By Dave McCracken

It is common to find rich gold deposits in shallow streambed material out under the fast water where nobody has ever ventured before!

Dave Mack

Something we have known for quite some time is that pay-streaks, often very rich pay-streaks, exist in the fast water.

At first, this may seem contra­dictory to our general understanding that high-grade gold deposits form in areas of the waterway where the water slows down. However, we must keep in mind that pay-streaks are created during major floods. During a major flood, a sudden drop in the bedrock can cause a very good gold trap, like the riffles in a sluice box, but on a very large scale.

If you turn on a garden hose at slow speed, the fast-water area is found directly where the water flows out of the hose. But when you turn the water-pressure up, momentum forces the water farther out. This condition also occurs within the river during a major flood. Areas where the water runs fast during low-water periods are likely to be drop-zones for gold during high water. The heavy momentum/velocity area will be forced farther downstream, leaving a drop-zone for gold just below the bedrock drop. This explains why you can often find pay-streaks under rapids when the river is flowing at low-water levels. It also explains why you seldom find pay-streaks within the first slow-water area below a set of rapids when the river is running at low levels.

Another reason why you are likely to find gold in fast water is because dredging in fast water is more difficult. Therefore, others are less likely to have mined there before you – including the old-timers. For this reason, fast-water areas can often be virgin territory — meaning places where the original streambed material remains in place from thousands of years of natural geologic activity.

  

What exactly is “fast water?” This depends upon each individual person’s viewpoint. It is primarily a matter of the diver’s comfort level. To some people, if the water is moving at all, it is already too fast to dredge. Other dredgers are able to dredge in water moving so fast that the air bubbles created by the turbulence eliminate all visibility. After diving in really turbulent water, a person’s equilibrium can become so disoriented that he/she can hardly stand up without weaving around, as if intoxicated.

Several years ago, a friend and I were operating a five-inch dredge in some very fast, shallow water. Because of the extreme turbulence, one of us would work the nozzle, while the other would hold onto the dredge to keep it from flipping over. The water was so swift that my friend was swept out of the dredge hole time after time. Once, he was carried away so fast, he didn’t have time to untangle himself from his air line before he reached the end of it. The air line was tangled around his neck! There he was, flopping around in the current, like a flag snapping in a stiff breeze, tethered by the air line around his neck and struggling, unsuccessfully, to regain his footing in three feet of water. After he got safely to the bank, we both laughed so hard that tears were streaming down our faces. That was emotional stress blowing off. Fifteen minutes later, I was the one bouncing in the current behind the dredge, facing backwards at the end of an air line caught between my legs. Needless to say, my friend thought this was pretty funny, too! Dredging in fast water can be fun and exciting (not to mention the gold you can find). But, you must be aware of and prepared for the dangers involved. There is very little margin for error if you get into a situation that is beyond your ability to manage. We all have our limits!

SAFETY

Notwithstanding all the excitement and gold, safety should always be the most important personal consideration. You are the one out there in the field with the responsibility for using good judgment about what you can safely do, without cutting your margin for error too close. The river does not have any sympathy for people who “get in over their heads.” I’ve known several dredgers who lost their lives by over-stepping their personal safety boundaries. It only takes a single mistake. The rest can happen very quickly. Even I have come close to drowning on more than one occasion! All the gold in the world is not worth dying over!

For the sake of safety, it makes good sense for you to not dredge in water that is faster than you are comfortable with. You will have to decide what that is. It is best to practice first in slower water, to gain experience and confidence.

One important thing you should remember about working underwater: Everything may be calm and under control right now; but five seconds later, you can find yourself in the most life-threatening emergency you have ever experienced! This is even true in slow water. But, fast water gives you less margin for safety if you make an error or anything goes wrong. You should not dredge in fast water if you are unable to control the various problem-situations that could develop. You need to anticipate each problem that could possibly arise and work out your response, in advance.

Contrary to what many people believe, being swept down river by the current is not the major concern. This is a normal-happening in fast-water dredging. As long as you have your mask clear and your regulator in your mouth, being swept down river by the current is generally no big deal. That is, of course, unless you are dredging directly above a set of falls or extremely fast water.

In most cases, the “fast water” you are in is not a steady flow of current. It is usually turbulent, varying in direction and intensity. A swirl can hit you from the side and knock you off balance. Or, sometimes it can even hit you from underneath and lift you out of the dredge-hole and into the faster flow. If you get swept down river in fast water, you usually just need to grab hold of the river bottom and work your way over to the slower water, nearer to the stream bank. This movement is normally best-done by continuing to face upstream, into the current, while you point your head and upper-body towards the river-bottom. That posture will nearly always drive you to the bottom where you can get a handhold on rocks or cobbles to anchor yourself down. Then, you can work your way upstream, through the more slack current near the stream bank, and back out to your work-site again. This is all pretty routine in fast-water dredging.

Getting a hole started is one of the most difficult challenges in fast-water dredging. Once you even get just a small hole started into the surface of the streambed, the suction nozzle in the hole can serve as an anchor to help hold you there against the current. There will also be several cobbles behind you to use as footholds, which also make it easier to hold a position there. After the hole has been expanded to the point where you can get at least part of your body inside, you will find significant relief from the effects of the current’s flow. But, it can sometimes be a real challenge until you do get to that point! At times, you may find it necessary to start your hole in slower water, then gradually work your way out into the faster current.

One of the main concerns when dredging in fast water is having your mask and/or your regulator swept or knocked off your face. This situation is one that can cause a person to panic, especially when both mask (vision) and regulator (air) are lost at the same time.

PANIC

There is not a single a person among us who won’t panic, given the right (wrong) situation. People who say they will never panic under any circumstances are just not facing reality and, obviously, have never come close to drowning. I believe it is better to understand and acknowledge your limitations before you get into trouble. The closer you cut your safety margin on safety issues, the more aware of your limitations you should be. And, the more important it is to plan in advance how you will react to certain types of emergencies. It is already too late to make such plans the moment something bad happens!

For me, it takes a lot of personal discipline to stay under control when an unexpected rush of turbulent water jerks my mask off and drags me, blindly and chaotically, down river. This has happened to me on several occasions. I know that under those circumstances, it would not take much more confusion (e.g., air line getting snagged, my body being banged against something, losing my balance, getting a breath full of water from my regulator, etc…) for me to totally lose control and freak out (panic).

I have worked with several guys who have a higher tolerance from panic in the water than I do. And, I know others who feel panicky as soon as they put their heads underwater, even under perfectly-controlled conditions. We are all different, and we each have our own particular point at which we will panic in different circumstances. Everyone has a limit. These limits can actually change from day-to-day, depending upon what other things are happening in our lives. It is better that we not delude ourselves about this. If you allow yourself to get overly-confident, and continually put yourself into situations that can take you beyond your limit, sooner or later you will almost-certainly find yourself tested in a life or death situation.

Panic is a survival-mechanism that takes over when your mind is convinced that your life is in grave danger. At this point, your animal instincts take charge and deprive your intellect of the ability to reason things out. Panic tells you that there is no time left, that you are literally fighting for life just before unconsciousness. The situation demands that you spend your last/maximum physical effort to remove yourself from the danger that is about to mortally injure you or cause you to lose your life. Panic is a horrible, terrifying, and, sometimes, embarrassing experience that happens when your normal, rational self loses control, and the animal-part of you takes over.

There are milder versions of panic. Someone might “panic” and do something silly or foolish in a business or a personal setting. That is not the type of panic that I am talking about here. I’m talking about the raw physical panic that grips you at the moment you realize you may be at the point of losing your life.

There is always a chance of getting into serious trouble any time you are working under the water. Trouble underwater is serious because humans cannot breathe water. There is no margin. You are either breathing air or you are not. It is an immediate emergency when there is no air. Such emergencies can happen in a split second, any time you are in a dredging environment.

TAKING EXTRA PRECAUTIONS

Other types of underwater vulnerabilities are especially present during fast-water dredging activity. Some of this vulnerability is because it is sometimes necessary to weigh yourself down more-heavily with lead weights to stay on the river bottom. Extra weight is needed to give you the necessary stability and leverage to control the suction hose and nozzle and to move rocks and obstacles out of your way. The demands of dredging activity require divers to be so heavily weighted down, that it is impossible to swim at the surface without first discarding the weights that hold you to the bottom.

One of the most serious dangers to a dredger is the possibility of being pinned to the bottom by a heavy rock or boulder. All of the oversized rocks that cannot be sucked through the dredge nozzle must be moved out of the hole by hand or with the use of winching equipment. When undercutting the streambed, or taking apart the dredge hole, there is the possibility of larger rocks rolling in on top of you. This possibility increases when you are working in turbulent, fast water. The erratic changes in the pressure that the water exerts on the exposed streambed material, inside and around the dredge-hole, can cause boulders to loosen up and roll into the hole. These same boulders, if located in a streambed where the water is running more slowly, might not loosen up the same way, if at all. For this reason, a fast-water dredger must take extra precautions to remove all larger-sized rocks when they are exposed. One of our mottos is: “You have to get the boulders before they have a chance to get you!”

When working in fast water, all of your normal safety precautions, preventative maintenance measures, and common sense instincts must be scrupulously observed. Fast water may be thought of as a liquid flow of energy that is constantly challenging you and your equipment. Murphy’s Law (“anything that can go wrong, will go wrong”) is always at work in fast water. It is hard enough to deal with the things that you cannot anticipate will happen. You will have enough of these as it is. But, if you neglect to take action with respect to those things that you can reasonably expect to go wrong, you will almost certainly fail in your efforts to dredge in fast water. If it is wrong, fix it now, before it gets worse!

 

OPERATIONAL CONSIDERATIONS

My dredging partners and I have found that it is physically possible to dredge in water that is too fast for the safety of our dredge — even the kind of dredge that has been designed for fast water. Therefore, the need to operate in an environment that is safe for your dredge is one of the major limiting factors in fast-water dredging.

Most fast-water dredgers add more flotation to their dredge platforms to give more stability. This can be done in different ways, including additional pontoons, inflated tire inner tubes, PVC pipe material, Styrofoam, etc.

One of the main considerations when adding more flotation to a dredge is to avoid increasing the drag against the current. Additional drag causes problems in two ways:

1) The fast-water current puts more strain on your dredge, frame, and tie-off lines.

2) More importantly, the surface-tension caused by all that additional water dragging around the dredge makes it difficult to work near the dredge when you are in the water (which can be a particular problem when you are trying to knock out plug-ups from the suction hose near the dredge).

Another goal when adding flotation is to keep the floats as narrow as possible. A wide set of floats is more likely to be tossed or dragged around by the turbulent flow of fast water.

Generally, when working in fast water, I try to find a location for the dredge where the water is a bit slower, just next to the fast water where I plan to work. This way, I can enter the river in slower water and work my way out underneath the faster water, adding suction hose as necessary.

Otherwise, if we position the dredge directly in the fast water, it will become necessary for the divers to contend with fast water when entering the water from the dredge. This can be done; but it makes the operation more difficult – especially, when the dredgers need to climb back onto the dredge.

Also, the buildup of cobbles and tailings near the dredge can add to the surface-tension and create an even faster current flow under and around the dredge.

When you are set up with the dredge positioned off to the side in some pocket of slower water, your suction hose will be running perpendicular, at least to some degree, to the flow of the fast water. That much hose exposed broadside to the current creates enormous drag, which can cause the suction hose to kink usually within a foot or so of where it attaches to your power jet. Hose-kinks will cause continuous plug-up problems, so they must be avoided. Therefore, you may find it necessary to disconnect the suction hose and cut off the section that has been kinked. However, you cannot shorten your suction hose very much before you lose the amount of operational flexibility you need for freedom of movement while dredging.

Suction-hose kinks can usually be avoided by setting up a special harness to support the hose in fast water. This is often done by rigging one or two extra ropes down from your main tie-off line. The ropes are fastened to the suction hose at points which will allow the hose to be flexed back by the current, but not to the critical kinking point. You must allow the hose to flex back. It is the bend in the suction hose which allows you the movement to expand the size of your dredge hole.

It is best, when rigging a fast-water harness, to rig it in conjunction with your main dredge tie-off line. This way, the entire dredge and suction-hose harness will move together, as a unit, when you need to move the equipment forward as your dredge-hole progresses.

Suction hose support booms are standard equipment on the commercial Pro-Mack dredges.

Larger and commercial dredges may be equipped with booms, which can be extended out in front and used to secure a suction-hose safety harness. In this manner, when the dredge moves forward, the suction-hose safety harness moves with it, as in the situation above.

Another concern in fast-water dredging is to keep your suction nozzle and hose from being swept out of your dredge hole. Sometimes, the current will put so much drag on the suction hose that it takes all of your strength and energy to get any nozzle-work done at all! In such a case, you can relieve the main strain of the drag by tying a section of the suction hose to a large rock at the rear of the dredge hole or some other anchor point further upstream. When doing this, always leave enough slack in the hose to allow you to move the suction nozzle forward as your dredge-hole progresses. Also, be sure to remember to untie the suction hose from the river-bottom before you move the dredge. Otherwise, you can damage the hose by causing kinks in the middle! If you kink the hose in the middle, you will have to replace the hose!

We have also worked out a way to extend the suction hose, swing it out on a pendulum line, and anchor it in place using a spare weight belt.  This method nearly eliminates all of the hose drag for the person managing the nozzle.

When you take a lunch-break or knock off for the day, you can anchor your hose and nozzle by either piling rocks on the suction nozzle or by tying the nozzle to a large rock in the bottom of the dredge hole. It is not any fun to start a production-dive by having to work against the current to get your suction hose back up into your dredge hole, because the fast water blew it out after your previous dive. But, of course, all fast-water dredgers get many chances to experience this. It is a normal part of the routine!

One important safety point: When using ropes underwater, it is a bad idea to use any more than is absolutely necessary. A lose rope is poison to divers underwater, especially in swift water! Always cut off any excess rope or pile rocks on top to hold it down. If there is a length of loose rope flopping around in the current, something (like your air line) always seems to get tangled in it. Loose rope under water is dangerous!

Your air line can be another source of problems when dredging in fast water. Always be sure to get all the loops out of your air line before starting your dive. Otherwise, the current can pull these loops into kinks, which can immediately cut off your air supply. Not fun!

When you turn around in your dredge hole to roll boulders, toss cobbles, or do any of the many other things associated with production dredging or sampling, get into the habit of exactly reversing your turn when you face forward again (turning back counterclockwise is “cancelled out” by turning forward clockwise). This practice will help prevent you from putting lots of loops in your air line during the course of the dive. Each loop is a potential kink that can cut off your air supply in fast water. Each loop also increases the amount of drag being brought to bear on your air line in fast water.

If you should get a kink in your air line that cuts off your air supply, you can usually get some immediate relief by pulling your air line in toward your body and letting it go. When you let it go, the pressure is temporarily removed from the kink, and you can usually get a single breath of air. I always try this once, quickly, when my own air is suddenly cut off. If that does not give me immediate relief, I crawl right over to the surface so I can properly correct the problem.

If you are experiencing any difficulty with a kinking air line, your best course of action is to immediately remove every single loop in the line. Getting rid of the loops will require you to rotate yourself in circles, going in the appropriate direction, until the air line is straight again.

Several years ago, I was dredging in fast water with a guy who had to repeatedly dive out of our dredge hole because of a kinking air line. After about the fifth time, I suggested that he take the time to straighten out his air line to fix this problem. This remedy only worked for a short time, because he had developed the habit of turning around and around in the dredge hole as he was moving rocks, which just created more and more loops in his line. Fifteen minutes later, he was diving right back out of the dredge hole again.

