the person finds. It is the fact that the person desires and is interested in going out looking. This is therapy; a person pursuing his or her dreams, no matter how silly or inconsequential those dreams may be to others with dissimilar interests.

Being involved with the administration of the industry is not dull, either! People associated with this business are either friendly and supportive, or they are out to do us in. The controversy over the 1872 Mining Law is just one example; those people who are against us will invent just about any lie or excuse why all mining should be stopped. There is no middle ground. There is no reason. But there is drama; plenty of it!

And this is the way our whole industry is. Some people are excited. Some people are disappointed. Some people like us. Some people hate us. Some people want to tell you the whole story about the rich gold deposit they are looking for. Some people are incredibly secretive. Some people want to share the gold deposit they located with all the other miners and friends in the area. Others want to keep all the gold for themselves. Some people want to argue and complain about what the problems are that face our industry. Others are willing to pitch in and give a hand to help resolve problems. But there is always action and controversy of some kind going on. Gold mining is never boring. I guess that’s why most of us like it so much!

 

BY STEVE HICKS

Placer miners at work

Placer mining is relatively simple as long as you don’t expect to make a profit; but it becomes much more difficult if your intention is to make some money. If you want to make some money, it’s a lot easier and cheaper to learn from other people’s mistakes, than to put yourself through the school of hard knocks. By far, the most common mistake I see is inadequate or improper sampling, which is often due to gold fever. Other mistakes are: not properly cleaning up bedrock, not researching the past mining history of your area, and starting a mining venture under-funded.

Placer miners diggingFirst, we will cover sampling. A common remark I hear is why put the time, effort, money, etc. into sampling when it can be better-spent on actual mining and making some money? All too often, individuals lose thousands of dollars on their mining ventures; but had they done some sampling and found out that the ground was too low-grade to mine profitably, they would have only spent hundreds of dollars. I have seen an individual go broke trying to mine ground containing less than $2 of gold per yard when there was un-mined ground about 300 yards away running slightly over $100 per yard. That is not a typographical error; it is one hundred dollars. This is, of course, an extreme example; but all too often rich ground is missed. Even before sampling, a literature-search is in order to get an idea of the ground’s value.

Another common mistake is not separating overburden from pay gravels. Novice miners frequently like to run low-grade overburden. This is because the more gravel they mine, the more gold they recover. While mining everything on a property will maximize the amount of recovered gold, it could bankrupt a person at the same time. If the overburden only contains $2 of gold per yard, and your mining cost is $5 per yard, then you are losing $3 for every yard put through the wash plant.

On the other hand, if you can strip low-grade overburden for $1 per yard, then you have saved $2 per yard which can be directed toward mining the pay gravels.

Gold sample in panOften, new miners leave a lot of gold values in the bedrock. Some highly-fractured bedrock may have values several feet below the surface. The deepest I have ever read about was a Canadian mine going down nine feet into bedrock to get all of the values.

Most often, the bedrock values will be in the top two feet of bedrock. Once you mine the top six inches, check the next six inches to see if there are still enough values to make it pay. Once again, you must evaluate your mining costs for ripping up bedrock to determine if the effort will pay adequate dividends.

Starting a placer operation under-funded is another common mistake of novice miners. It is a mistake to count on finding some profitable ground to pay off debts right away and carry you through the rest of the season. Unforeseen problems have a way of cropping up, such as equipment breakdowns or a severe water shortage later in the season.

Even though most individuals reading this article won’t be running a large-scale mining operation, these tips should help you toward a more profitable operation even on a smaller-scale. Maybe, with some increased sampling or more efficient mining, you just may find that big nugget this season!

About the Author: Steve Hicks is a geologist specializing in sampling gold placers. He has previously worked a number of years as a mineral examiner for the BLM in Alaska and Montana. Presently he is doing placer consulting work and residing in Livingston, Montana.

 

BY DAVID KAREJWA

 

 

Dredging is very hard and tedious work at its best. The more we dredge, the more we realize how much time is actually spent moving oversized material out of the way.

Some pay-streaks don’t have any large boulders at all. Then again, some pay-streaks have an abundance of boulders—many of which are too large to move by hand. When this is the case, gold production results no longer depend on how well you can operate a suction nozzle; they depend on how efficiently the boulders can be moved out of the way.

Many of us started by using two-ton come-alongs to pull the boulders out of the way. And while this may work fine on a very small-scale operation, or an operation which only runs across an occasional boulder, it does not work well at all on a commercial scale.

Pay-streaks can be time and energy-consuming to find in the first place. Being ineffective at moving the boulders out of the way can greatly lessen a dredger’s ability to succeed. I have been dredging on a somewhat serious level on the Klamath River during the past four or five years along with a number of other serious dredgers. Together, we have innovated new boulder-pulling equipment concepts which have improved our sampling and production capabilities to an enormous degree.

The most comprehensive demonstration of underwater dredging I have ever seen is contained in Dave McCracken’s video, ” Advanced Dredging and Sampling Techniques.” Detailed winching and rigging techniques are also fully laid out with diagrams in Dave’s book, “Advanced Dredging, Volume 2.” These are highly recommended for those of you who will get serious about winching.

We found that a winch can be mounted on a floating platform, and the platform can be anchored out in the river behind our dredge hole. We use an electric winch in most cases, but new designs are including hydraulic winches.

The platform is anchored to the rear—either by cabling it to a boulder or a tree on the bank, a boulder or a group of boulders in the river, or to a dead-man placed in the river with tailings from the dredge dumped on top to anchor it.

The winch cable and boulder-harness extends down into the dredge hole. Also, the winch controls, on a cable, are waterproofed, and extend down into the dredge hole. When a boulder needs to be winched out of the hole, it is just a matter of slinging it, and winching it back, with all of the winch controls directly at your fingertips. This greatly improves the situation over having to put an additional person up on the bank to operate the controls of a mechanical winch, having to give signals, etc. It allows for single-person operations. While I don’t advocate people dredging alone, a lot of people do. If you are one of them, with this system, you are able to dredge for awhile; and when a boulder needs to be winched, you can simply sling it and drag it out of the way—just like that.