These days, you can buy a heavier-type of “safety” airline that will prevent kinking in all but the swiftest of fast water. I recommend this heavier air line to anyone who plans to dredge in swift current.

By the way, your air line is also your direct connection to the dredge and to safety. When you connect your air line to the dredge, even in slow water, it should be wrapped around the dredge frame several times before being attached to the air fitting on the dredge. Most air fittings are made of brass. If you should need to use your air line to pull yourself to the dredge in an emergency, it is better that you not have to depend solely upon the strength of a brass fitting!

Nearly all experienced dredgers are aware of the fact that their air lines are an extension of themselves while under water. Especially in fast water, it is very important that you not allow your air line to tangle around parts of the dredge, underwater obstacles, and/or the air lines of other divers in the dredge hole. If you cross over the top of another diver’s air line, keep that in mind, so you will be sure to cross back over it again when you return. Each time you go to the surface, to remove a plug-up or for whatever reason, take a moment to untangle your line from anything it may have wrapped around. As a standard practice, all dredgers should always untangle your air lines each time you return to the surface for any reason. I personally never end a dive without first freeing my airline completely, so it will be ready for the next dive.

One of the persistent problems of dredging in fast water is the heavy drag on your air line. This can normally be solved by pulling some slack-line into the dredge hole and anchoring it against the current with a single cobble placed on top. This will allow some slack air line between you and the cobble. You want to be sure that your cobble-anchor is not so large that you cannot quickly free your air line in an emergency. Also, when you leave the dredge hole, don’t forget to first disconnect your air line from your anchor.

Full face masks are generally not well-suited for diving in swift water. Since they are larger, with substantially more surface area, they are more likely to get accidentally dislodged from your face. This can happen when the mask is bumped on another diver, or an obstacle, or when turbulent water catches it, especially from the side. To further complicate matters, when a full face mask fills with water, the regulator usually does as well. Having to clear the water out of your mask and regulator at the same time can be more difficult and contribute to a panic situation. I personally find that I am more prone to feeling panicky when something goes wrong inside of a full face mask. If your reactions are similar to mine, you may want to avoid using a full face mask in fast water.

DO’S AND DON’TS!

In any kind of a dredging operation, fast or slow water, it is wise to become familiar with your surroundings as your first priority. Before you begin work, make sure you know the easiest and most direct route to crawl over to the surface in the case of an emergency. Don’t wait until an emergency happens before you think about this. By then, it is too late!

Here is some really good advice: Do not tie yourself into a dredge hole in fast water to keep from being swept down river. It is bad enough having a heavy load of lead attached to your body! If you have to tie something, tie the suction nozzle from a point further up river (with no loose rope flapping in your face). Then hold onto the nozzle to keep yourself steady and in place, while you get the hole started. Get rid of the rope as soon as you have a hole started!

Generally, the most effective way to maintain your position in fast water is to streamline your body properly, with your head and chest close to the river-bottom and your rear-end slightly elevated. This posture allows the water-flow to push you down, toward the bottom, so you can get a better footing. Begin creating your dredge hole as soon as you can. The hole will help anchor you in place. The larger you dredge the hole, the easier it gets.

Some dredgers try to solve their stability problem by putting a lot more lead on their weight belts. Sometimes in turbulent water, more lead can be a help. But, be extra careful when walking out of the water on the slippery bottom, so you don’t overload your ankles and knees and injure yourself.

Most importantly, it is very unwise to solve your fast-water buoyancy/stability problem by adding a bunch of additional weight belts. Take it from me; it is hard enough to get one belt off in a hurry, without compounding the emergency with three of them! Sometimes, you cannot manage the needed extra weight without 2 weight belts, but you must understand that a second belt substantially reduces safety margin in an emergency. Additional belts tend to shift around so that the quick releases are in different places, often behind you where it is more difficult to release them during an emergency. Difficulty in finding them in an emergency can contribute to a panic situation and put your life at risk.

Whatever else you do, early in your dredging career, it is wise to discipline yourself to never try and swim for the surface in an emergency while wearing your heavy weight belt. It just doesn’t work! In a panic situation, your body will want to go immediately for the surface instead of removing the weight belt. I have personally saved two people from drowning who were trying to ”swim for it” with their weight belts on. By the time they realized swimming was not going to work, they were in too much trouble (panic) to get their own belts off!

This does not mean you can’t get a good footing on the bottom and jump up to the surface for one quick breath of air. You can do that in an emergency, as long as the water is not too deep or fast. But, if you cannot crawl over to the surface quickly, your first priority should always be to get the lead weights off as soon as possible.

Keep in mind that you usually cannot see the quick-release buckle on your weight belt while underwater. This is because your face mask blocks your vision at that angle. So, it is important to practice locating the quick-release buckle by feeling for it. It is also very important to keep your belt from shifting around, so that the buckle always remains directly on the front of your body. One of the problems we already noted when wearing more than one belt, is that the top one tends to shift around. There is not much you can do about that. So with two belts, you should be prepared to find the top buckle behind your body!

You may also find that it is better to first remove your work glove before trying to release your buckle in an emergency. When I get in trouble, the first thing I do is get rid of the glove on my right hand!

These are all things you must be able to do quickly and instinctively before venturing into fast water. A wise skydiver would never jump out of an airplane without first receiving enough practice and instruction in how to find his rip cord. Similarly, a dredger’s life should be just as well protected by having a confident ability to release your weight belt quickly in an emergency.

Some of the weight belts on the market also include a suspender harness. The only ones I recommend are the ones that have a quick-release, D-ring on one of the suspenders that allows the shoulder harness to come loose on one side when you release a single waist belt buckle. Otherwise, in an emergency, you may find it too difficult to get out of the suspenders, even if the waist belt is released.

All this advice is coming from a guy that has devoted a large part of my life living on the edge. You can sit there in the comfort of your computer reading this stuff and feel quite certain that you can manage any or all of these things if they should come to pass when you are out dredging. But when the severe emergency happens, you are not the same person. You are a maniac!

You should always keep an eye on your diving buddy while dredging in fast water. When we dive with multiple dredgers on an operation, it is standard policy for us all to keep track of each other. If one person needs to leave the dredge-hole or go to the surface for some reason, he always lets someone know he is leaving. Otherwise, when a diver suddenly disappears, we immediately go looking for him. A person in serious trouble underwater only has about 30 seconds to get it together. This is not much time. What good is diving with someone else for the sake of safely, if you are not paying attention to what is happening with him/her, especially in fast water where there is so very little margin for error? A tender, or anyone else resting at the water’s surface, should be paying close attention without distraction when there are dredgers down working in fast water.

If all of this has frightened you, that’s good! That means I have accomplished my goal of alerting you to the dangers inherent in fast-water dredging. Being alert to, and fearful of, those dangers is the starting-point for making your own preparations and contingency plans for dealing with them – before you start working in fast water.

What is fast water? It depends upon the individual. An experienced dredger might be much safer in a typhoon of fast, turbulent water, than an inexperienced person would be in slow, shallow water near the bank. The key for each person is to begin learning in a safe and comfortable environment, gain valuable experience over time, and never attempt to do anything that you cannot easily manage, with safety.

 

 

By Dave McCracken

Specialized metal detectors will detect gold well-enough that they will sound-off on nuggets, deposits of smaller pieces of gold or even very small individual flakes of gold.

Dave Mack

 

 

Chrissy with her gold and metal detectorThere are many different kinds and models of electronic metal/mineral detectors to be found on today’s market. This is a guideline to give you the basic knowledge to help you choose the proper detector for your prospecting needs, and to help you use your metal detector as an effective prospecting tool.

There is a lot of electronic prospecting and gold nugget hunting activity going on at the present time. Consequently, there are different tools being used, along with several different popular approaches in how to properly-tune a detector and how to achieve the best results while searching.

It is important to point out that no two gold-bearing areas are exactly alike. An approach which might work better in one area, might not work very well in a different area. So, the purpose of this article is not to tell you what I think “the best” approach is. It is to give you information about each of the different approaches, so that you can gain a larger bag of tools to use when confronted with different situations out in the field.

I should begin by mentioning that the type of electronic detector used to find gold and other precious metals is not a “Geiger counter.” A Geiger counter is an entirely different electronic tool which is used to detect radioactive elements.

The type of electronic device used to prospect for gold is called a metal/mineral detector (“metal detector,” for short). Metal detectors are quite simple to use (once you understand them), and can be helpful in assisting you to locate gold or silver deposits or specimens once you have gained some personal experience in using one properly. While they are rather simple to use, it does take some practice with a metal detector before you can use one proficiently in gold prospecting activities.

There are many different models of metal detectors being offered on today’s market, most which are more useful to the treasure hunter than the gold prospector (two entirely different fields of detecting activity and procedure). Those detectors of most use to gold and silver prospectors generally fall under two separate categories: Beat Frequency Oscillator (“BFO”), and Very Low Frequency (“VLF”).

BEAT FREQUENCY OSCILLATOR

First we will take up the BFO, which is the simpler of the two—but is less-often found these days, due to the substantial electronic advancements of VLF detectors.

The BFO detector usually has two main settings, which are “metal” and “mineral.” As far as electronic detectors are concerned, the difference between the two is that “metals” are targets which are conductive of electricity–such as copper, gold, silver or iron. And, “minerals” are targets, or target areas, consisting of magnetic non-conductive materials such as magnetic black sands (Fe304). These are also known to prospectors as “black sand concentrates.” Electronic prospectors generally refer to them as “heavy ground mineralization.”

An iron object which has been in the earth for an extended period of time, and having thoroughly oxidized, will usually read-out on a metal detector as a mineral instead of a metal object–which it no longer is.

So the two basic settings on a BFO detector are “metal,” electrically conductive targets (gold and silver), and “mineral,” non-conductive magnetic particles (magnetic black sands).

The various models of detectors have different ways of sounding-out on reading targets. Some detectors have a light which turns on and off. Some have a meter with a needle on a dial–which will also give you an idea of the intensity of the signal given-off by various targets. Other detectors have a tone which changes in volume or pitch when passed over a reading target. Some newer-model detectors have an LED display which spells-out the different types of targets being encountered. Some detectors have a combination of these features.

Generally, the best type of metal detector for prospecting purposes is the type which includes an audio tone in which the audio pitch changes when the search coil is passed over a reading target, and which also allows a set of headphones to be connected. The advantage to using headphones while prospecting is that you can shut out the background noises from the surrounding environment and concentrate more intently on even the smallest audio changes which can and do occur while searching.

On most tone-changing BFO detectors, the tone will not only raise in pitch when the search coil is passed over a target for which it is set to sound, but it will also lower in pitch when the search coil is passed over a target of the opposite setting. For example, if a BFO detector is on the metal setting and is passed over a large gold nugget, the detector’s audio tone should rise in pitch. If the detector on the same metal setting is passed over top of a high concentration of magnetic black sand, the audio tone should lower in pitch. The same thing holds true in the opposite for the BFO detector which is adjusted to the mineral setting.

One other interesting thing to know about BFO detectors is they generally sound-out on the most dominant element, either “metal” or “mineral,” whichever is most present in the ground which the detector is being passed over. For example, if you are passing the search coil over ground which contains gold (this would read as a metal), yet there is a large amount of magnetic black sand in the same ground, it is likely that the BFO detector will read-out on the black sand as a mineral while ignoring the gold. Equal reading-amounts of both metal and mineral elements in a section of ground, in any quantity, will prevent the BFO detector from sounding-out on either element.

Because BFO detectors read-out so well on highly-mineralized ground, the presence of highly-mineralized ground tends to block-out reading traces of gold which lie in or under. This is known as “interference” in the electronic detecting field. Magnetite (magnetic black sands) has such a strong affect on metal detectors, that a concentration of only one percent magnetite in the ground may create a signal-imbalance which is hundreds of times stronger than the signal which might be given off by a small gold nugget.

So, a mineral reading on a BFO detector does not mean there is no gold present, only that there is heavily mineralized ground—which may be blocking-out gold readings.

One of the problems in electronic prospecting is that gold targets are often associated with highly-mineralized ground. Therefore, as a tool, the BFO has its advantages and limitations. In some prospecting situations, it can be very helpful to have a device which is good at pinpointing areas of concentrated heavy mineralization. The BFO does this exceptionally well.

This is further-discussed in my other article on this subject: Prospecting for Gold with a Metal Detector.

Some places where nuggets and larger flakes of gold become trapped do not allow heavy concentrations of black sand. One example of this would be a location (rapids) where the water runs fast over top of exposed bedrock during major flood storms. Such areas can be well out of the active waterway and directly accessible to metal detecting. BFO detectors can be very effective at helping to locate gold targets in places where heavy mineralization is absent.

GOLD TARGETS

Unfortunately, as a metal, gold is generally not picked-up very well by metal detectors. This is a comparative statement. Gold does not sound-off on a metal detector nearly as well as an iron object of the same size and shape. However, specialized metal detectors will detect gold well-enough that they will sound-off on nuggets, deposits of smaller pieces of gold or even very small individual flakes of gold.

No metal detectors are able to detect particles of gold dust at the time of this writing. This is probably a good thing, however; because there is so much fine gold spread throughout gold country that it would probably create additional interference problems on a sensitive gold detector.

Therefore, in electronic prospecting for gold, we are looking for flakes, nuggets and accumulations of gold. These are targets which will add up more quickly to something of good value.

It is important to understand that different makes and models of metal detectors are not equal in their ability to detect gold objects. Some detectors will just barely sound-out on gold objects. Others will not sound-out at all.

I highly recommend that any person who is buying a metal detector for gold prospecting purposes should bring along some samples of natural gold to test the various detectors before deciding which one to buy.

Small samples of natural gold and small nuggets are readily available by doing a search on the Internet or contacting a prospecting shop. This is to be sure that the metal detector you do buy will sing-out well when it is passed over natural gold objects, even very small gold targets. If a specific detector will not sound-out on gold held in the air, it will most-likely never detect gold targets located in the ground.

When testing-out the various detectors, it is better to use natural gold samples—like nuggets, flakes or a sample bottle filled with smaller-sized gold,. Some detectors will, and some will not, sound-off on small bottles that are filled with fine gold. Using natural gold targets is better than using a gold ring or some other type of jewelry. Jewelry is nearly always made of gold which has been alloyed with other metals (like copper)—which may read-out on a metal detector better than natural gold objects. Therefore, gold jewelry might give you a wrong idea about how well a metal detector will sound-out on natural gold targets.

The best detectors for finding gold are not necessarily the most expensive. Varying costs in detectors are sometimes in proportion to the amount of additional electronic circuitry that is built into the detector for extra features. These sometimes have little or nothing to do with the detector’s capability of locating gold targets.

Gold targets give a solid, mellow sound on a metal detector, similar to lead or brass. Pieces of steel wire and bigger nails usually give a stronger beep—or often a double beep.

The capability of a metal detector to sound-off on a natural gold target will partly depend upon what other metals the gold is alloyed with. Silver and copper make natural gold targets sound-out stronger. Nickel, mercury and platinum alloys make natural gold targets more difficult to find.

Metal detectors read-out on gold better as the pieces become larger. As an example, an average gold detector might sound-out very well when its search coil is passed over an eighth-ounce nugget from several inches away, yet not sound-out at all when passed over three times as much fine gold accumulated in a glass jar at the same depth or distance from the search coil.

Actually, it is not just the size of the target which counts. The object’s shape also makes a difference, and also the direction which a target is facing. A larger, more solid surface-area of gold will sound-out stronger. For example, a flake-shaped nugget is likely to sound-out better on a metal detector than a round nugget of the same weight, as long as the flat-surface area of the flake is facing in the direction of the metal detector’s search coil. Also, coarse and irregular-shaped nuggets, as commonly found in dry placer areas, residual and eluvial deposits, do not generally sound-out as well as nuggets which have been worked-over and pounded by flood storms in a streambed (because these are more dense and solid).

How tightly a gold deposit is concentrated also makes a difference in how well it will cause a metal detector to sound-out. Whereas a quarter-ounce of flake-gold inside of a jar might sound-out well on a particular detector, perhaps two ounces of the same flake-gold spread-out over a slightly larger area might not read-out at all with the same detector when the targets are at the same depth beneath the surface. This is one factor which is important for the gold prospector to realize: Any metal detector wills read-out on tighter concentrations of gold better than larger amounts of gold which are more widely dispersed. Metal detectors will also read-out on nuggets (larger solid pieces of gold) best of all.

DEPTH CAPABILITIES

How deep into the ground that a specific metal detector will sound-out on an object depends upon various conditions. Surprising to many, how much a detector costs may not have much to do with its depth-sounding capability. In fact, some of the less-expensive models are able to probe deeper, and pick up on gold better, than some of the more expensive detectors. The Federal Communication Commission has put a maximum limit on the signal-strength which can be used in metal detectors. So the idea that a more expensive model puts out a stronger signal to probe deeper is simply not correct.

The type of object has much to do with how deep into the ground that it can be located with a metal detector. Different kinds of objects have varying amounts of magnetic and electrically-conductive properties. Therefore, they affect metal detectors differently. Also, some detectors will sound-out on some kinds of objects better than others. As mentioned earlier, gold is not one of the better-reading metals, so cannot be picked-up with a metal detector as deeply as an iron object of similar size and shape.

Another factor which determines how deep an object will be picked-up by any detector is the size of the object itself. Whereas a 2-pennyweight nugget (1/10th ounce) might be picked up five inches deep into the ground with a certain metal detector, a 5-pennyweight nugget (1/4 ounce) might be picked-up eight inches deep into the same ground with the very same detector.

How much an object has deteriorated and has been absorbed into the soil is another factor in how deep the object will be picked-up. Iron objects tend to oxidize and become slowly absorbed into the surrounding material. This causes the target to appear larger and read-out more strongly, so it will be picked-up at greater depth with a metal detector. Once such a target has thoroughly deteriorated as an object, it will stop reading as a metal and start reading as highly-mineralized ground. Gold does not oxidize or deteriorate, so this factor does not apply to natural gold targets.

The size of a search coil on a metal detector is also a factor in how deeply the detector will locate objects. Larger coils generally are able to detect objects at greater depth than smaller coils. But they generally do not have as much sensitivity in detecting smaller gold targets. Smaller search coils have greater sensitivity to small objects, yet do not have the depth-probing capability that larger coils do. Medium-sized coils, from five to eight inches in diameter, often combine the features of having both a reasonable amount of sensitivity for the smaller objects, and acceptable depth-scanning ability.

One thing to keep in mind is that a larger coil will also increase the size of the area being covered by each sweep.

Many nugget hunters prefer to have a smaller search coil handy, because it produces the greatest small-object sensitivity (gold flakes), and because the smaller coils can get into tighter spots—like in and around tree roots and inside of exposed crevices in the bedrock, where nuggets are most likely to be found with a metal detector.

Almost all detectors today are made so that various-sized coils can be attached, depending upon what they are to be used for. When testing a detector, do not make the mistake of assuming that if the device sounds out well on a gold sample when using a coil of one size, it will also sound-out well when using a coil of a different size. Your best bet is to test the detector with the various-sized coils to see which work best for your particular needs.

One of the most important factors determining how deep a metal detector will sound-out on a gold object is how much mineralization (interference) is present in the ground that is being prospected. More minerals equal less depth. This is especially true of BFO detectors. Because black sands usually exist, and sometimes actually concentrate, within the very same streambeds or soils where gold deposits are located, metal detectors are not always used to directly detect gold in streambeds or material of substantial depth. They are sometimes used to scan places where there is a very shallow amount of gravel or material (if any) present over top of the gold (exposed bedrock).

One excellent use of the BFO detector as a prospecting tool is to locate concentrations of black sands in a streambed. Black sands often accumulate in the very same locations that gold does (pay-streaks). From your fundamental knowledge of placer geology, after potential pay-streak locations have been pinpointed, those specific areas can sometimes be scanned with a BFO detector to locate the increases in other heavy elements. Specific sites which sound-out heavily on the “mineral” setting can then be sampled by conventional gold mining techniques.

VERY LOW FREQUENCY DETECTORS (VLF)

The VLF detector is a more recent development in the field of electronic prospecting. Very Low Frequency detectors may come under other names or descriptive abbreviations such as VLF, GEB, MF, GCD and others. These are designed with circuitry which is able to cancel-out the effects which highly-mineralized ground has on a BFO detector. VLF detectors have the ability to look through or past highly-mineralized ground and detect metal objects (gold) that may not read at all on a BFO metal detector.

The VLF, being able to cancel-out interference caused by mineralized ground, is more suited for locating gold deposits and gold specimens directly. However, it still remains true that gold targets will have to be large enough, or located close enough to the surface, or deposits will have to be tightly concentrated enough, to sound-out on a VLF, just as with a BFO detector.

Just because a particular detector is of VLF design, does not mean it will sound-out well on gold. In fact, there are some VLF detectors which have difficulty in sounding-out on gold samples at all. So this type of detector must be just as thoroughly tested using natural gold targets before buying for prospecting purposes.

The VLF detector, being a mineralization-cancelling device, sometimes does not have the ability to detect the heavy black sand concentrations the way a BFO detector is able to. Consequently, a VLF is more often better-suited for scanning directly for gold, whereas a BFO is generally better-suited in helping the prospector locate gold deposits in an indirect sort of way, by finding the highly-mineralized ground within a gold-bearing area.

MULTI-PURPOSE DETECTORS & SPECIALIZED GOLD DETECTORS

VLF detectors are sometimes also constructed with discrimination circuits that are designed to cancel or identify specific types of targets—like bottle tops, aluminum foil and pop-tops. For the most part, this type of electronic circuitry is better-suited for treasure and coin hunters. When used in prospecting for gold targets, discrimination circuitry sometimes has a tendency to also reduce the detector’s depth-probing capability, especially in highly-mineralized soil or streambed material. Since gold targets are already difficult to locate, it can sometimes be better to not utilize additional circuitry which could hamper sensitivity towards gold.

However, some conditions do exist in which discrimination circuitry may assist a gold prospector. If using such a detector, always test it against a sample-nugget planted in or on the ground that you are probing, to determine whether or not you can trust the discrimination circuitry.

There is a lot to be said about having a small natural gold target along with you at all times when you are prospecting for gold with a metal detector. This way, each time you decide to try something new to try and get the most out of your detector under changing circumstances, you can confirm the results using a target which is similar to what you are hunting for. It is common for electronic prospectors to glue a test-nugget for this purpose to a poker chip, which can be tossed to the ground and easily spotted again.

Some of the newer, specialized VLF gold detectors are utilizing specific discrimination circuitry called “Iron Identifiers.” This does not necessarily reduce the total depth capability in the detection of gold targets. In other words, the circuitry will identify iron objects which are nearly certain to be iron. The downside to the use of such circuitry is that if an iron target is too deep or too small, it might still be identified as iron. Also, if the ground is highly-mineralized, the accuracy of iron-identifying circuitry is likely to be reduced.

The best gold detectors which use a meter or other display to identify different types of objects, do not route the discrimination function through the same circuitry that produces sound variations through the headphones. In this way, you can obtain optimum depth probing and object sensitivity to your ears, along with some added visual ability to pre-identify what is sounding-out on the detector. This is all about reducing the amount of trash targets that you must dig up while looking for gold.

Some experienced electronic prospectors utilize discrimination circuitry (turning it on and off accordingly) only after a target has been located. This way, depth and sensitivity is not forfeited during preliminary searching.

Other experienced prospectors insist that no discrimination circuitry is needed. Once you are familiar with the area you are searching, and know the specific audio tone changes of gold and/or trash targets, you will form your own judgment of which targets (sounds) to dig and which targets to leave alone. Different prospectors have different methods. Also, different locations often require different methods. Some experienced electronic prospectors simply dig every target (sound).

Some VLF detectors are made with circuits designed to analyze targets. This means they are able to tell you if the target is a nail, bottle top, a nickel, silver dime or a piece of gold. Such circuitry has only limited accuracy in electronic prospecting; because highly-mineralized ground tends to interfere with the signal and can give a false reading in the analyzer. Still, the added capability can be useful.

None of these circuits are a problem with multipurpose detectors, providing the special circuits can be shut off or bypassed—and/or providing the additional circuitry does not hamper the detector’s efficiency in locating gold and silver targets.

Some VLF detectors are designed with manual ground-balancing controls, and others are designed with automatic ground-balancing circuitry. Some prospectors prefer the manual controls. Others prefer automatic ground-balancing. There is nothing wrong with automatic ground-balancing circuitry in gold prospecting, as long as it is fast enough to keep up with the rapidly changing mineralized conditions of the different areas you intend to prospect—and as long as the additional circuitry does not hamper the detector’s ability to locate gold and silver targets.

Some VLF detectors have been specifically designed as gold prospecting tools. Since most specialized gold detectors operate at a higher transmitting frequency, have extensive ground-balancing capabilities, and have special circuitry to avoid sensitivity overload in highly-mineralized ground, they definitely do have some advantages in their ability to locate small gold targets over most multipurpose detectors—or gold targets which are deeper in the ground.

The high-performance of some of today’s specialized gold detectors even make pinhead-sized gold targets recoverable.

Which detector you choose to buy will depend upon what you plan to use the detector for. If you plan to only use it for prospecting purposes, a special gold machine is probably best for you. If you intend to search for coins, caches, artifacts and lost articles, as well as prospecting for gold and silver, perhaps a multipurpose detector is best—or two separate detectors. Only you can decide.

I would suggest you buy your detector from a dealer located in the general area where you plan to prospect for gold. The local dealer will know which detectors are performing best in that area. Local dealers will also introduce you to other prospectors, and perhaps a local prospecting and/or treasure hunting club or association.

Communication with local prospectors can be a very big help in determining which detectors are best for specific areas. You can also get tips from them on productive places to prospect with your detector.

No detector made is the best for all locations. Some machines work better than others in wet or dry conditions. Some work better in hot or cold climates. Some detectors are affected by alkali “salts” in the soil or gravel more than others. When any of these examples is the case, a smaller coil might manage adverse conditions better than a larger coil. Each area is different.

Another reason to purchase your detector from a local dealer is the help and support that you will receive. Success in the field comes from understanding the workings of your detector, and perhaps receiving inside information on good places to hunt. The money saved by buying from a discount mail-order house may not be worth the loss of support you would otherwise receive from a local dealer—especially when you are just beginning.

When buying a detector which you intend to use for prospecting purposes, keep in mind that probably the most important feature is the detector’s capability of cancelling the heavy ground mineralization found in most gold-bearing areas.

Practice makes perfect. You must start with good equipment. The rest will be up to you.

ELECTRONIC PROSPECTING DRILLS

The following is a set of drills put together to give the new (or old) owner of a metal detector some practice with his tool and to allow him (or her) to get a good grasp of what the detector’s gold-finding capabilities are:

DRILL No.1: Take a file or electric grinder to a piece of iron or steel (like a nail), and allow the fine pieces of metal to fall into a container. Pour some filings onto a piece of paper and pour some glue over the filings to hold them intact. Pour more filings on top of the glue and then pour on more glue. Continue this until the conglomerate is giving off a strong mineral reading on your detector. Make three different sheets of mineralization; one giving off a very mild mineral reading, one causing a medium signal, and one which gives off a strong signal.

If you are already an experienced gold prospector, and have some black sand concentrates lying around somewhere, use a magnet to collect some magnetic black sand and use these instead of iron filings. Sometimes, you can get prospecting supply outlets to send you a small package of black sand concentrates. You can also find bags of mineral concentrates (which usually include some gold) which various sellers on the Internet market as panning sands. These are better than using a machine to create iron filings, because they are the actual material that you will encounter in the field.

These different mineralized conglomerates will give you a good idea of how your detector will react to different degrees of mineralized ground.

DRILL No.2: Acquire at least a half-ounce of placer gold, preferably more, with a variety of fine, flake, and nuggets so a wide range of testing can be done.

Carefully place the gold in a pile on a clean sheet of paper in a location where there is no other metallic object reading on your detector. Scan the gold with your detector from varying distances to get an idea of your distance-capabilities when scanning a concentrated gold deposit.

Now spread the gold out over a slightly-wider space on the paper and scan again to check distance. Continue to spread the gold out wider and wider until it no longer reads on your detector—or until you are picking up on individual flakes of gold. This drill will give you a good idea of what sized pieces and accumulations of gold will sound-out at what distances. Try different coil sizes to see what their capabilities are.

Pay particular attention to the specific sound-readings that you get when scanning over gold targets. These drills should be done with headphones. With some practice, you will start to be able to tell the difference between gold and other metallic sounds by the difference in the strength, crispness and tone of the signal. Stronger-reading metals will give a sharper and louder change in tone, whereas gold tends to cause a softer and more indistinct signal–especially when located in smaller amounts or at a distance. Do the drill and see for yourself.

DRILL No.3: Using the flake-gold and nuggets in different accumulations, as done in drill No. 2, place the different sheets of mineralization over the top of the gold and note the responses on your metal detector. If you have a VLF, practice cancelling-out the mineralized sheets and test to see what size-accumulations of gold can be picked-up while doing so. Try more and more mineralization, combining the sheets together if necessary, to see how much mineralization your VLF detector will look through and still have sensitivity to gold targets.

Notice how even a larger piece of gold puts out only an inkling of a reading when covered by heavy mineralization and/or scanned from a distance. Recognizing these very light signals is usually the difference between success and failure in electronic prospecting!

If you are doing these drills with a BFO detector, try combining different amounts of mineralization with the various-sized accumulations of gold. Determine for yourself on your own detector how much mineralization it takes to block-out the different accumulations of natural gold.

I am certainly aware that sometimes it is difficult to come by a collection of gold flakes and nuggets if you don’t already have a collection of your own. However, the time spent in locating some natural targets to practice with, or in talking a friend into lending you his collection–or in talking him into doing these drills with you—will be worth many times as much time spent out in the field with your detector.

These drills will not teach you how to prospect for gold deposits. Only practice and experience out in the field will do that. But these drills will go a long way to familiarize you with your detector and give you certainty on the use of it. They will help you with the basics that you will need to learn to prospect for gold with a metal detector.

HELPFUL TIPS ON TUNING

Each model of detector has its own set of operating and tuning instructions which you should follow. And, I highly suggest you familiarize yourself with every aspect of the manufacturer’s instructions. In addition, here are a few pointers which have proven successful in the prospecting field:

Some manufacturers recommend that their volume-changing detectors be tuned to just below the hearing range. The purpose of this is so that the slightest reading will make a sound— which can be easily distinguished from the silence. But for prospecting purposes, it usually works better if you tune your detector so the audio signal is always within hearing-range. This will use up the batteries just a bit faster, but it is much better to be able to hear the signal at all times.