The old way required single-dredgers to sling the boulder, then go up onto the bank to operate the winch. When the boulder got jammed against some obstruction along the river-bottom, the person would have to go back into the water, try to free it up, back to the winch, back and forth, etc., until the boulder was finally moved out of the water. It was a nightmare!

One excellent advantage to a floating winch, we have found, is that the pull is also in an upward direction on the boulder. This helps slide the boulder more easily because of less friction along the river bottom. It also helps get the boulders pulled up and over other obstacles. Consequently, there are fewer problems with the boulder being jammed up while it is being pulled.

Floating winch platforms are relatively inexpensive and easy to construct. They don’t generally need to have much more flotation and size than an average 6-inch dredge. They are not very heavy, and they are easy to float around in the river. In fact, we use the extra deck space on ours to store our extra dredging and cleanup equipment, extra gas, etc.; the things we don’t like cluttering up the decks of our dredge. We place a portable motorized electric generator on the winch platform to keep the winch battery fully charged while we are diving.

Some commercial dredgers on the Klamath River have taken this concept one step further by placing the electric or hydraulic winch on the front of their dredge platform. The dredge is directly behind the hole, anyway. This normally requires an extension of the dredge flotation platform in the front to allow for the additional necessary buoyancy. The advantage to this concept is not having to move around two separate platforms. The disadvantage is not being able to pull the boulders far enough to the rear when you are dealing with lots of boulders.

When you are winching from the front of a commercial dredge, it is also important to keep looking up to make sure you don’t pull the front of your dredge entirely underwater!

This can also potentially happen with a floating winch platform, but it is not normally a problem, because the pulling point is generally from the center of the flotation, as opposed to directly off the front of a dredge.

One local innovative dredger recently came up with the idea of mounting a winch on the front of his dredge in a backwards direction. By also mounting a snatch block under the center of his dredge, under the sluice box, then the pulling point of the winch is centered better on the dredge’s flotation platform. This helps eliminate the problem of submerging the forward part of the dredge.

One point to remember is to never tie off the rear of your dredge to a high point on the bank, or to a highline across the river, when you are planning to winch off the front of the dredge. This type of rigging will pull the back end of the dredge up into the air during rock pulling!

The biggest problem we have run into with floating winch platforms is in the electric controls. We have yet to find an underwater control box on the market which is designed for electric winches. So we have had to waterproof the standard control boxes. This is not all that difficult to do, but it is only temporary. Every few weeks, we find ourselves taking the box apart, and having to rework it.

There is also a potential safety hazard with the electric winches, in that if the controls short-out underwater, the winch can simply start winching! We have learned to create a quick disconnect on the electric cord near the control box. If we lose control of the box, we can unplug it, and the winch will shut down.

One important safety note on this: If you create a safety quick connect using extension cord plugs of some kind, make sure you put the female-side on the power cord. This way, the power cannot be shorted across once the cord has been unplugged. This lesson was learned locally the hard way when a dredger unplugged the control box and dropped the cord into his aluminum boat. He had the cord rigged with a male fitting. The male posts touched the aluminum of the boat, and he was winching!

While it is not particularly difficult to do, it is a bit involved to waterproof the control box to an electric winch—too involved to go into in this article. We use a fifty-foot #14 extension cord; we use a product called Dip-it, and we do a few other things to avoid making the modification so permanent that we cannot easily get back into it to re-do it when necessary.

The advantage to hydraulic winches is in having no problems with the control box. No electricity! This is why I believe the best future platforms will be utilizing hydraulics. For dredge platforms, it is not too difficult to mount a hydraulic pump directly to the dredge motor.

I hope this information has been of as much help to you as it has been to us dredgers up on the Klamath River.

 

By Dave McCracken

“Dredging for Diamonds and Gold During the Rainy Season…”

Dave Mack

 

Author’s note: This story is dedicated to Alan Norton (“Alley”), the lead underwater mining specialist who participated in this project. Under near-impossible conditions, Alan made half of the key dives which enabled us to make this a very successful venture.
There are very few people I know, if any, with more courage, dedication and enthusiasm to successfully complete a difficult mission, than Alan.

If I can make it go right, I try and go overseas at least once or twice a year, usually during our winter months in California, to participate in some kind of a gold mining or treasure hunting adventure. Sometimes I am paid as a consultant to do preliminary evaluations for other companies. Sometimes I just go on my own. Doing these projects in remote and exotic locations is kind of like going back into time, or like going into a different universe. It is always a great adventure! Sometimes, on these different projects, everything goes smooth and easy. Sometimes we uncover fantastic riches. Sometimes we find nothing at all of great value. And, once in awhile, conditions are extraordinarily terrible and put all of our capability and courage to the final test. Such was the case on our recent testing project into the deep, dangerous jungles of southern Venezuela.

Venezuela lies on the north coast of South America along the Caribbean Sea. It is a South American country that ranks as one of the world’s leading producers and exporters of petroleum. Before its petroleum industry began to boom during the 1920′s, Venezuela was one of the poorer countries in South America. The economy was based on agricultural products, such as cocoa and coffee. Since the 1920′s, however, Venezuela has become one of the wealthiest and most rapidly changing countries on the continent. Income from petroleum exports has enabled Venezuela to carry out huge industrial development and modernization programs.

Columbus was the first European explorer to reach Venezuela. In 1498, Columbus landed on the Paria Peninsula. In 1498 and 1499, the Spanish explored most of the Caribbean coast of South America, and Spanish settlers were soon to follow the explorers.*

Almost all Venezuelans speak Spanish, the country’s official language. Indians in remote areas speak various tribal languages.*

I personally was contacted by an American investment group that was in partnership with a Venezuelan mining company. They hired me to spend around thirty days doing a preliminary testing evaluation on a concession (mining property) the company owns in the deep jungles of southern Venezuela. The property was reported to contain volume-amounts of gold and gem-quality diamonds. A river flows across the concession for approximately twenty-five miles.

The company had purchased a 6-inch dredge along with the support equipment. They wanted me to complete a dredge sampling program to see what kind of recovery we could obtain from the river. I brought one other experienced dredger along by the name of Alan Norton. Alan and I had spent several seasons dredging together on the Klamath River in northern California, and I had learned years ago to always bring at least one very capable teammate along when doing diving operations in the jungle environment. This proved to be a really wise decision!

We flew into Caracas, which is the capital of Venezuela, a very nice, modern city with big office buildings and hotels creating a beautiful skyline. Caracas enjoys the reputation of having one of the best night-lives in the world. Poverty is also visible along the outskirts of the city where thousands of people live in small shacks called Ranchos.

The company put us up in the Caracas Hilton where we spent a comfortable night, only to fly out the following morning to Ciudad Bolivar–which is a fairly large city, and the diamond capital of Venezuela.

Upon arriving in Ciudad Bolivar, we were promptly met by representatives of the company, along with the company’s bush boss, an American adventurer by the name of Sam Speerstra. Sam would make a good match for Indiana Jones. It was quickly apparent that he loved danger by the way he drove us through traffic to the small landing strip that we were to shortly depart from on our way to the concession. Sam had us unpack our bags while he arranged to have the aircraft pushed out onto the runway by a half dozen or so airport workers.

The dual engine aircraft was not in the best state of repair. The engine shrouds were held on with bailing wire, some of the cargo doors were held together with duct tape, and the instrument panel was held in place with safety pins, some which were not holding very well.

Sam enjoyed my apprehensive observations of the plane while our baggage was being loaded. Proudly, he told me the aircraft company we were using had the best record of non-accidents in the whole country. However, he also said the landing strip on the concession was quite small and hard to get into because of a large hill that had to be dropped over quickly in order to touch down at the beginning of the runway. In fact, he informed me the company had lost one of its planes trying to land on the concession during the week before. I asked if anyone was hurt. “All dead,” Sam responded, with a smile on his face. And he was serious! .

While, for proprietary reasons, I am not able to divulge the exact location where we were operating, I can say that we were at least several hundred miles into the jungle south of Ciudad Bolivar, towards the Brazilian border.

In this instance, we were asked to do this preliminary evaluation just as the rainy season was getting started. Shortly after taking off in the dual engine plane, we began seeing large rolling clouds. The further south we flew; the larger and more dense the clouds became.

About halfway to our destination, the pilot put down on a small landing strip in a relatively small village to pick up a full load of mining equipment which he had to leave there the day before. He had not been able to get out to the concession because of the almost zero visibility caused by the heavy rains and clouds. As we landed on this strip, the first thing we noticed was a completely wrecked plane that had crashed there. This added to our apprehension and to Sam’s sense of adventure.

It took about an hour to pack the airplane completely full of mining equipment. Since we had to remove the seats to make room for gear, Alley and I were directed to lay up on top of the gear that was stacked up in the belly of the plane. No seat belts! And the plane was loaded so heavily, even the pilot was not sure whether or not we were going to make it off the runway when we took off. We barely made it, and the plane was very sluggish to fly for the remainder of that trip.

We were in and out of clouds for the remainder of the flight, much of the time with zero visibility outside of the airplane. Occasionally, we would break through the clouds and see nothing but dense jungle below us as far as the eye could see in any direction. This was the Amazon! Sam took the time to educate us on the many different types of animals and insects which would certainly devour us if we were to have the bad fortune of crashing. Tigers and jaguars, driven out of some areas by villagers, only to be more hungry and ferocious in other areas. Six-foot long electric eels, called Trembladores by the natives, capable of electrocuting a man with 440 volts, and man-eating piranha were all through the rivers and streams, according to Sam. He told us of bushmaster snakes, the most dreaded vipers in all of South America. Sam said he personally had seen them up to twelve feet in length with a head about the size of a football. “Very aggressive–they have been known to chase a man down.” Sam said you could see the venom squirting out of the fangs even as the snake started to make a strike– one of the most horrifying experiences he had ever seen. “But, not to worry, I brought along a shotgun just in case we get in trouble,” Sam told us as hundreds of miles of jungle passed beneath us.

After quite some time, at a point when the clouds cleared away just long enough to see, Sam pointed down to a short runway cut out of the jungle. At first, we could not believe we truly were going to try and land there. Sure enough, it was the base camp for the concession. We made one low pass over it. The base camp looked large and well equipped. There was also a small local village right near the base camp. The landing strip was filled with puddles and looked to be mostly mud. Alley and I were a little nervous after Sam’s big buildup, and we had very good reason to be nervous.

In order to land on the strip properly, the pilot had to fly just over the treetops, around a ridge, to drop quickly over a hill almost into a dive to get low enough, fast enough, to meet the beginning of the runway. The pilot’s skill was very good, although it is the only time in my life I have ever been in a plane that actually tapped the tops of trees as it was going in for a landing. The thump, thump of the trees hitting the wheels of the plane put me in somewhat of a panic. But it was all for nothing, because within seconds we were safely down on the runway. The pilot and Sam seemed to think nothing of the hair-raising landing experience. Alley and I felt like cheering that we were still alive. This was the mental state we were in when we arrived in the jungle. And it was just the beginning!

Local villagers came out to help us unload the plane. They all seemed like very nice people. After having a chance to load our gear into the bungalow, Sam gave us a short tour of the base camp. The whole area was fenced in. There were numerous screened-in bungalows for the various crew member sleeping quarters, a large kitchen, an office, and a large screened-in workshop area. The company had spent a lot of money getting it all set up. There was a jeep and two off-road motorcycles—all in a poor state of repair. They operated, but without any brakes.