The audio threshold (“threshold”) of a tone-difference sounding detector should also be set just in the hearing range. When looking for natural gold targets, just the slightest change can mean the difference of finding or missing a gold target. Changes in volume and/or audio tone also are an indication of changes in ground mineralization and let you know when adjustments are needed to ground-balance again and again.

Sometimes the detector’s audio signal will drift off to a lower volume range due to temperature changes or loss of battery life. If the audio signal is tuned into the non-hearing zone and drifts into an even lower range, you might be scanning for several minutes without having the detector tuned properly. That would just be a waste of time.

Sometimes a warming coil will cause the threshold sound to drift upwards. A cooling coil might cause the threshold to drift downward. Hunting in and out of water environments, while scanning the banks of a stream, might cause threshold changes. You should make adjustments as necessary.

The main cause for a detector’s tuning to drift is loss of battery life. When this occurs, it is time to replace the batteries with a new set so you can get the best performance out of your detector—which is needed when hunting directly for gold.

It is always a good idea to bring along an extra set of batteries into the field when prospecting. Because when they quit, you are finished until new batteries are installed. Extra batteries should be kept cool and dry. Zip-lock baggies work well for this.

Prospecting for gold targets directly with a VLF detector should almost always be done in the “all-metal” mode.

Setting Sensitivity: It is important to stress that you do not want to set the sensitivity too high on your VLF detector while prospecting in a heavily-mineralized area. A high sensitivity setting while testing a nugget in the air will show improved perception—and therefore can give you a false impression of the detector’s scanning ability for gold targets in the ground. It is better to do your settings while scanning over your test-nugget on the ground that you will be searching over.

Turning the sensitivity up too high in mineralized ground is similar to using high-beam headlights in the fog. You get lots of flashback and irregular sounds and false targets. If your sensitivity is set too high, your detector will operate in an erratic manner. There will be many false signals which do not repeat themselves (“flashback”).

Consequently, less sensitivity can give you more depth-penetration in mineralized ground. There is actually a middle ground, depending upon ground mineralization, which will give you optimum sensitivity without too many “ground noises” which are confusing and prevent you from selecting the real targets. Try and run with the sensitivity as high as possible—until the steady tone of the threshold begins to give off an uneven, wobbly sound while you are scanning.

I usually do not recommend using the factory preset marks on your detector controls. Such settings are for average conditions. Prospecting for gold targets requires continuous adjustment to ground-balancing, and the threshold and sensitivity need to be set as accurately as possible to ever-changing conditions. You need to get the most possible out of your detector to avoid missing gold targets.

“Peak Performance” on a metal detector for nugget hunting purposes in most cases is: maximum volume on detector, threshold set in minimum audio hearing range, maximum sensitivity without receiving too much flashback, and ground-balance to the average ground being scanned. When you accomplish peak performance on your detector, the rest is up to you! By this, I mean you will have to interpret which signals should be dug up.

Ground-balancing: Setting the proper ground-balance on your detector, and keeping it properly adjusted while you search, is perhaps the most important factor in successful nugget hunting. I cannot overstate this point; because without proper ground-balance, you simply cannot find natural gold targets—unless you just get lucky. All of the skills we will talk about in this article, skills and methods which will make you good at finding gold targets, all depend upon your detector being properly ground-balanced.

Always set your ground-balance to the average soil or material which you are searching. You will find the majority of gold nuggets in average ground. If you ground-balance to specialized heavier-mineralized zones which are not the average matrix, you may forfeit some depth-probing capability or sensitivity to smaller or deeper gold targets.

Detectors which come with permanently-set, predetermined ground-balance are usually not especially good for electronic prospecting.

You should hear a low hum when your detector is turned on properly (threshold sound). As the detector is raised or lowered from the ground, the threshold hum should get louder or softer. This tells you what needs to be done to get a proper ground-balance. Handling the ground-balance knob or button on your detector is similar to handling the volume control of a radio. If the threshold hum is disappearing as you lower the coil to the ground, turn the knob up. If the hum gets louder as you lower the coil, turn the knob down. The basic idea is to adjust the ground-balance knob (or press the button) until rising and lowering the coil to the ground creates little or no change in the threshold hum.

Ground-balancing has to be redone on a regular basis while prospecting. The reason for this is because placer deposits do not contain uniform amounts of magnetic mineralization. Water-flows create low pressure zones and high pressure zones from one place to the next. These different zones accumulate different amounts of mineralization during flood storms. Often, you can see changes in mineralization just by noting changes in the color or surface of the ground you are scanning. Also, changing from gravel-like material to bedrock surfaces almost always changes the amount of ground mineralization. Get into the habit of re-ground-balancing about every 15 or 20 feet, or about every five minutes, or whenever the ground conditions change.

Your detector will tell you what is going on. If the threshold hum is getting louder, it usually means there is less mineralization in the ground you are now searching. If the hum goes softer, the mineralization is increasing. With a little bit of experience, you will gain your own perception of when it is time to re-ground-balance.

It is almost never a good idea to balance a detector over top of a piece of metal in the ground. Move around until you find a non-reading area to ground-balance.

When ground-balancing, move your coil all the way down to touch the ground if possible. I say “if possible,” because you occasionally run across areas with so much mineralization that you are not able to put the coil within a few inches of the ground! “Alkali salts” in damp soil can sometimes also create so much interference that the coil of your detector needs to be raised several inches above the ground to search for targets. Naturally, depth penetration is lost by doing this. But sometimes you have no other choice. Sometimes you can also get around this problem by making adjustments to your detector’s sensitivity. This will allow you to search with your coil closer to the ground; but the reduced sensitivity will likely eliminate some perception of smaller or deeper gold targets.

Sometimes, you can obtain better results by ground-balancing your detector a little on the positive side. A slight positive ground-balance increases the detector’s sensitivity to smaller gold targets when hunting in an area of lighter mineralization. This means that the threshold makes a slightly louder hum as the coil is lowered to the ground. When operating this way, be sure to keep the threshold in the audio hearing range. You don’t accomplish this by adjusting the threshold; reset the ground-balance as necessary to remain in the audio hearing range when lowering the coil to the ground. Just a slight positive ground-balance boost is all that is needed. Some experienced prospectors like to operate in a positive range all the time.

However, you may find instances when working around highly irregular ground, vegetation and/or rocks when a slight positive ground-balance creates a problem. Lifting the coil up and down and around with a positive ground-balance setting can create a similar situation as with too much sensitivity.

In highly-mineralized ground, when there are too many flashback signals which could be real targets, you can try ground-balancing your detector to a slightly negative setting with the coil on the ground. This may reduce your sensitivity to some of the smaller gold targets. But it is likely to settle-out your machine, and it might make it possible to locate targets which otherwise would not be accessible.

Always bring along your small sample natural gold target (about the size of a match head). This should be glued to a bright colored poker chip, or something similar, to keep it from being lost. Some prospectors go so far as to drill a hole and tie a string to the poker chip to avoid losing valuable time searching for lost poker chips! When in doubt about your tuning, toss down the sample gold target, cover it over with the ground in question, and see how your detector reacts. It might not be necessary to cover the test-nugget. Just placing it on top of the ground may be enough to test the tuning of your detector over that type of ground.

One thing which should be mentioned is that while you are searching around, your threshold hum is likely to change. The answer is usually not to reset the threshold; it is to adjust ground-balance and sensitivity as necessary to challenge the changes in ground mineralization. Your sample gold target will be the final test of whether or not your adjustments are working. If you don’t have a small natural gold nugget, you really should get one! Otherwise, a small piece of lead will create a similar target.

Other Tips on Tuning and Setting up a Metal Detector for Prospecting: When you are operating a metal detector, it is good practice to remove all rings, bracelets, watches and other jewelry from your hands and arms (ankles and toes). They can give a false read on the detector. This is especially true when you are testing a detector before buying, or when you are tuning your detector to sound-out properly on a special metal target while passing it over or under the search coil with your hand. Sometimes, belt buckles, canteens, knives and other digging tools or large metal objects carried on a belt can create false signals when using the more sensitive and specialized gold detectors. Even metallic eyelets on boots can cause problems when scanning too close to your feet. It doesn’t take much practice to figure out how to solve these problems.

Make sure to adjust the shaft-length on your detector to a comfortable position. Bending over too far will create uncomfortable back strain when hunting for extended periods.

Also, when the angle of the search coil on the shaft is changed to fit a new set of search conditions, the detector must always be re-tuned to correspond with the new relationship between the coil and the metal shaft.

Some prospectors prefer to mount the control box of their detector on their belt or hip. This lightens the arm-load during longer periods of prospecting activity.

It is also a good idea to wind the coil connection cable firmly to the shaft. This way, it is not flopping around, giving false signals or getting caught on objects and vegetation. Be careful not to pull the cable so tight as to break inner wires and create irregular operation of the detector.

OTHER IMPORTANT FACTORS TO CONSIDER WHEN BUYING

If you are looking over a metal detector you are interested in buying, test it to make sure that its tuning does not drift on its own. This test can be done by placing a good set of batteries into the device, turning it on, allowing it to warm up for a minute, tuning it in, and allowing it to sit and run for 5-to-10 minutes. If the audio tone drifts during this time, you ought to look around for a similar detector which has better electronic stability.

CAUTION: Wetness and dampness are not good for the control box of any type of electronic detector. Be careful to avoid getting yours wet when working around water. If you intend to use a detector out in the field on a damp or rainy day, you can cover the control box with a clear, loose-fitting plastic bag and secure it to the shaft of the detector. The bag should be loose enough so you can work the various control knobs without having to untie the bag and take it off to setup or re-tune the detector.

HEADPHONES

It is important in electronic prospecting to use quality headphones. This point cannot be over emphasized. Some detectors work just fine with the headphones which come from the factory.

There are different types of headphones. Some are heavy and cover the ears thoroughly. Some are light. What is best for you will depend largely upon the conditions where you are going to search. For example, the heavy type which thoroughly covers the ears might not be very practical in the hot, quiet desert environment. But they might work exceptionally well in a cooler environment—say along the bed of a creek where running water is making lots of background noise.

Areas which include the company of occasional rattlesnakes might require the use of lighter, less sound-proofed headphones!

The proper headphones for a specific hunting environment are another area where the local dealer or members of the local prospecting club can make valuable suggestions.

It is a common practice for prospectors to shorten the length of cable on detector headphones to about 3 1/2 feet. This helps prevent the cable from snagging on branches and other obstructions when working in brushy areas or climbing over uneven terrain.

Some detectors have volume controls and others do not. Volume on a detector while prospecting should normally be turned to maximum. Don’t confuse this with threshold hum, which should be set near minimum audio level. If maximum volume on the detector is uncomfortable to you, obtain a set of headphones which have volume control. Then, turn your detector’s volume all the way up and use the headphone controls to turn the volume down if you must.

Many electronic prospectors highly recommend “sensitivity enhancers”—like those made by DEPTHMASTER. These help enhance the soft target sounds from gold, while lessening the noisier signals caused by trash and iron targets.

OTHER HELPFUL EQUIPMENT

A plastic cup or tray is sometimes necessary to recover gold targets, even in dry terrain. A plastic gold pan is helpful to work down material where water is present. Sometimes a portable garden rake is helpful for moving smaller rocks and obstructions away from a productive hunting area. A small G.I. shovel is helpful in some hunting environments. A canteen filled with liquid; tweezers, needle-nose pliers for removing gold from bedrock traps; and a small pick for digging and scraping. Sometimes the ground can be very hard. This is especially true when finding gold on hard caliche layers in the desert. A wide belt with a carpenter’s loop (for holding hammers) comes in very handy for a small pick. This keeps it out of the way, but also makes it quickly accessible.

A lot of your gear can be left at your vehicle, or carried in a backpack which can be set down at the hunt site. It is usually better to not load yourself down too heavy while prospecting with a metal detector.

Many electronic prospectors are using empty 35mm film containers to contain recovered gold targets. These are unbreakable, and the large mouth makes it easy to get a piece of gold inside. Zip-lock baggies are also helpful.

A magnet can be a very big help while electronic prospecting. Sometimes you can recover a faint-reading iron target right out of the dirt with a pass of a magnet. Otherwise, you might find yourself losing valuable minutes picking through the material, looking for a small piece of gold. Animal feed stores commonly stock a special magnet used for cows (traps small iron particles, preventing them from entering and damaging intestines). These magnets are powerful, yet inexpensive. You can mount one on the end of your small digging-pick or tape it to the handle of a plastic or stainless steel garden trowel. This way, the magnet is handy when you need it. Some prospecting picks are available which already have a magnet attached; very convenient!

A serrated-edge on a garden trowel also is helpful when you find yourself digging around roots or brush. Some prospectors keep one edge of their trowel sharpened just for this reason.

When working bedrock areas, a small crevice tool can be a big help to open cracks and crevices which are sounding-out on your detector.

Some kind of pouch or pocket creates a location to dispose of small pieces of trash and iron which you dig up. You only want to dig it up once! It is much better to remove all small trash targets from the playing field. With the continuous improvement of electronic prospecting tools, you could find yourself going back over the same areas again at a later time!

Some prospectors are using fishing or photography vests—lots of pockets. These come lightweight or heavy, depending upon the environment where you plan to hunt.

 

By Dave McCracken

A good challenge forces you to reach down deep inside and raise yourself to the occasion!

Dave Mack

The yawns being given off by my friend permeated the room so heavily that they clearly placed an uncomfortable shadow over the enthusiasm all the rest of us were feeling. We were on one of the most exciting treasure hunting expeditions I have ever been engaged in, and I was thanking my lucky stars just to be part of the expedition. All of the people involved were very good at their jobs and were enthusiastically involved with this project except my friend. He was bored. In fact, he was so caught up in his own personal boredom, that he was certain everyone else, and the whole world, was also seeing the world in the same mundane way. Talk about being on a different wavelength!

After our planning meeting was over, I gently approached my friend about his outlook. He agreed wholeheartedly with my observation. His viewpoint was because of some unknown factor that he could not quite pin down; he just was not able to take on the project (or life) with enthusiasm like the rest of us.

I asked if someone was sick in his family, or if he had financial or other personal problems that were holding him back. He said there was nothing like that holding him back. To him, for as long as he could remember, he was not able to experience real enthusiasm.

I don’t think any of us can expect to get more out of life than what we invest of ourselves into it. Wouldn’t it be wrong to take more than we give? How can we expect our passion to come from something outside of ourselves?

If we put passion in, perhaps we can get more passion and excitement out of it, whatever the endeavor.

My friend was waiting for some influence outside of himself to give him something to be passionate about. He was looking for some hidden reason why he was not feeling enthusiasm. I suggest that all of this might be a “backwards” approach.

I suggest the impact of life upon us (how we end up being affected by it) is exactly as we choose it to be. If we decide that the way we are going to feel most of the time is due to some (or lack of) outside or hidden influence or the way others have treated us (or not treated us) in the past, naturally, that’s the way it will be for us.

But it does not have to be that way. It can be any way we choose it to be. There are any number of responses we can choose for every given situation.

You do not have to win every battle to be a winner. If you win every time, you are not putting yourself to the real test. That’s not really winning, is it?

You do not have to be “rich” to be successful. Money is not life’s measuring stick.

Life must have worthwhile challenges for life to be interesting. A good challenge requires a fair chance (perhaps even likelihood) that you could fail in the endeavor. Real challenges make you fear the consequences of failing. A good challenge puts you to the real test. It forces you to reach down deep inside and raise yourself to the occasion. It makes you improve yourself. It makes you become more passionate, more brave, more tolerant of others and more secure in yourself.

A real challenge forces you to live life more fully!

I suggested to my friend that perhaps if he took on something more challenging he might discover his own personal enthusiasm. This thought brightened him up considerably.

Some philosopher once said that if taking on something is really difficult for you, try taking on twice as much. Then, the first limit you set for yourself will not seem like too much, anymore. There is certainly some profound wisdom in this philosophy. We do indeed set our own limits for ourselves by the decisions we make or the decisions of others that we agree to.

Ironically, my consistent observation has been that those people who are most challenged in their lives are happiest, most passionate and most enthusiastic even if there is a great deal of pain and misery in their lives. This is true in war-torn Cambodia. It is true in the remote portions of Madagascar where there is no medicine to save a sick child and where people work their guts out just to eat. In all their pain and suffering, those people really have passion in their lives. They are truly thankful for the little they do have. They are happy to be alive today. The few comfortable, good moments really have meaning to them.

“Perhaps we need the challenge of an occasional crocodile in our lives!”

Please do not misunderstand the point I am trying to make. I am not saying that pain and suffering are good. The point I am trying to make is that it is perhaps difficult to experience real passion and enthusiasm in our lives if we are so comfortable that the only adventure we experience is on the television.

Yes, we experience television with a passion. But what about life?

Perhaps, in the end, it is not about rich or poor — or about winning or losing. Just maybe, it is about experiencing everything out of life you can make happen. My guess is that this comes from putting in as much as you have to give. And that comes from being truly challenged in life, maybe even taking some chances.

We each set our own limits for ourselves. If we are not passionately trying to overcome those limits, then maybe we are cheating ourselves out of the best that life has to offer.

We easily forget this lesson in the West, where day-to-day life is not as dangerous as it might be. In many of the Third World countries I have visited, people have to face actual physical dangers in their everyday lives such as crocodiles. Let’s face it; there is not a lot of time to worry ourselves about petty concerns when we are concerned about getting eaten by a crocodile. Perhaps we need the challenge of an occasional crocodile in our lives!

 

 

BY ANTHONY “LITTLE TONY” STEURY, SR.

 

As usual, I awoke to the sound of a mother osprey’s loving shrieks giving instructions to her two young ones who had not yet mastered the art of flight. The sun was just coming over the top of Sugarloaf Mountain, quickly cutting the chill from the night air.

I could tell by the thundering sound of the rapids below my camp that the mighty Klamath River was rising at an alarming rate. The flood gates at the dam were being slowly raised, and I knew my time was limited. I felt that I must get down to bedrock under the rapids in order to find the gold that I knew had been waiting there for a gold dredger with modern equipment since the earth was formed millions of years ago.

As I quickly prepared a hot breakfast to help brace myself for the cold water I would have to endure, I reflected on the past two weeks dredging with my 6-inch dredge slowly moving yards of material, throwing cobbles, and moving small boulders to bore my way down to bedrock and get deep enough to escape the white water force that kept blowing me out of the hole. I was now at a point where most of the turbulence went over the top of my head, and I no longer had to work on my stomach with my face next to the nozzle intake to see. When I first started this hole, I was using 85 pounds of lead around my waist. One slight turn of the head would mean getting my mask or regulator ripped from my face by the turbulent force of the rapids.

I was snapped out of my interlude by the smell of burning bacon and a beautiful eagle gliding gracefully up the river taking full advantage of the thermal river canyon updrafts. Had I known then what events waited for me at the bottom of the river this day, I would have stayed in camp and dreamed of all the gold I had found in the years past.

As I put on my wet suit, my dog “Treasure” was already in the truck patiently waiting to go to our dredging operation as she had done so many times before. I think she knew our time was running out, and swimming the river to work our claim would soon be impossible.

I finished suiting up and grabbed all my gear. Twenty minutes later we were at the dredge, gassing up and getting ready to dive.

I took a quick look at my water marker, and it showed that the water had progressed 18 inches higher since yesterday. Not a good sign in the life of a fast-water dredger. Just as I started my engine and was preparing to slide down the suction hose into my hole, an ominous black cloud came from nowhere and totally blocked out the sun. It gave me a strange feeling as I looked up the side of the mountain and saw the old growth trees bending to a heavy wind by its awesome power. The cold, fast water slammed into my body.

As usual, my gallery was waiting for me in the bottom of the hole. Two ugly eels, three big suckers and many small fingerlings.

Without the sun, and because of a heavy flow of algae, it made visibility less then ten inches. I grabbed the nozzle and started plowing my way deeper around the base of a large boulder that I knew was lying on bedrock. Every day I had tried to move it with an 8-foot pry bar without success. “Today,” I vowed it would move. I threw caution to the wind and felt if I moved enough overburden from around its base, the force of the water would drop it on down behind me to the bottom tier of the rapids.

After steadily working for an hour and a half, I took a quick look at my watch and saw I had ten minutes of gas left. I was just about to go up and refill when the sun came from behind the clouds, allowing me to see that I had finally reached bedrock. There was a one-inch crevice starting at the base of the boulder making it a natural riffle. I took my small pry bar from my belt and pried into the crevice. Yes, I was right! Out came the gold into my suction nozzle. I had found the paystreak; I had outsmarted Mother Nature once again.

Just as I turned to go up and refill the gas tank on my dredge, I heard the familiar grinding sound of falling rock. A breathtaking pain shot up my leg causing me to spin around and grab my calf. As I did so, my mask and regulator were torn from my face. Experienced reflex made me grab my air hose to quickly retrieve my air source which I shoved back into my mouth, blowing out the water so I could breath God’s clean fresh air again.

At this point, after diving rivers and lakes clear back to when I was a young boy, I still panicked, causing me to hyperventilate. My mind started spinning to warn me I was about to black out. From out of nowhere, a voice was telling me to slow down my breathing, lie still and think things out before I became another one of the river’s many victims.

As my mind cleared, I started to run my hand down my leg, since without my mask, I could see only a few inches in front of my face. As I did so, again came the full force of pain which I was now more prepared for. After a quick search, my hand told me my ankle and foot were pinned under the large boulder that I had released with my foolish dredging around its base. I lay back again waiting for the pain to subside. Fighting panic, which would only bring me death, I took off one of my gloves and started to feel around behind me knowing my 8-foot steel bar lay somewhere near-hopefully close within my reach. It was the only chance of freeing myself, and a slim one at that. After groping around as far as I could reach, I was about to give up when my fingers touched steel. I arched my back and got three fingers around the point. Grabbing it the best I could, with my leg killing me, I pulled it toward me far enough to get a better grip and have total control. Just as I got it under and behind the boulder, I heard the engine stop from above.

I knew that there were only fifty-two seconds of air left in my holding tank. I twisted my body allowing me to put my unpinned leg against the boulder while, with arms above my head, I grabbed the top of the bar with both hands. I knew there would be only enough air for one chance to free myself. My mind raced back through my past. I thought of all the sporting events I had won in my youth. All the brave men who had died for their country telling me of all the things they still wished they could do. My family who still needs me and all of life’s battles I had won.

I felt a surge of power entering my body along with that gut feeling one always gets just before a win. I sucked in the last remaining air in my tank, pushing with my leg and pulling down on the bar with the 180 pounds of power that my body had to give.

Instantly, I fe1t the boulder move and I wrenched my leg free. Without hesitation, I ripped open my lead weight buckle release and shot out of the hole and down the rapids at breakneck speed.

In times past, this trip would mean a one-mile walk back up the river along a very rugged river bank, plus a one-hour delay swimming back across the river, floating down to my dredge, and retrieving all the gear I was forced to drop.

This day as my body was bounced along the bottom and slammed into boulders, I felt only the breath of joy while thanking a power greater than myself for this gift of life that was once again given to a mortal such as I. In a matter of minutes, my high-speed float trip was over, after being hurled into a slow water eddy which allowed me to drag myself up on a pile of cobblestones left by the old-time 49′ers.

As I laid back, totally exhausted from the pain and nerve-wracking experience, thinking about the fantastic gold deposit I had located, I looked up into the sky just in time to see my friend the eagle drop a wing tip to catch another updraft. He was, as always, looking after me and all of those who respect and love the river, saying farewell until another day dawned fresh in the life of the fast-water dredger.

 
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By Dave McCracken

“When to do a clean-up”

Some miners like to “clean-up” their sluice boxes after every hour of operation. Some prefer to do clean-up at the end of the day. Others will go for days at a time before cleaning up. This is all a matter of preference and seldom has much to do with the actual needs of the sluice box.

More commonly these days, a dredger only cleans-up the “high-grade” section of riffles in his or her dredge after each sample or at the end of a production day. That is a special small section of riffles which catch most of the gold near the head of the sluice. The full recovery system is usually only cleaned-up when enough gold has accumulated to make the effort worthwhile, or it is time to take the dredge out of the water.

There is a method of determining when a sluice box needs to be cleaned up, so that you can keep it operating at its utmost efficiency. If the majority of gold is catching in the upper-third section of the sluice box, then the recovery system is working well.

After a sluice box has been run for an extended period of time without being cleaned, the riffles will be substantially concentrated with heavy materials behind them. Sometimes an abundance of heavily-concentrated material in a sluice box can reduce the efficiency of the riffles. This is not always the case. Much depends upon the type of riffles being used and how they are set up in the box. The true test of when a set of riffles is losing its efficiency because of being loaded down with heavy concentrates is when an important amount of gold starts being trapped further down the length of the box than where it normally catches. When this occurs, it is definitely time to clean up your box. Otherwise, clean the box when you like.

Expanded-metal riffles, being short, will tend to load up with heavy black sands faster than the larger types of riffles. Still, a large, visible amount of black sand being present is not necessarily a sign that you are losing gold. Gold is about four times heavier than black sand. As long as there remains fluid action behind the riffles, the black sand might have little or no effect upon gold recovery. The best way to evaluate your recovery system is by direct observation of where the gold is being trapped.

DUMPING OFF

The concentrates which have accumulated in a sluice box can be removed by unsnapping the riffles, carefully removing the carpet underlay, and washing everything into a washtub or bucket. The contents can easily be rinsed out of the carpet underlay inside the washtub.

A medium-wide plastic putty knife can be very helpful in removing lingering concentrates from the high-grade section of a sluice box when that is the only place in the recovery system being cleaned-up.

The concentrates can then be screened into another wash-tub or into a bucket, depending upon what type of screens you are using. Classification of the concentrates into several sizes will allow you to process each more efficiently. The size-classifications that you want to use will depend largely upon how you will process the final concentrates. No matter how you process the final material, you almost always want to begin with a ½-inch or ¼-inch screen, just to eliminate all the larger-sized material from your concentrates. The following video segment demonstrates this preliminary screening, reminding you to carefully remove any gold nuggets which stay on top of the screen before discarding the larger-sized material:

There are several types of final clean-up devices on the market which can help you process the final concentrates, including different kinds of wheels, bowls and miniature sluicing systems. They all work pretty well when set up properly. Here is a video sequence demonstrating the use of a gold wheel to facilitate final clean-up:

Each device has its own instructions about the proper classification-size of concentrates for optimum performance. So you will want to buy or make your screens accordingly. The following video sequence demonstrates a second screening through a common sieve about the size of window screen – which is about normal for splitting concentrates into two sizes:

In my own operations, when we accumulate more than just a small amount of concentrates to clean-up, we have had very good results by first running the concentrates through a plastic Le Trap Sluice. First, though, we screen the concentrates through 8-mesh or 12-mesh screen to remove larger material. The following video sequence shows the Le Trap being used to help with a final clean-up:

Or, rather than use a special device (wheel, bowl, etc), you can work your concentrates completely or nearly down to the gold with the use of a gold pan. In this case, I would suggest that you first classify the material through 8-mesh (8 openings per linear inch) and then through 20 mesh (20 openings per linear inch) screens to break it up into three sizes: 1) the material which stays on top of the 8-mesh screen; 2) the material which passes through the 8-mesh screen but stays on top of the 20-mesh screen; 3) and the material which passes through the 20-mesh screen.

Under normal circumstances, the larger two classifications of concentrate will pan down to gold by themselves quite fast. Because of this, even a final clean-up device is usually only used in the field on that material which will pass through the smallest classification screen.

I have thoroughly demonstrated the panning process in a separate article, so I won’t repeat that here.

FINAL DRY SEPARATION

These final clean-up steps can be done at camp, preferably in a dry environment, where the wind is not blowing much and where there is a table top or some other flat surface available to you for a work space.

Important: Before you do the first step of this process, it is best to work your concentrates down as far as possible, to remove all of the black sands that you possibly can. The more black sand you can remove while the material is wet, the less you have to deal with after it is dried. Sometimes you can remove more black sand with the careful use of a finishing pan (small steel gold pan about 6-inches in diameter) inside of a small wash tub.

A Gold Extractor will allow you to work all of your gold down with no loss, and only about a tablespoon of black sands remaining.

Important Note: The best finishing device I have ever seen for working concentrates down to only about a tablespoon of remaining black sand, with zero loss of your gold, is called a “Gold Extractor.” Once your final concentrates are worked down to a very small amount of black sand remaining, you are ready to go on to the next step.

STEP 1: First dry out your final concentrates. This can be accomplished by pouring them into a small metal pan (finishing pan is best) and slowly heating them over an open fire or gas stove-whichever is at hand.

Dry out the concentrates.

CAUTION: Heating the concentrates from a gold mining program should not be done inside of a closed environment. Heating should be done outside and/or in a well-ventilated location, where any and all vapors given off by the various steps will be swept away from you and other bystanders.

You do not want to heat the concentrates too much at this stage. This is because they may still contain some lead. Excessive heat can melt the lead onto some of the gold within the concentrates. Pay attention to heat just enough to thoroughly dry out your concentrates. Be careful that boiling or bubbling during heating is not allowed to spatter gold out of the pan. The following video segment demonstrates this step:

STEP 2: Once the concentrates have cooled enough that they can be handled, they should be screened through a piece of window screen (about 12-mesh). A small piece of window screen, about 6-inches square, is handy to use for this purpose.

STEP 3: Take the larger-sized concentrates (the material which would not pass through the window screen), and pour them onto a clean piece of paper. If there is a lot of this sized concentrate, this step will have to be done in stages, handling a little at a time. Once the concentrates are poured onto the paper, it is easy to separate the pieces of gold from the impurities. The impurities should be swept off the paper and the gold should be poured into a gold sample bottle. This is where a funnel comes in handy.

STEP 4: Once the larger-sized concentrates have been separated, the remaining concentrates can be classified through a finer-mesh screen. A stainless steel, fine tea strainer (about 20-mesh) works well for this. Tea strainers can be found in just about any grocery store.

STEP 5: Take the larger classification of concentrates from the second screening, pour them onto a clean sheet of paper, and separate the gold from the impurities in the same way that it was done with the larger material in Step 3 above.

Use of a magnet on each size-classification of concentrates can be very helpful to remove those impurities which are magnetic.

Some prefer to use a fine painter’s brush to separate out the non-magnetic impurities. Separation can also be accomplished by using your fingers. This step goes faster if you only do small amounts of concentrate at a time. Pour the gold recovered in this step into the gold sample bottle.

STEP 6: Take the fine concentrates which passed through the final screening and spread them out over a clean sheet of paper. Use a magnet to separate the magnetic black sands from these final concentrates. The magnetic black sands should be dropped onto another sheet of clean paper, spread out, and then gone through with the magnet at least one more time. The reason for this is that some gold can be carried off with the magnetic black sands. They tend to clump together. Once the magnetic black sands have been thoroughly separated from the gold to your satisfaction, pour them into your black sand collection. There may still be some small gold values left with them which can be recovered by other methods at another time.