After we had a chance to relax a bit, Sam insisted we go meet the “Capitan,” who was the chief of the local village. We had to arrange for several boats and a small group of local Indians to support our operation along the river. Sam explained to us that public relations were very important and that we must go over and have a friendly drink with the Capitan. We assumed Sam was bringing the Capitan a bottle of Scotch or Brandy or something as a gift. But that’s not the way it happened. Sam preferred to drink the local mild alcoholic beverage called Cochili. This drink is made by the local Indians from squeezing the juice out of a special plant that they grow. The juice is allowed to ferment in the open air for several days or weeks, depending upon the weather. It is a milky white-like substance with clumps of bread-like soggy goo (kind of like pollywog eggs), along with some greenish-brown mold mixed in–it was great to behold! It smelled almost as bad as it looked.

We met the chief, who looked totally wasted on something–probably the Cochili drink. And immediately upon our arrival, the chief ordered some children to bring glasses and drink for everyone. Promptly, our glasses were filled to the rims. Sam quickly downed his first glass, licked his lips, smiled and said, “This is all in the name of good local public relations!” To be polite, I downed half my glass and did my best to choke back my gag. The stuff tasted terrible! I realized my mistake right away when one of the kids immediately took my glass and refilled it to the brim. Alley was paying close attention and slowly sipped his drink, and I followed suit. There was no place to spit if out without being seen, so we had to drink it down. Sam put down three or four more glasses and shortly was slurring his Spanish in final negotiations with the chief. I’m not really sure they understood each other concerning any of the details, but everyone seemed happy with the negotiation.

It was a good thing that the rainy season prevented the remainder of our mining equipment to arrive in the jungle for the next two days. Because I spent the next few days with a severe case of the jungle blues. I was popping Lomotil tablets left and right to try and dry up my system and finally started making progress on the third day in the jungle. Man was I sick!

Alan boasted that he never had a case of diarrhea in his life and that he never would. Sam spent several hours every evening drinking Cochili with the local Indians who would accompany us into the jungle. He was getting to know them better.

The weather was hot and muggy, although the heavy rains had not started yet in earnest. The jungle was alive, especially at night when the jungle noises were almost deafening. It was certainly not a nice place to go for a friendly, evening hike. We were glad for the fence that surrounded the compound.

On the third day, still weak from the fever, but feeling like I should be productive at something, I decided to take a motorcycle ride on the new jeep trail which had recently been hand-cut several miles to the river. Why is it that I always know when I am going to come upon a nasty snake just an instant before I see it? As I rounded the first corner on the trail, a large viper took off ahead of me up the trail faster than a man could run. No brakes! Finally, I stopped the bike, turned around, and returned to camp to rest up some more.

“Once the rains started, the water was so muddy we had zero visibility underwater and had to find our way through the broken branches of submerged trees by feel”

The remainder of our gear finally arrived on the following day. We assembled everything to make sure it was all there. It wasn’t. We were missing the assembly bolts for the six-inch dredge; we had only one weight belt; and we had no air reserve tank for the hookah system! This was not good!

We finally ended up using bailing wire to hold the dredge together, and had to settle for hooking the airline directly to the dredge’s air compressor. One weight belt was all we were going to get—not much margin for error! The entire operation would depend upon us not losing that single weight belt.

On the following day, all the equipment was packed to the river by the local villagers. This was not an easy two-mile pack, because the trail was very muddy and was quite steep up and down the whole distance. Alan and I were using one of the motorcycles to get up and down the trail, which was a real adventure with no brakes.

One very interesting thing about this jungle is that huge trees, for no apparent reason at all, come crashing down. At least several times a day, we would hear huge trees crashing down in a deafening roar. On one occasion, Alan and I were returning to base camp on the jeep trail. We had just come up that trail fifteen minutes before. As we were going down a muddy hill and rounding a bend, we ran smack right into a huge tree which had just fallen across the trail. Good thing I was driving! We smashed into the tree with both of us flying off the bike. Luckily, neither of us were hurt more than just a few bumps and bruises, although the front-end of the motorcycle was damaged. Chalk up one more for the jungle.

During the time while equipment was being transferred to the river and set up, we took several airplane rides to survey the section of river which we were planning to sample, and to make arrangements at a small village (with a landing strip) about twenty-five miles downstream to obtain fuel and some basic supplies as needed during our sampling trip. Once we started, we would not be in contact with the base camp until our sampling project was complete–which was to be about twenty-five to thirty days later. In flying around the area and landing on the two strips, it soon became apparent that the pilot was very skilled. While he definitely was flying by the seat of his pants, the conditions were normal and it was no big thing (to him). Sam just had the advantage of prior experiences at the concession and was psyching us out–all in fun. It only took a little while to catch onto his game.

One of the things we quickly learned in the South American jungle, is that you never stand still for more than just a few seconds. Otherwise, a steady line of ants, mites, and other meat-eating critters will crawl up your legs, inside or outside your pants, and go to work on you. We had plenty of mite bites–which hurt, itch, and generally drive you crazy for about five or six days before they start healing. And, we learned to never brush up against bushes as long as we could help it, for fear of getting fire ants all over us. They sting like crazy!

We never allowed our bare skin (especially bare feet) to come in contact with the bare ground in or around the camps. This is because of chiggers. Ants were everywhere. Whole armies of big ants could be seen to follow a single file line up and down the trail for a mile or more, carrying torn up leaves from a tree which was actively being stripped clean by other ants. The whole jungle was crawling with life. Every square inch had some creature that was starving to take a good bite out of us. Perhaps it was the muggy weather, or maybe weakness from the jungle fever, but my first impression of the South American jungle was that it was doing everything it could to suck the life energy out of my body.