NOTE: There is a really nice set of final clean-up screens on the market that are made just for the purpose of separating your final concentrates into the ideal size-fractions for final dry separation. I highly recommend them, because they separate your final material into multiple size classifications which make the final dry process go even faster.

STEP 7: Now, all that should be left is your fine gold, possibly some platinum, and a small amount of non-magnetic black sand. These final black sands can be separated by blowing lightly over them while vibrating the sheet of paper. Since the sand is about 4 times lighter than the gold, it will blow off the paper a little at a time, leaving the gold behind. Once all the black sands are gone, you can pick out the pieces of platinum if present, and separate them from the gold. Pour the gold into the same gold sample jar used in the earlier steps.

This dry process (Steps 1-7) goes very quickly if an effort was made during the final wet stages to get as much black sand and other waste material as possible separated from the gold.

CLEANING GOLD

Sometimes placer gold just out of a streambed is very clean and shiny. If this is the case with your gold, after the final dry cleanup procedure is completed, your gold is ready to be weighed and sold or displayed or stored away in a safe place.

Sometimes, gold will come out of a streambed with some impurities attached to it. When this happens, it will be necessary to perform a final cleaning process to make the gold’s natural beauty stand out.

If your gold is not clean and shiny, and you want to get it that way, place it in a small non-breakable water-tight jar about half full of water and add a little dishwashing liquid. It does not seem to matter what kind is used. Fasten the top on the jar and shake the contents vigorously until the gold changes to somewhat of an unnatural glittery color. Sometimes this happens quickly and sometimes it takes a little longer. This mostly depends upon how much gold is in the jar. The more gold, the faster the process. This is because it is the friction of gold against gold which facilitates the cleaning process. Once the gold is glittery, rinse the soapy water out of the jar, pour the gold into a small (metal) finishing pan, and heat it up (outside and down wind) until the gold takes on a deep, natural, shiny luster. It is important to make sure that all of the soap has been rinsed away from the gold using clean water before you dry the gold.

Gold has a tendency to turn a dull color after having been stored in an airtight container for an extended period of time. For this reason, some gold miners and dealers store their gold in water-filled jars, and dry it out just before displaying it or making a sale.

If you should happen to store your gold in an airtight container and notice that its color does not seem to be as bright as it once was, wash it with soap and water and re-heat it, as in the above steps. This process will bring back the beautiful color and luster of the gold.

The best time to weigh your gold to get the most accurate measurement is after you have completed all of the final cleanup steps.

SELLING GOLD

There are numerous markets where you can sell your gold. Refineries will pay you for the fineness (purity) of the gold itself and subtract a few percent for refining charges. In this case, you will receive a little less than the actual value of the gold. Refineries usually will not pay for the silver and platinum contained within your placer gold unless you are delivering it in large quantities. Refineries prefer that you bring your gold to them in large amounts. They will often charge less for refining, and sometimes pay just a bit more for the gold, when it is brought to them in larger quantities.

Flakes of gold and nuggets have jewelry value on a different market. If marketed to the right buyers, flakes and nuggets can usually bring in more than a refinery will pay-or sometimes even much more.

If you are in gold country and ask around, you can nearly always find someone who is buying placer gold from the local miners. These individuals usually pay cash. Unless the fineness of the gold within the area is lower than normal, there is no reason to settle for less than 70% of the market-value of the gold for that day. This means that the gold is weighed and the buyer pays you for the weight of what you deliver. Impurities are never calculated into this type of deal. If you enquire around, you can usually find someone who is willing to pay 75% of weight. Sometimes you can find an 80% straight-out buyer-which is good.

There are also people out there who are ready to gyp you out of your gold if they can get away with it. It is wise to bring your own pocket calculator along when dealing with a new buyer.

If you go to a dealer who starts figuring a certain percentage of the fineness, and his final figures end up lower than a straight out 70% of the bulk weight of your gold as it is, go find another dealer. This is not to say that 70% is the going rate. You can do better if you look around. Although, you should never have to accept less than 70% of the going market price for your gold. If a dealer starts to tell you all sorts of reasons why your gold is not worth what you want for it, go find someone else. There are plenty of gold buyers around who will at least admire your gold. So there is no reason to hang around and listen to someone who is trying to steal it from you.

Local miners will know who pays the most! Or go up on our web forum and ask. Someone there is sure to turn you onto a good deal!

Cleaning your gold well before you take it somewhere to be sold can help a lot.

Sometimes dentists will give you a good price for your gold, and a phone call or two can pay off. Also, some lawyers and businessmen like to invest in gold. Sometimes you can get up to 100% of spot for your fines (fine gold) when dealing with them.

Some jewelers will pay well for your flakes when they have a demand for them. It is not uncommon to get as much as 90% or better when you make such contacts.

The best way to get top dollar for your gold is to do a lot of inquiring, always with the intention to find more and better markets. Then, when you need some cash, you can sell to the buyer who pays the most.

 

 

By Dave McCracken

How much you need to qualify a gold deposit in advance depends upon the additional investment that will be required to gear-up for production.

Dave Mack

In placer mining, there are fundamentally two kinds of sampling:

1) Discovery: Attempting to locate a higher-grade deposit of value inside of a larger volume of lower-grade material.

2) Quantification: Extracting and analyzing smaller portions, to gain a perception of how much value exists within a larger volume.

The general concept behind sampling is to minimize investment into a specific mining property, or a particular project, until there is enough proof that a mineral deposit exists which contains enough value to justify a more substantial investment.

The kind of sampling that you should do, and how much is necessary, largely depends upon the ultimate objectives, and/or how large of an investment you will make to implement a commercial project – especially that portion of the investment which cannot be recovered and re-committed to some other project at a later time.

For example, if you are going to join The New 49’ers Prospecting Organization to gain access to 60+ miles of mineral properties in northern California, and decide to devote an extended period of time into searching for and developing high-grade gold deposits along those properties, the money you would spend outfitting yourself with a sampling dredge is something you can depreciate over the extended period. This is because the investment will not be confined to a single mining project or property. When you are done, because the dredge and gear will be accessible, you can regain some of your investment by selling the used equipment.

How much sampling would be necessary in advance of making this investment? Not so much, because most of the investment is not committed to a single mining property. Before a final decision is made, perhaps it would be worth spending a week of your time participating in a Group Mining Project, to obtain some direct exposure to the activity, and see if this is how you want to spend your time.

On the other hand, if you were considering a substantial capital investment to start up a full-scale commercial dredging program on one specific mining property out in the middle of Borneo’s rain forest, where accessibility is only available by helicopter; it would be wise to first send in a sampling-team to confirm the existence of commercial deposits that will allow you to make a reasonable return on your investment. Knowing that most of the capitalization into this kind of mining project is unlikely to be diverted to some other program at a later time, how much sampling would be enough? It should be enough to:

1) Verify that commercial deposits exist on the property; and,

2) Quantify the deposit(s) well enough to become certain that the commercial value of the project is justified.

Sampling is a careful, organized method of attempting to locate high-grade mineral deposits; and then, obtain a reasonable perception of the value they contain.

Here are a few basic sampling principles:

1) The larger the sample, the more accurately the sample results will represent the larger volume of material that has not been analyzed.

2) The more samples you take, and the closer they are together, the more accurately the average result will represent the larger volume of material that has not been analyzed.

3) To achieve an accurate result in sampling, it is vital that you thoroughly clean all of the values from sampling equipment in-between samples.

4) As mineral deposits can be found at different strata’s within a streambed, a good sampling program does not only test in different geographic locations; but also at the different layers within a streambed. This is because it can often be more commercially-productive to mine a deposit only down to a specific strata.

 

On this river in Madagascar, the gold (plentiful) was so fine, the sample material had to be dredged into a large catch basin suspended between two boats, and then processed using specialized equipment on the bank.

5) To be effective, recovery-equipment used in sampling must have the capability of concentrating the values which exist within the deposit. Where special recovery equipment is needed, and the sampling must be accomplished with portable dredging equipment, it is sometimes necessary to dredge the samples into a floating catch-container. Then the samples can be carefully processed on land.

Sizing the gold being recovered, and the gold that is not being recovered, is an important part of a sampling process.


6) Care must be taken to ensure that foreign material is not introduced into the material being sampled which can render the result inaccurate. Just as this has to do with foreign material from other geographic locations, it also has to do with material from different strata’s within the streambed, if layers are being tested independently of each other.

7) The smaller the sample being analyzed, the more the result can be thrown off by the introduction of foreign material (called “contamination.”)

8) Tailings from a sampling recovery system should be carefully analyzed to see what values are being lost; and whether steps can be taken to recover the values in a production operation.

9) Ultimately, only the values that can be recovered during production should be included in the final business projections.

10) Care must be given to measure the amount of raw volume that is excavated to extract a sample. Because the value recovered must be related back to the amount of material that was moved and/or processed to obtain the result. This relation will need to be measured against the volumes and costs associated with a potential production operation.

For example: If an average cubic meter of streambed gravel to be processed will produce $10 in gold (gold at $425/ounce), at a gross production cost of $4 per cubic meter, when a production dredge is operating at 100 cubic meters per day, you can predict a net income of $600 for each dredge participating in the program.

Sampling is generally accomplished in two steps: The first step is to locate the existence of a mineral deposit. Usually, when we use the term “preliminary sampling program,” we are talking about a project where the existence of high-grade deposits still needs to be confirmed.

The second step is to sample the deposit(s) enough to gain a perception of its value. And that’s what this article is really about; how much quantification is necessary? The answer to this question largely depends upon the additional investment that will be required to gear-up for the desired volume of production.

Where we dredge along the Klamath River in northern California, using the very same equipment and support-structure in sampling as we do in production, we do not have to do very much quantification of a deposit before launching into production. This is because just finding the high-grade is reason-enough to mine it. Although, we usually do devote several samples in an effort to find a low-grade area where we can place tailings. Then, we establish the value of the deposit as we mine it.

The reason we can do this, is that under these circumstances, there is no substantial amount of increased financial risk when we transition from sampling into production.

Local miners were recovering rich deposits in the Cambodian jungle using very primitive, low-volume methods. Here was a good place to start with a sampling dredge.

However, many situations are different from this. Some mining projects are just in the start-up phase. Some mining prospects are in remote locations. Under many circumstances, to minimize risk, it is wise to begin with portable sampling equipment to complete the preliminary sampling phase of the program.

Local miners were supporting their villages in Madagascar by digging gravel from the bottom of the river out of boats using long-handled shovels. Our sampling later proved they were digging on the strongest line of gold in the river.

In this case, the question remains how much quantification is necessary to support the evolution to the next level of operations? This will always come back to the program objectives – which often have to remain flexible, depending upon what is discovered during sampling.

Here are several different levels of quantification:

1) Doing enough additional samples to prove that a high-grade deposit justifies bringing in a larger-sized suction dredge to go into production. As part of this, it is important to work out the best type of recovery system to use, and decide how many production-shifts you will run. Night operations require special lighting equipment.

2) Doing enough samples along a stretch of river to prove that high-grade deposits are extensive enough there to justify bringing in multiple production dredges, and setting up a substantial support infrastructure.

3) Doing a series of controlled samples, an equal distance apart, along a portion of a river, to statistically-quantify the value of a mineral deposit. This is often done under the watchful eye of a consulting geologist who will certify the results in preparation for a larger-scale mining operation with the use of mechanized machinery that might float on platforms.

  

 

4) Doing a series of controlled samples, an equal distance apart, for some distance across an entire section of river, to quantify the average-value of the river gravels. This almost certainly would be accomplished under the guidance of a consulting geologist(s) who will certify the results, in preparation of financial instruments for investment bankers or a public trading company.

 

By Dave McCracken

This system combines two classification screens to more-effectively separate material-feed into three separate size-fractions, each which is directed into a different recovery system.

Dave Mack


Riffles in box Three sections of screen

Classification is the Key to Fine Gold Recovery

It is well-established that if you want to effectively recover finer particles of gold, you must first separate them from the larger-sized materials which are being washed through your recovery system by a higher-velocity flow of water. The small-sized material can then be directed to a milder-flow of water over a shorter set of riffles. The smaller you can classify the size of the material, which can be directed by and even milder flow of water over lower-profile riffles, the finer-sized gold that you can effectively recover.

This is all rather easy to accomplish with surface processing plants where earth-moving equipment can be used to feed a plant some distance above the ground. Feeding a plant well above the ground allows plenty of drop for water and gravity to direct material through multiple sizes of classification screens. Then, gravity can be used to direct the different size-factions of material to separate recovery systems with controlled water-flows and riffle sizes specifically designed to recover gold effectively from each size-fraction.

Conventional Suction Dredges do not allow for Much Classification

I am not sure what the exact formula is, but I know from long experience that every inch you lift the feed of a suction dredge above the surface of the water, you lose a considerable amount of suction-power at the dredge nozzle. Therefore, since we have to accomplish both classification and gold recovery from a feed that can only be effectively lifted about 4-to-6 inches above the surface, our options are pretty limited.

Dredge manufacturers have worked out different ways to direct classified materials into slower-moving recovery systems. Generally these methods fall into three categories:

1) Placing a classification screen over top of a set of riffles. This way, smaller-sized material can fall through the screen into a slower-moving flow of water over riffles that are more-protected from higher-velocity water-flow. You see screened-over riffles in common use today.

2) Placing a classification screen towards the head of the sluice box, and then directing the classified material to one or two completely separate sluices which have a slower-moving flow of water over lower-profile riffles. This was most commonly seen in the form of side-by-side triple sluices during the 80’s and early 90’s. While effective, the problem with the side-by-side sluices is that the side sluice(s) normally have to be placed on top of the dredge’s pontoons. Therefore, in order for gravity to make everything work right, the initial feed to the dredge has to be lifted higher out of the water. This causes a power-loss at the nozzle. So you do not see as many side-by-side recovery systems in production on suction dredges these days.

3) Placing a classification screen somewhere towards the upper-end of the recovery system, and directing the classified material to a slower-moving recovery system which is located directly below the main box. This is commonly referred to as an “over-under recovery system, and remains in popular use today. An over-under system is most commonly accomplished in the same basic sluice box, which is constructed with a removable false bottom. By this, I mean two separate recovery systems, one sitting over top of the other, in the same sluice box.

I cannot go into which of these systems are better or worse; because there are too many variables in play, and experienced prospectors can work it out to get the best recovery possible out of any of these designs, each which would likely be comparable to the other. That’s because all three of these system concepts depend upon a single classification screen to remove some portion of the smaller-sized material from the higher-velocity water-flow which is required in a dredge.

This particular discussion has more to do with the effectiveness and size of material-classification. Remember, with conventional suction dredges, we are using water-flow to move all our material across any classification screen(s) that we are using. The larger the dredge, the faster and more powerful the water-flow must be to wash larger-sized rocks and a larger volume of material through the sluice. The faster the flow, the less time that smaller-sized material has to drop through a classification screen. The smaller the openings in the screen, the less opportunity smaller-sized material has to drop through the screen. The shorter the screen, the less opportunity smaller-sized material has to drop through the screen.

Each of these factors combine into to the effectiveness of the dredge’s classification. For example, the substantial flow of water to move 5-inch sized material over 10 inches of 1/8th inch punch plate does not present much opportunity for minus-1/8th material to drop through the screen. So while a separate slower-moving recovery system might be doing a better job recovering smaller-sized gold, perhaps the classification system is only allowing 5% of the finer-sized gold to be directed into the slower-moving recovery system. In other words, the effectiveness of your recovery system is largely affected by how you are attempting to classify and separate the smaller-sized material.