On more than one occasion, some huge animal would go crashing through the jungle just a short distance from where we were standing. We never saw the animals, but had the continuous feeling that some huge cat or wild boar was ready to come smashing in on us. And, of course, the shotgun was never in my own hands when this occurred, which was probably a good thing for everyone else in the vicinity.

“We allowed the natives to swim in the river first to make sure there were not going to be problems with piranha and Trembladores”

While we were packing gear, one of the village-helpers came running in to show off a bird spider he had caught and skewered on the end of his machete. This spider was bigger than my hand; it looked like a huge tarantula. According to the natives, these fearsome spiders catch birds to feed on, not flies, in their webs.

Our first few days on the river were absolutely, breathtakingly, exotically beautiful. The sun came out. The river was low and semi-clear. The water was warm, but just cool enough to give us satisfaction from the muggy air temperatures. We did not need wetsuits other than to protect our bodies from scrapes and bruises. We dredged a half dozen or so easy sample holes. Gravel was shallow to bedrock. The first camp was quite comfortable. The Indians were using their bows and extra long arrows to catch great-tasting fish. Everything was perfect. I remember wondering why I had such a problem adapting to the jungle in the first place. It was like paradise on the river, and we were even getting paid to be there!

We allowed the natives to swim in the river first, to make sure there were not going to be problems with piranha and Trembladores. This is not a bad thing to do. We did not make them swim first. They simply dove in. We always watch for this in a jungle environment. The local Indians know what it is safe to do. After watching the Indians swim for quite some time, we decided it was safe.

The natives live under grass roof shelters–often with no sides. They hang hammocks from the supporting roof beams and sleep at least several feet off the ground. Since Ally and I don’t sleep very well in hammocks, we brought along cots, instead. On our first night in the jungle, Sam insisted the cots would be just fine on the ground. They had short legs which put the cots about six inches off the ground. Alan and I both had sleeping bags which could be zipped up. Sam simply had one dirty white sheet. About midway through the night, Sam’s cot collapsed on him. Shortly thereafter, he was dancing around the camp yelling, “Fleas!” He was barefooted, and the natives spent the next two weeks picking chigger eggs out of the bottom of his feet with sharp pointed sticks.

Let me explain chigger eggs: These critters somehow lay eggs inside the pores of your skin. The eggs grow larger and larger, causing an open sore. It keeps getting worse until you realize it is not just a mite bite. The egg has to be removed with a sharp piece of wood, kind of like a toothpick. The eggs I saw were about the size of a soft, white BB when removed. It was explained that this was really a sack full of eggs. The trick was to get rid of them before the sack broke. Otherwise, the problem was severely compounded. Apparently, the dogs carried these chiggers all over themselves. We were instructed to not pat the dogs for this reason. It was a good lesson for us, and we learned it quickly from Sam’s experience.

We had a three hundred-foot roll of half-inch nylon rope with us for the mining operation. The following day, Alley and I allocated one hundred and fifty feet of that rope to be used to tie our cots up into the shelter beams to keep us well away from the ground. Our Indian guides were quite amused by this. The rest of the rope was used in the dredging operation.

On about the fourth day on the river, Sam returned to the base camp to supervise the other surface digging testing operations. Our cook became extremely angry soon after Sam left. I later found out that he was contracted by Sam to spend only five days in the jungle. Sam left without taking him along. He was stuck with us in the jungle for the next twenty days or so, and we all paid for his anger in the food he prepared for us. We would get fresh-made pan-fried bread every morning that was so saturated with oil that you could squeeze the oil out of it in your hand. This, along with a can of sardines for breakfast. We got leftover bread from breakfast for lunch, along with more sardines. We also got sardines with stale bread for dinner. The cook was basically on strike. Luckily, there were plenty of banana and mango trees along the river to supplement our diet.

“It was easy to follow the tributary because it was running straight black mud”

But we had our attention on other matters. The heavy rains began on the day Sam departed. In one night, the river rose up at least fifteen feet. And it roared! Entire trees were washing downriver. It was a torrent. The water was the color of brown mud. The river rose up and spread out into the jungle, making the whole area into a huge, forested lake. There were no riverbanks to be found in most areas. Our own camp was within four feet of being washed away. We knew where the river was only because of the swift moving water. Some of the river was difficult to travel upon, because it was flowing through the treetop canopy, which was occupied here and there by huge nests of African killer bees and other hornets and varmints. It was a nightmare!

On top of that, the natives caught a hundred-pound Cayman (alligator) with a net out of one of our dredge holes where they had been fishing. It was certainly big enough to take a man’s arm off. At that point, the natives told us these animals came much larger on the river.

That was the day Alley decided to come down with his own bout of jungle fever.

Since Alley was incapacitated, I chose that day to hike back to the base camp and have a talk with Sam about the adverse diving conditions. Although we had recovered some diamonds and gold already, I was not comfortable with the recovery system for diamond recovery. I also was not excited about diving in the swollen, muddy river. I would like to get a look at what is going to eat me before I die! Even the natives, who were standing in line to dive in the clear water, absolutely refused to dive in the river once the rains started. This was definitely a very bad sign. Sam managed to get the big boss on the radio and I explained the problems to him. In turn, he told me that his entire company was depending upon the results of my sampling project to justify further investment in the project once the rainy season tapered off. “It all depends on you, Dave.” I told him we would do the best that we could.

The next day, Alan was so weak from diarrhea, that he was barely able to get out of his cot to do his duty outside of camp. I felt my own duty was to go do some sampling with the help of two natives as my tenders. Rather than dredge on the main river (which was raging), I decided to test one of the main tributaries which had the reputation of having lots of diamonds. The natives left me to keep an eye on the dredge, which was tied to the canopy of some trees at the mouth of this tributary, while they hacked a trail through the tree branches several hundred yards up this creek–which was now an endless lake out into the jungle. It took several hours for them to make the trail with their machetes. It was easy to follow the tributary because it was flowing straight, black mud, compared to the brown color of the river water.

While I was standing on the dredge waiting for the natives to finish the trail, a huge bee buzzed by my head. Within a couple minutes, there were about a dozen of these bees buzzing me. They were really mean! I had my hat off and was flailing around wildly trying to keep them away. There was no place I could go off to, to get away from them. Finally, I had to jump into the water and hide underneath the sluice box. This is where the natives found me when they returned. They were quite amused.

It took quite some time for us to drag the dredge up this tributary, because the branches were just hacked off at water level. I was looking for a place we could work off of a streambank, but eventually gave up on that idea. The water was simply too deep. I ended up throwing the suction hose over the side of the dredge, primed and started the pump, put on my seventy-pound lead weight belt and other diving gear, crawled over the side and shimmied carefully down the thirty-foot suction hose. The problem was feeling my way down through the submerged tree limbs to find bottom. There were logs and branches everywhere. I was in total darkness–complete zero visibility. Everything was done by feel, sensation and yes, fear. I finally found the bottom and estimated it to be about twenty-five feet deep by the amount of suction hose I had remaining with me on the bottom. It was scary down there!

After seeing the Cayman on the day before, I had visions of being grabbed by a huge alligator, and other visions of being grabbed by a huge python. A strong voice from inside my heart was telling me to end the dive. It was too darn dangerous! Any emergency would have me and my airline all tangled in the branches. Having to dump the weight belt would put an end to the entire program, because we only had one weight belt.

I decided that I should complete the sample after all we had gone through to get me on the bottom. This is what I was being paid to do.

As I dredged into the gravels on the bottom, by feel, I discovered more buried branches and logs. These, I simply tossed behind me just like I do with oversized rocks. I got into a pretty steady routine down there and was making good progress. But the strong picture of huge alligators and pythons was right there with me all the time. Do you know the feeling you have when watching a scary movie when you know something terrible is just about to happen? And when it happens suddenly it scares the heck out of you? This was the state I was in when something heavy jumped onto my back. I let go of the hose, turned on my back, and kicked this thing off of me like a crazy man–like I was fighting off an alligator. Then I realized it was just one of the water-logged heavy pieces of wood I had thrown behind me.

This was a terrible feeling of terror and embarrassment. I’m serious; I was so scared, I wanted to crawl right back up into my mother’s womb. I was left wondering what the heck I was doing there. Why was I doing this? It was nuts!

It is impossibly-difficult times like this, and how you manage them, that contribute to the definition of your personal character and integrity. And I freely admit that staying down there to finish the sample was one of the most difficult challenges I have ever overcome. This was a total mission-impossible situation! After a moment to get myself refocused, I turned around and finished the sample hole to bedrock. I carefully shimmied back up the suction hose, coiling my airline as I went, to make sure it was not tangled in branches. When we cleaned up the sluice boxes, we were rewarded with several gem-quality diamonds, one which was quite large and handsome.

“I let go of the hose, turned on my back, and kicked this thing off of me like a crazy man!”

When I got back to camp that night, Alan was still sick in his cot. I did not hesitate to tell him of my experience. I also told him he was doing half the diving from then on, starting the next day, with or without jungle fever!

And that’s the way it went for the next twenty days or so. We completed four samples per day, with Alan doing half of the diving. Some days, the river was so high we had to tie off on branches of trees out in the middle of the river. We would take turns watching for trees being washed down the river, and would pull each other out by the airline every time this occurred, to keep from getting snagged by the trees and dragged down river.

The diving was extremely dangerous. Each time one of us went down, we did so knowing there was a definite possibility that we would not live through it. The only other option was to give up. But, we had originally agreed to do our best to overcome the difficult conditions. That’s how we got the job in the first place. We didn’t really have any other choice. I look back on it now and can enjoy the adventure. At the time, however, it was not any fun at all. It was crazy!

The biggest problem was the lack of an air reserve tank on the dredge. Sometimes it would take as much as ten minutes to feel a way down through the submerged branches in the total darkness. We had to find a path. There was no easy, fast way to get back to the surface. Cutting the weight belt loose would probably be sure death. Not only that, but we would probably never recover the body! No reserve air tank meant almost no margin should the engine quit for any reason–which, luckily, it never did.

However, the heat from the compressor did melt the airline, causing it to blow off altogether when I was down on one dive. We run the airline around our neck and through our belt for safety. With no air reserve tank, we were able to hear the compressor working underwater by the vibrational sounds coming from the airline. I had just spent quite some time finding a path to the river bottom and started dredging gravel, when my air supply was abruptly cut off and I no longer heard the compressor noise from the airline. But the nozzle was still sucking. I stayed there for a few seconds trying to understand the problem and what to do, when suddenly my air supply returned and I heard the compressor noise again. I almost just kept on dredging, but decided after all to go up and see what had happened. When I got to the surface, Alan was holding the airline onto the compressor output with his bare hand. He got a pretty good burn out of it. An inexperienced underwater miner never would have known what to do. Alley saved my life. This is one of the reasons I seldom do these projects alone.

“He made his bow out of the core of a hardwood tree, using a machete to carve it exactly the way he wanted”

As we progressed with our sampling further down the river, the natives would move all the gear to new camps every three or four days. Some camps would be reconstructed out of already-existing structures. Other camps had to be built from scratch, using plastic sheeting for the roofing material.

Our main native guide was named Emilio. He was a real jungle man in every sense of the word. He walked with a limp because of an earlier airplane crash in which he was the sole survivor. His family hut had been hit by lightning several years before, and everyone in the hut was killed except Emilio. He was a real survivor! One night, he went hunting with our shotgun–which was only loaded with a single round of light bird shot. In the darkness of the jungle at three o’clock in the morning, Emilio snuck right up on a five-hundred pound female wild boar and shot it dead–right in the head. We had good meat for several days, and even the disgruntled cook cooperated with some excellent meals.