Therefore, on the subject of fine gold recovery with suction dredges, our first challenge is to try and accomplish effective classification as best we can out of a strong flow of water (strong enough to move the largest rocks you are sucking up through the recovery system).

Years ago, we overcame this whole challenge on commercial dredges by working out a mechanized shaker screen at water level which provided 100% classification of the dredge feed. Minus-sized material from the screen was dropped into a sump where it was redirected by a gravel pump to an elevated feed on a surface-type recovery system either on the shore, or on a separate floating platform.

But it is impractical and too expensive to try and place a mechanized classification screen on smaller-sized dredges — which also must remain more portable for sampling. Therefore, on conventional dredges, until someone comes up with something different (if ever), we must continue to make due with a water-flow to wash material across our classification screen(s). With this in mind, here are a few principles which I believe to be true:

1) The faster the flow, the more difficult it is to drop finer-sized material through the openings of a screen in your sluice box.

2) The smaller the holes in the screen, the less finer-sized material you can expect to drop through the openings out of the high-velocity flow required to move larger material through your sluice box. Example: Using the same flow of water and material, you could expect more fine-size material to drop through a 3/8-mesh screen, than a 1/8-mesh screen. This is because the larger openings provide a bigger doorway for material to drop through.

3) The shorter the length of a classification screen, the less fine-sized material you can expect to drop though. Therefore, we want the classification screens to be as long as we can get away with. Longer screen means more opportunity for finder-sized material to drop through.

4) Effective classification of finer-sized material can be accomplished better in stages. For example, first drop 3/8-minus material out of the fastest flow in the box. Then, using a slower flow of water, direct the minus-3/8 material over a 1/8-inch screen.

5) Since we only have 4 or 5 inches of drop to work with from the feed of a conventional suction dredge, there is only room for two levels of classification screen before we must drop the finest-sized material into a recovery system. Otherwise, we will be underwater where reduced gravity is not going to allow water-flow to work for us, anymore.

What to use for a fine-gold recovery system?

material in rifflesAs I have explained elsewhere, I believe it is necessary to direct finer-sized material over lower-profile riffles that will continue to remain fluid under a mild flow of water, even when they are full of concentrated (heavy) material. If you have not reviewed the theory on this, I strongly suggest you read “The Size of Riffles.”

There are different kinds of low-profile fine gold recovery systems on the market. Just take a look around and make your own choice.

We have been using the green, plastic Le Trap sluices to reduce the volume of our dredge and high-banking concentrates all the way back to the early 90′s. I cannot overstate how effective these Le Trap Sluices are. When set up with the proper water-flow, a Le Trap will recover all the visible gold from a feed of minus-1/8th material with losses that are so minimal as to be meaningless. We know this from panning the tailings hundreds of times over the many years.

So when we needed something to recover overwhelming amounts of fine gold using a dredge on a river in Cambodia, I started giving a lot of thought to how we could more-effectively classify dredged material down to minus-1/8th, and direct the material in a controlled flow over Le Trap-type riffles.

Dredge 1Dredge 2

Several very experienced dredge-builders and I created the prototype several years ago from a Precision 6-inch dredge. To accomplish our objective, we assembled two layers of classification screen, each which could be independently raised or lowered, so that we could adjust the water-flow over the riffles, and over each of the screens. The top screen is 3/8-inch mesh. This is to allow the larger-sized material and strong water-flow to wash through the box without affecting the plastic riffles along the bottom. Minus-3/8ths material drops through the top screen onto a 1/8th-inch mesh screen, where the water flow is substantially reduced. Slower water-flow then allows finer-sized material more-extended contact with the 1/8th-inch screen.Double screens over riffles

Material that drops through the 1/8-inch screen is then carried over the Le-Trap sluice by a mild flow of water. By adjusting the height of the lower screen over the plastic riffles, and the slope of the sluice box, we are able to control the amount of water-flow over the lower-profile riffles.

Since the sluice box in the 6-inch Precision was much wider than a normal Le Trap sluice, the prototype required quite a lot of work in a cut and paste project (using of 4 or 5 Le Traps) to create the first underlay recovery system for a dredge.

Fine goldWe invested quite a lot of time and energy into the prototype. All you have to do is look at how much (very fine) gold we found on that river in Cambodia to understand why we did it. We were shipping this 6-incher over to resume (sampling) where we had left off on that earlier project.

 

During trials on the Klamath, I was amazed at how much (very) fine gold we recovered out of just a minute or so of dredging loose material off the surface!

Our trial run on the Klamath River near Happy Camp in March several years ago turned up so much fine gold out of the lose surface gravel, that I hesitated over sending the 6-inch prototype to Cambodia!

I have been told for 30 years that there is so much fine gold in the river that we are losing out of our conventional dredges, if we could just recover it, we could make the river pay just by pumping any gravel! This new system seemed to prove that theory may be true, especially with these higher gold prices. But it was March and the Klamath was cold; so we shipped the original prototype dredge to Cambodia.Cambodia Dredging

I devoted plenty of time in Cambodia (underwater) observing three separate flows of material coming off the back-end of the recovery system; and it was poetry in motion!

I have a non-disclosure agreement with our clients in Cambodia, so I cannot go into details or images of how well the new system performed over there. But I can say that I devoted a lot of time underwater watching water and material exit the sluice box in three separate flows; and the double-screen system is by far the best thing I have seen on a conventional dredge for effectively classifying material into three separate size-fractions.

Because of that, my experienced buddies and I invested quite a lot of time during the 2009 mining season to adapt the double-screen system to my 8-inch dredge. 8-inch dredge

Building double classification screens, so they can be adjusted up and down to allow you to set three separate water-flows through the sluice box, requires quite a lot of labor! But getting this right is the foundation of this whole concept.

Here are some video links which demonstrate the system being used on my 8-incher. These give you a much better look at how we created a double-screen classification system over top of the fine gold recovery: Take a look at the size of the gold we were recovering!

 

As (bad) luck would have it, the State of California imposed a temporary ban on suction dredging just as we completed the double-screen refit on my 8-inch dredge. This forced us up onto the Rogue River in Southern Oregon, where we are limited to smaller-sized dredges. So my 8-incher had to be set aside.

Picking up on the idea of my double-sluice conversion over a plastic sluice, one industry-fabricator was recently promoting the idea of refitting conventional sluices (using the plastic sluice underlay) which do not include the double-screen classification, and do not allow the screens to be adjusted. I would advise caution on short-cutting these concepts. That is what prompted me to write this article. Since these conversions must be accomplished through custom shop work, I wanted to provide you with some background so you can make your own decisions.

While there is still a lot to learn, for the reasons I outlined above in points 1 through 5, I personally do not believe that you can classify raw material effectively from a 4, 5 or 6-inch (or larger) dredge being washed across an 8-mesh screen by high-velocity water.

I believe effective classification must be accomplished in stages; first to drop the 3/8-minus material out of the higher-velocity flow which is needed to push the larger-sized material through the sluice. Then, drop the 1/8-minus out of the much slower flow necessary to wash 3/8-inch material across the lower screen.

I believe you have to be able to adjust the height of each screen (set the water velocity) in order to get a workable water-flow over the riffles and over the 1/8-mesh screen. The water-flow cannot be so much that you boil-out the riffles, and it cannot be so little that you load the riffles. You also must not pack up the space between the two screens!

Eric Bosch and I first experimented with this double-screen concept in the early 90′s. But we made the mistake of fixing both screens (welded them where we estimated they ought to be). Our estimate of how much water-flow was needed between the screens was incorrect; the space between the screens packed solid with material; and the whole system failed.

Also, if you cannot adjust the water-flow over the riffles, and between the screens, you cannot compensate for different conditions in different areas.

Dave's goldAs an example, there is an overwhelming amount of heavy black sand and small iron rocks (and lead) along the Rogue River in Southern Oregon. We do not encounter this magnitude of heavies on our properties along the Klamath River in northern California. The heavies along the Rogue completely overwhelmed my fixed recovery system (buried the riffles on my 5-inch conventional dredge) at the beginning of last season. This prompted me to place smaller riffles below my (fixed) screen, spaced further apart. That worked better, and I recovered a lot of gold. But I believe I lost most of the (very) fine gold (I could see it in the last riffle) that was fed into my sluice box. This has prompted me to refit the recovery system on one of my 5-inch dredges for the upcoming season.

The images at the beginning of this article show an early version of the double-screen system that was designed for deposits we located in Cambodia. We did not find a single particle of gold on that river that was larger than the size of a pinhead. Since larger-sized gold was not present, we did not want to waste the (very) limited amount of room we had to work with by installing riffles for larger gold. Those images are helpful in showing the plastic sluice underlays (there are two of them, one following the other).

The images at the beginning of this article show the Cambodian version of the double-screen refit. Those images are helpful in showing the initial plastic sluice underlays that we were using (there are two of them, one following the other).

Header areaHeader with screen and miners moss

The images in this article also show a header section near the upper-end of the box. My initial theory was that the initial impact of the water and material must bottom-out on something other than plastic sluice underlays. We experimented with a combination of different kinds of heavy screens over top of miners moss or ribbed rubber matting to absorb the initial force of the water and material where it bottoms-out at the head of the sluice box. Fortunately, nearly everything we have tried in the header section seemed to work really well. As you will read below, we have since evolved completely away from using plastic sluice underlays… Header area after running

This is what the header area looked like under the screens when we shut the dredge off while dredging at production speed. You can see how classified material kind of mounds up there before flowing onto the slick plate of the riffle system. We are finding that quite a lot of (very) fine gold also gets trapped in the header section!

We have noticed that while in production, material tends to mound on top of the header section under the 8-mesh screen, and then wash off the mound onto the first sluice underlay. This is really good, as long as the mound does not rise up and pack-up the whole space between the screens.

While we were still using them, the plastic sluice underlays followed just behind the header section. This allowed water-flow and material to settle out and slow down before being washed across the lower profile riffles.

 

 

 

Two kinds of rifflesriffle section

Notice that the shorter section of riffles (remains protected by the top screen) are present only to process classified material which washes across the 8-mesh (lower) screen in the box.

Adding larger riffles for bigger gold

We have since evolved the system, adding two sets of different-sized riffles to catch larger-sized gold. We accomplished this by replacing one of the 1/8-mesh (lower) screens with a solid bottom that supports both sets of the added riffles. The false bottom continues to allow an under current to wash minus 1/8th material across a low-profile underlay, just like in the Cambodia version.

The first set of riffles on top of the false bottom is designed to process the material that drops through the 3/8-inch screen, but is too large to drop through the 1/8th-inch screen (1/8th-to-3/8th size-fraction). This would be for small nugget-sized gold. That size-range of gold is very easy to recover.

As I discussed in The Size of Riffles, the height of a riffle necessary to recover a piece of gold normally does not need to be much taller than the size of the gold you are trying to trap. So the first set of riffles for larger gold can be rather short. Notice that the first set of riffles continues to be protected by an extension of the top screen.

Then we added a final set of open riffles (not covered by a classification screen) to catch any gold we might suck up that is larger than 3/8th-inch (larger nuggets). For example, depending upon where you dredge, the Rogue River in Southern Oregon can produce a lot of gold in these larger sizes. But the river is loaded with fine gold, as well.

It is kind of hard to see in the images; but if you look close, you can see the plastic sluice under the false bottom where we placed the riffles for larger gold.

Since you cannot buy these double-screen systems ready-made, you either have to refit your own sluice, or arrange with a capable fabricator to do it for you. With this in mind, I will follow with some basic directions which we have learned from building several of these systems:

Building the System

If you look at a Le Trap, you will see that it has 3 important sections: There is a slick plate at the top. This is vital; because it allows the water-flow to smooth out before material encounters the riffles. Then there are some short riffles. These capture all the gold unless you over-feed the box with too much material at once, or unless you completely fill the short riffles with gold. Then there are some deeper riffles which more-aggressively capture all the rest of the gold when you do over-feed the short riffles up front. “Overfeeding” has more to do with the amount of heavy iron material, than light sand or gravel. I will talk more about this down below.

Close-up of rifflesThis image shows two sluice underlays following the header section (with no screens on top)

When we planned these sluice underlay riffle-panels, we included the slick plate up front, and then went about 50/50 the rest of the way using short and deep riffles. We did this because I wanted more of the short-type riffles that work so well in the Le Trap. But I did not want to eliminate the deeper riffles which create such a strong back-flow, especially at times when lots of material is being fed across the box. But through extensive trial and error using the third evolution of this system this past season, we discovered that the higher velocity flows that are necessary to move volume-amounts of classified material across the plastic riffles were also causing some of the trapped fine gold to boil out of the system. Too bad! We then tried Keene’s new ribbed rubber matting (good stuff!) and ended up with the same result (we were losing some gold). So it appears that these plastic and rubber riffle systems are better suited for final concentrating work, rather than being used in the volume production setting inside of a dredge recovery system (more on this below).

Because the double-screen assemblies are heavy, in order to manage them, you have to divide your sluice box into several smaller sections. How many sections depends upon how long your sluice box is. You will notice in the images at the top of this article that we divided my 5-inch dredge into three separate sections. One section is over the header area. The other two sections are over top of two identical sluice underlays. It is wise to divide the sluice underlay sections into exactly the same sizes. This way, the parts can be interchanged when it is time to reassemble your recovery system.

We build the double-screen assemblies so they rest exactly upon the sluice underlays. This allows us to take apart one only portion of the sluice box if that is all we want to look at or clean-up.

The screen assemblies are built so the aluminum side supports slide down inside the sluice box and sit directly on top of the side rails of the sluice underlays. This pins everything down snuggly against the bottom of the sluice box. Then we snap the screen assemblies down tight to make sure everything stays in place when we are running the dredge or moving it around on land or in the river.

Sluice Underlays

Close-up of matting
Close-up of both

Through a very substantial amount of trial and error this past season, we discovered that both the plastic sluice material and also the new Keene rubber matting were losing gold from under the twin screens.

Expanded metalWe finally found the right combination by using a wide, raised expanded metal over top of deep ribbed rubber matting. The aggressive expanded metal was dropping the gold out of the classified feed. Once it was in the ribbed mat, the gold was not getting away. This combination was so effective, we even replaced our header section with the same expanded metal, though we used miners moss underneath, rather than ribbed rubber matting.

We did multiple checks; and we were never able to find a single speck of gold in the final 25% of our recovery system, even though we were mostly dredging in fine gold pay-streaks (loaded with fines in the front section of the recovery system) all season.

This is important: The width of the sluice underlays (and screen assemblies) have to be a bit narrower than the inside of your sluice box. Otherwise, it is too difficult to get them in and out when you want to perform a clean-up or reassemble the recovery system. I always allow a margin of around 1/8th or 3/16ths of an inch, maybe even ¼-inch on a wider sluice.

Note: We have since replaced the sluice underlay in the drawing above by welding some 3/4-inch angle iron on both sides of the expanded metal to create side rails that the double-screen assemblies can rest on top of.

The following video sequence should give you a better idea of what we have ended up with as a sluice underlay:

The width of your side rails needs to be greater than the margin you are allowing between the sluice underlay and the side of your sluice box. This is so you will be sure that the sides of the screen assembly are going to slide down and meet the rails of the sluice underlay.