Emilio taught us how to hunt with bow and arrows–mainly for fish. But, he was able to bring in a few chicken-like birds on several occasions. The meat was tough and stringy, but that was probably because of the cook. He made his bow out of the core of a hardwood tree, using a machete to carve it exactly the way he wanted. The arrows were made from the same hard material, using poison from snake venom on the tips for big game hunting. The natives did not have any modem weapons whatsoever, other than the shotgun we let them use while we were there.

Even Emilio refused to dive during the rains. And, our doing so considerably raised the natives’ evaluation of our physical abilities and bravery, even if we were greenhorns in the way of the jungle.

Each Indian we met was very skilled and uncanny in jungle survival. They could tell a boat was coming up the river three hours before it arrived by hearing the change in bird sounds. You will never find a harder bunch of workers anywhere.

The canoes we used were also carved
out of the trunks of hardwood trees. A skilled native takes about six months to make a good dugout canoe, which sells for about sixty dollars. Mostly, the canoes are paddled. But the more affluent natives do have outboard motors, which make the canoes go along at a pretty good clip. The natives are very skilled at driving the

canoes over top of submerged logs and through rapids. A lot of the time the boats were loaded so heavily that there was only about a half-inch of freeboard on each side. Yet, we never swamped a boat.

The gold pans they used, called Beteas, are also carved out of huge logs. Several classifications of screens are used on top of the Beteas to classify material and screen for diamonds. The natives have a special way to quickly rotate the screens, which causes diamonds to move to the center of the screen where they are easily picked out. It is quite something to watch.

Many native miners only go after the diamonds. They know they only need to find about one or two diamonds a year to make it worth their while for the extra things they want. Otherwise, the jungle provides for all of the basic survival needs of the natives. They are quite self sufficient.

“I was running down the trail at full speed like a mad man out of control, swinging my hat about

The natives received about two dollars a day in wages and were happy to get it up until the end of our project. We wanted to extend one more week to really finish the job right. However, the natives made it clear that no amount of money could sway them from going back to harvest their gardens on time.

While we were hauling our gear along the mile and a half-long trail to the landing strip, I was swarmed by African killer bees. It was terrifying! I heard them coming from quite some distance away. It sounded like a bus coming through the jungle. First, there were only a few bees around me, then a whole bunch. In panic, I was running down the trail at full speed like a mad man out of control, swinging my hat about. Then they were gone. I put my hat back on only to get stung right on top of the head. I felt completely spent. It was time to go home.

When we returned to the base camp, we found out Sam had plenty of problems of his own. At least half his sampling crew had to be evacuated from the jungle due to an outbreak of malaria and yellow fever. When we arrived, he immediately needed our help to Griphoist the jeep out of a creek that it had crashed into. Apparently, the jeep had a problem jumping out of first gear while being driven down a hill. The lower gears needed to be used to keep the jeep from going too fast, because of the no-brakes situation. Sam was driving the jeep down a steep hill with four natives in the back. It popped out of gear and they made one mad roller-coaster ride to the bottom, only to smash right through their man-made bridge into the creek. Miraculously, no one was hurt and the jeep wasn’t wrecked. We managed to get the jeep back onto the trail and hightail it back to the base camp just as total darkness descended on the jungle. Sam looked at it as just another great adventure; just another day in the life of a jungle-man!

Our trip back from the jungle to Caracas was relatively uneventful, except that I was able to buy a nicely-cut diamond in Cuidad Bolivar for pennies on the dollar at U.S. prices. I presented this to my (ex) wife when I returned home and she was quite pleased to have it mounted on a ring.

Over all, our project was successful. We found diamonds, and we found some gold. We did exceptionally well considering the impossible conditions. The largest diamond located on the concession while we were there was over eight carats. But that came out of one of the test pits on Sam’s digging operation. We never found gravels deeper than three feet to bedrock, and there was very little oversized material to move by hand–other than submerged logs. The area would be a breeze to work in clear, slower water–like during the dry season. Everyone involved was impressed with our test results. We submitted a proposal to do a more extensive test/production project with more men and larger equipment, but internal politics within the company ultimately killed the program altogether.

I’ll say this: If we ever do go back, I guarantee it will not be during the rainy season. And we will have a cook who can find no better pleasure in life than to feed us well.

* The World Book Encyclopedia, 1987 Edition.

 

 

 

By James B. Wright

Learning to interpret sound anomalies on your metal detector.

 

Noise comes to those who would use an electronic metal detector in three different basic forms:
1) Locally generated sounds (such as motors, river rapids, people talking, etc.).

2) Equipment-generated sounds (whistles, squawks, buzzes, etc., from equipment maladjustment or defects).

3) And a third noise, which is the sound of a good piece of equipment operating the way it should.

The counter-measures which must be taken against the first two types of noises should be obvious. Kill the engine, stop the talking or wear headphones which prevent outside noises from entering the ear. And, of course, adjust the equipment properly, or have it fixed, and learn to adjust it properly.

The third type of noise is the good type. It is the noise that is created when a good instrument is set up right and working most-efficiently. This noise is a “frying” sound, kind of like rain on a quiet lake, the wind through the pines, a gentle rapid on the river or a crowd at a ball game. It is a good, clean steady hiss. On a meter, it may be a steady deflection of 25-40% of full-scale.

Unfortunately, you cannot have sensitivity without this type of noise, simply because noise is built into all physical processes and all of nature.

What is “noise” as used in this context? One good example is the sound you get from your television set when it is tuned to an unused UHF channel. This is when you see snow on the TV screen. What you are seeing and hearing is the composite of a large number of random electrical impulses, all continuously being generated by the very atoms which make up the television, as well as those which make up the earth, the atmosphere, the sun and the rest of the cosmos. This is the sound of Nature doing her thing!

So, what’s the point of all this?

When you send a signal into the ground and try to detect a response from bits of gold, or from other types of deeply-buried chunks of metal, you are usually dealing with a very weak return-signal amid a sea of pre-existing natural “noise.” The detector must identify and amplify the desired signal and try to discriminate against the unwanted noise.

This is where the user becomes a part of the detection system. Because human hearing is able to pick out signals buried in noise better than any piece of electronic gear (except for certain radar equipment which is gawdawful expensive).

Why then must we not only tolerate noise but appreciate it? Because, if your equipment is so sensitive that it will sense the intrinsic “noise” of Nature, it will sense an equally-weak signal from your target. If your detector sounds-off on hot rocks or black sands, it is alive and well and doing its job.

Your job is to learn to hear and interpret the anomalies in the noise, the “whisper” that is just slightly different, the smallest change in the pitch of tone.

This is what weeds out the expert from the rest of the pack. He (or she) is like a good sonar-man, picking out the submarine while ignoring the chatter of the whales, the fish and the other noises of the sea.

 

By Dave McCracken

Sometimes, you will find that you are as close to winning as you can be, even though things have never looked worse!

Dave Mack
 
A short time ago, my dredging partner and I were sampling in a new section of river. We were looking for high-grade pay-streaks, dredging test holes, and hadn’t had any luck from five very well-done samples. We floated down to a new section of river, where the water was very fast. It was on the inside of the tail-end of a bend of the river–an excellent place to find a high-grade pay-streak.

The problem was that we hadn’t found a single speck of gold in the previous five sample holes. This was uncommonly-bad! Usually, we at least find some showing of flood-gold in every test hole in river-dredging. For the most part, I had decided that this section of river must have been very low-grade. We had about a half-mile left downriver to the next river access–where we would be able to pull the dredge back out of the river. So, we decided it was worth a few more sample holes as we drifted down in that direction.

This new section of river had slow water towards the bank. I had it figured that the pay-streak would be located out under the fast water — which is often the case. I don’t know why, but mother-nature often has a knack for hiding her natural treasures in areas which are more difficult to get into!

We set up the dredge in the slower water alongside the bank, got everything running, and I started the sample hole right out on the edge of the fast water. Once the hole was down far enough to protect me from the current, I pushed the hole out under the fast water where I figured the pay-streak would most likely be. This was very difficult, because the force of water was pushing very hard against the suction hose and my airline. I just muscled the work through against the current, but it took a great deal of effort. I was in that zone where heavy effort, physical pain, and emotional stress are all the same?

The suction hose was swept back into the current several times, which required me to go back, drag the hose over towards the bank, pull it back upstream, and get it back out into the sample hole. All this, to keep pushing the hole further out into the current, and deeper towards bedrock.

When I reached bedrock, I uncovered it slowly to see if there was any visible gold in the cracks. All I saw was a few small flecks–nothing to get excited about. It was gold, however; and seeing it on the bedrock was encouraging. It was the first gold we had seen in that section of river. Seeing the flecks on the bedrock meant that I was beginning to dial into the right wavelength!

Having it in mind that the best gold would be further out into the current, I pushed the hole in that direction. The further I pushed, the more difficult it was. The bedrock out there showed no gold. My arms felt like spaghetti!

So I pulled back into the original place where I spotted the gold flecks on bedrock, took another small cut off the front of the hole, and worked it down to bedrock slowly so I could see if there was anymore gold. I did not see any. So I assumed this area must also be low-grade and decided to call it quits.

As I was dragging the dredge’s suction hose in towards the bank, the thought crossed my mind that I ought to test the inside of the dredge hole–over towards the slow water.

If the streambed material had been deeper, it is likely I would not have tested toward the inside. Why? Because I had it in my mind that the pay-streak was out under the fast water; not under the slow water. But, because the streambed was shallow, and I had seen some gold on the bedrock where I first touched down, I decided to take a quick cut off the inside of the sample hole.

Sure enough, I spotted several small flakes of gold on the bedrock. So I took a larger cut off the inside, pushing towards the bank. About halfway down to bedrock, I started seeing flakes of gold in the gravel–kind of like Christmas. On the bedrock, I uncovered a pothole full of gold; it was about eight ounces in all–about half of it was jewelry gold. And that began one of the richest pay-streaks we ever found!

There is a lesson in this!

Everything we do, everywhere we go, is the result of the decisions we make. Sometimes we get going on a path which is just not the right direction! This is not just in gold mining. Sometimes the signals are there, telling us we are going the wrong way — often by the amount of pain and discomfort and effort it is taking to keep moving in the wrong direction. Have you ever found yourself in a major difficulty — only later, sometimes much later, to realize that it was one of the best things that ever happened to you?

The lesson is to never give up hope! Never say die! Sometimes, you will find that you are as close to winning as you can be, even though things have never looked worse. This is especially true in gold mining.

This is not to say that you should keep pushing hard in a direction that is not working. It is to say that if one direction does not seem to work, take it a little further, and then look around for another way to go. Don’t get fixed in one mind-set. Ask yourself what you are trying to accomplish, and keep your awareness open and your imagination working to find the available opportunities to accomplish your goal.

We manage group gold mining operations in northern California just about every other weekend during the spring, summer and fall months. During these operations, it is my personal responsibility to make sure that silt, sand and gravel are not washed back into the river off the bank from our tailings-water. This requires continuous effort to keep tailings water directed along the natural contours on the land outside of the river. Sometimes I spend a lot of time running up and down the bank trying to stop the water or slow it down. One thing for sure, if you stop the water in one place, pretty soon it is running down the bank somewhere else! Gravity is a force of energy that never stops.

In many ways, this is not dissimilar to a person’s intention to accomplish a goal. Sometimes, we will find our immediate progress slowed down or stopped altogether. But if we maintain our intention, and study the barriers to our progress, we can usually find other ways to make progress. The key is in maintaining the intention, keep pushing along, and having a little patience.

The best things in life usually take a little time to accomplish. And the best memories often come from the accomplishment of difficult goals.