Double-screen Assemblies

Sliding the second screen into the frameThese add up to some weight; so you have to plan how to divide your sluice box into small-enough sections that you can lift the screen assemblies out of your sluice box without too much trouble. On the other hand, you want to minimize how many sections you have to make, because these are very labor-intensive to build.

The length and width of the screen assembly should match the sluice underlay, so that they will marry-up exactly when you set the screen assembly down on top of the underlay.

 

Screen LatchYou have to use aluminum plate for the sides to keep the overall weight of the screen assembly from adding up too much. The height of the sides needs to be at least as tall as your sluice box. I build mine high enough that I have room to adapt a latch to snap everything down tight.

Once you have the aluminum sides of your screen assembly cut to size, bring them all to your local machinist, and ask him to mill slots so that you will be able to raise and lower your two screens. If you bring the machinist one of the lag bolts you are going to use, he can mill the slots just wide enough to allow the lags to slide up and down freely, but not so wide that the lag is allowed to turn in the slot when you are tightening or loosening the nuts that hold the screens in place. Just to make sure I will have the full range of adjustment, I have the slots milled nearly the full height of the sides, to within about ¾ inch of the edge, equally at the top and the bottom. Each aluminum side needs three slots; one on each end and another in the exact middle.

You can source thin-headed lag bolts from fastener supply outlets. If you look, I’ll bet you can find them on line. If you cannot find them, then you have to grind the heads down on regular lag bolts, because normal heads are too thick and will take up too much space between the screens and the sluice box.

Helpful hint: The head-thickness of lag bolts on both sides of the screen assembly need to be included when you are deciding how wide your screen assembly and sluice underlay need to be for everything to slide in and out of your sluice box without too much difficulty.

Another helpful hint: If you cut the side plates all the same size, and have the machinist mill the slots exactly the same on all the plates, all the pieces will be interchangeable, and then you can jig-up to drill standardized holes in the side rails to your classification screens.

The lag bolts need to be heavy enough to support the weight of your screens (perhaps 5/16ths or 3/8ths). Different boxes have different widths, meaning heavier screens. It is better to go a little heavy on the lag bolts. The bolts need to be long enough to extend through the aluminum side, through the side rail of the screen, and have enough room for a flat washer and self-locking nut.

Screen frameStacking screens

Ideally, you build all your screens exactly the same size, so they can be interchanged. We accomplish this by rigging up a jig to cut all the side rails exactly the same; then to weld the frames all the same; and then to drill all the bolt holes the same. We drill the bolt holes in the side rails a little large to allow some margin for error.

Side rails for the screens need to be heavy enough to support the weight of your screens with you standing on top of them. By heavy, I am discussing rail thickness. Because, if you go too wide, you will limit how close you can adjust the distance between the screens. Thicker 1.25-inch-wide strap has worked well on my refits for the screen side rails.

Unless you want to buy whole new sheets of screen (expensive), I suggest you source used screen at your local metal scrap yard. The one we go to in White City, Oregon nearly always has a large supply in all mesh sizes. I gather that commercial screening plants replace their screens pretty often – most of it still in good enough condition to meet our needs.

The top screen (around 3/8th-inch openings) needs to be heavy enough to span the length and width of your screen assemblies without needing additional support, and without bending or sagging when you stand on top of the finished screen.

The lower screen (around 1/8th-inch openings) needs to be heavy enough to span the length and width of your screen assemblies without needing additional support.

Helpful note: I experimented with a finer-mesh lower screen (about 1/10th-inch openings), and had trouble with small particles of rock plugging up all the holes. We call this “blinding.” It’s when the holes in a screen all become plugged-up (or overwhelmed by too much feed), preventing the screen from doing its job. So it would appear that you do not want to use a mesh on the lower screen much smaller than 1/8th-inch.

Cutting screenWe have had good luck cutting the screens to size using a cutoff wheel on a hand-held grinder. If your side rails are made of thick material, you should be able to cut the screen to size and weld it down directly on top of the side rail frame. Grind all the edges nice and smooth, so your hands are not getting cut up once you start working with these screens on your dredge.

Helpful note: If you weld the bottom screen on top of the side rails, and the top screen on the bottom of the side rails, you will be able to loosen or tighten the center bolts in the side plate much more easily. I am talking about the lag bolts which attach the screens to the aluminum side plates. If you end up with your center bolts between the screens, it is much more difficult to get at them!

Another helpful note: You might want to drill your holes just off center through the side rails. This way, you can still get a socket on the nuts after the screen is welded on.

These helpful notes are things I have learned the hard way!

When you assemble the screens, a good starting point would be so that the bottom screen rests maybe just a little more than an inch above the plastic sluice.

Helpful hint: If you make the side rails on your sluice underlay too tall, it will limit how far down you can slide your lower screen.

We have had pretty good results lifting the upper screen about 1.25 inches above the lower screen.

This is important: To add more flexibility, if not already present, we modify the sluice box supports on the dredge so that we can raise and lower the slope of the box. This creates a very helpful mechanism for adjusting flow rates.

Once in the field, you can make adjustments to sluice slope and height of each screen to work out the needed velocity in three separate water-flows: First, the water-flow across the sluice; then the water-flow between the screens; and finally, the water flow across the top screen.

I already discussed above how to replace the lower screen with a false flat bottom which you can place riffles on top of to recover the larger classifications of gold. In my view, it is more effective to do this in the lower section of the sluice box (though, I mounted the riffles for larger gold in the upper-end of the sluice on my 8-inch dredge). I know this viewpoint is not popular with some prospectors, because they do not want to chance losing a bigger piece of gold that is allowed to get so close to the end of the recovery system. My answer to this is that gold is really heavy stuff! If there is some anomaly (like the gold is attached to quartz rock which makes the piece lighter) that would keep it from trapping in a set of riffles in the back-end of the box, it probably will not drop out in the front portion of the box, either.

Other than in a very rare occasion, the vast majority of the gold you will recover is small enough to drop through an 8-mesh screen. Some important part of that gold is so fine as to be difficult to recover using the recovery system on a conventional suction dredge. The journey of fine gold through 20 feet of suction hose, and then up through a diffuser (flare jet) places most of this fine gold right on the bottom of the material as it first flows into the sluice – right where you want it; right where it is most likely to drop through the classification screens out of the higher-velocity flows, which otherwise can wash it through your box like sand. Better, I think, to get the minus-1/8th gold into a safe holding area as the first priority.

If you look closely at the diagram just above, you will see another reason to put the larger riffles towards the rear-end of a double-screen system. See how all or most of the fines are directed through an undercurrent below the larger riffles? This means the larger riffles will not be getting flooded and loaded up with fine-sized material. So, while fine material gets more exposure to low-profile riffles (where it belongs), the deeper riffles remain more open so that larger gold has a place to drop out of the flow.

But that is just my view. You guys can do it any way you decide to!Riffles just after shut-down

The reason you see rocks on top of the double-screens, is because we turned the dredge off while we were pumping at production speed. See how the riffles are working? They are not loading up, and they are not boiling- out. This means the system was working!

I do my classification and sluice flow adjustments when running the dredge at normal operating speed while I am feeding the nozzle at production speed in hard-packed streambed. I arrange for a second person to kill the motor without notice. Then, when I disassemble the system, I can see how the sluice and screens are performing while I am pumping gold and gravel into them at production speed.

Between these explanations, the drawings above, the images and the video segments, you guys (or the fabricator who will help you) should be able to see how these systems come together, and how they work. They provide you with a whole lot more than I started with!

Here follows a video segment we put together at the end of this last season which demonstrates the most recent evolution of this very effective dredge recovery system:

Other Considerations

Trial runPossible need for added floatation: As I mentioned above, these double-screen assemblies are heavy. So if you do a refit of your sluice, you may also consider adding some floatation to your dredge. When I refit the original 6-inch Precision dredge for Cambodia (image above), I also had new, larger aluminum pontoons made up to provide enough floatation so that I could also stand on the dredge while it was running. Nice!

Having enough water-flow to make double-screens work: Every dredge is a bit different. Before refitting your dredge with a double-screen system, you might turn the dredge up and watch the water-flow across your existing recovery system and estimate if you will have enough water volume to provide sufficient velocity to meet the needs of three separate flows.

Overfeeding the system: Every recovery system has its volume-limits! Since I find nearly all of my high-grade gold associated with hard-pack, I design my recovery systems to process average material which makes up normal hard-packed streambed that was put in place during the evolution of a major storm event. Normal streambed consists of rocks which are fitted together, with smaller rocks and pebbles in-between, with gravel, sand and silt filling the smaller spaces. When taking apart normal hard-packed streambeds, the smaller-sized material only comprises a small fraction of the overall volume. Therefore, I have yet to overwhelm one of these double-screen systems while production-dredging in hard-packed material.

On the other hand, if you go out on the river and just start pumping sand or loose, classified gravel (like tailings), a much-higher percentage of the material will penetrate the screens and you will almost certainly overload (blind) the sluice with too much material – and perhaps even pack-up the space between the sluice and the bottom screen. Let me be clear: This double-screen system is not designed to process sand or loose gravel deposits or tailings from some earlier mining activity!

This same concern is true for any type of recovery system used on a suction dredge. So it is important for you to be mindful of the material that you are feeding into your suction nozzle. If it is a layer of sand or loose gravel, you should either slow down; or you can speed up and pump it through as fast as you can; and then go up and make sure your system is no longer packed-up before you start feeding pay-dirt into your dredge.

The fine gold needs to be present: The only good place to test the effectiveness of your recovery system is when you are feeding high-grade into your dredge. The more gold you feed into the recovery system, the better you can see how well it is working.

Effectiveness cannot be discounted just because you see a speck or two of gold down towards the end of your box. The thing to look at is where most of the gold is stopping.

So many times, I have watched others decide their recovery system is not working, only because they are not recovering much gold. You cannot recover much gold if it is not present in the streambed that you are dredging! So I suggest you reserve judgment until you test your system in high-grade.

 

 

BY PAUL BADALI

Since we’re still in the mainstream of the dredging season, I’ve decided to share a few tricks I’ve picked up in my experiences with dredging over the past few years. Hopefully they will help to make your dredging a little easier.

After several seasons of use, dredge hose becomes cracked and needs to be replaced. I have tried to repair the cracks and holes in my 5-inch yellow hose with silicone R.T.V. glue, that didn’t work; so I knew I would be replacing it. The only 5-inch hose I could find in the dry desert state of Utah was a very light duct hose called Spirolite, which is used to blow insulation into attics. The hose is so light and thin that I decided both the first and second time I went in to purchase some it could not hold up under dredging conditions. But the price was so good (about $3.90/foot for 5-inch) that I finally bought a 10 foot length just to see how it would hold up in the Klamath River. I liked it so well that when Tony Dilmore, who had originally recommended it to me, showed up in Happy Camp with some, I bought another 20 foot length from him.

Spirolite has definite advantages in some dredging applications. First of all, it is extremely flexible. It is ideal for creek dredging where the hose often must be wrapped around boulders. Secondly, it is extremely lightweight weighing only about half what the yellow hose weighs, so it’s easier to pack down the bank or into remote dredging sights. It does not show excessive wear as I had feared it might. When I first looked at this hose, I pinched my thumb nail and finger nail together on the thin clear material between the spiraled ribs and was able to pinch a hole in it. But I can’t see any holes in my 20 foot section of hose after half a season’s use in the Klamath River. So, it seems to hold up well. It does develop small holes where it is clamped to the nozzle and the jet, but these areas are at the end of the hose and can easily be cut off when they get bad. And at $4/foot, you can afford to take this into account and buy five feet more than you need. And as for beating out plug-ups, you don’t have to. This hose is so flexible that it rarely plugs-up. If a rock does turn sideways and plug, you simply deform the hose with your hands, and the plug frees with no hammering on the hose!

There is one application where a heavier, stiffer hose is preferred over the Spirolite, and that is in deep or fast water. Because the hose is so light and flexible, the water can grab it and keep pulling it out of your hole. When I used this hose in the gut of the “Glory Hole” on the Klamath in about 15 feet of water, I had to keep the dredge near the edge of the river, use 30 feet of hose, and anchor it to the bottom at two points on the way out into the gut. The nozzle still washed out each time I went up to knock a plug out. But for calmer more shallow water, it’s the hose I prefer to use.

You should be able to get it at most large hose supply stores in larger cities. If they don’t recognize the brand name Spirolite, ask for the lightweight clear spiral duct hose they use to blow insulation into attics with, and get prices at three or four hose supplies. You may get it even cheaper than I did!

Has your swivel nozzle stopped swiveling after two seasons of use? Mine had. Sand and small rocks work their way down into the joint, and rust accumulates in there over the winter. But if you have access to an arc welder, the repair job is simple. Just cut or grind off the weld beads that hold the swivel joint to the nozzle, and remove the swivel joint. Inside you will find two rubber O-rings or pieces of rubber cord cut to work as O-rings. Pull the whole assembly apart, and use a wire brush to buff rust and sand off of all the metal parts. Clean the rubber cord or O-rings in water.

You want to catch any sand that falls out, and pan it. I found one nice flake of gold inside my nozzle when I cleaned it. You may wish to use some type of non-oil lubricant in the swivel joint before you reassemble it, such as graphite or silicone. I haven’t done this yet, but I suspect graphite is the way to go.

To reassemble, simply match the old ground-off beads back up, and tack it in the same spots with an arc-welder. I would not gas weld these beads, as I suspect it would get the rubber O-rings too hot and damage them. When you are done, your nozzle should swivel as good as new. While you have the welder in hand, touch up any wear you see elsewhere on the nozzle.

This last winter, I got about 26 feet of 36-inch-wide miner’s moss free! You may be able to do the same. I noticed that miner’s moss was used on the floor as mats in every entrance at a local high school. I found the janitor and asked if he would keep me in mind, and give me any old pieces he might be throwing out in the future. He was curious as to why I would want old mats, and we got into an hour’s discussion about dredging for gold. At the end of our chat, he said, “You know, I think we have a few old pieces we’re throwing out in a store room right now.”

We went to look, and he helped me wheel out three six-foot pieces, and one eight-foot piece of miner’s moss. They needed some cleaning up, but hanging the carpets on the kid’s swing set and using the garden hose soon took care of that.

The moral of this story is ASK. If you want something, ask. If you think people will say no, nine times out of 10, then just ask 10 people, and you’ll get what you want. Everyone has seen miner’s moss being used for foot mats. The U.S. Postal Department uses it, supermarkets do, banks do, etc. They all have to throw out the old and replace it with new. So ask for the old mats, and chances are you will get some!

I would also like to give some advice on moving your small-size dredge around on a big river like the Klamath. If you are not a good swimmer, and you are scared to death to swim across; then listen to your intuition, and stay on the side you’re already on. Know your own limits, and don’t get yourself into trouble. But, if you’re an average swimmer, and just a little apprehensive, then here are some tips on getting yourself, the dredge, gas supplies, and concentrates back and forth across the river without a boat.

Number one, buy a good set of fins. Good fins fit over your wet suit booties and are fairly stiff. They are not so stiff that they feel like cedar shingles, nor so soft that you can touch the tip of the fin to the heel, but somewhere in between. With a good set of fins, you have about as much power in your legs as a 2-hp outboard motor, and you can really cruise across that river! Always wear your wet suit without weights when crossing, and take it easy. If you’re not used to pumping fins, you can quickly get a leg cramp from over exertion.

The current will pull you downstream as you swim. Pick a calm stretch of river to swim across, and start way up stream from where you want to end up. Don’t choose a calm spot immediately above bad rapids, because if you don’t make it, you will be going for a very bouncy ride. If you are crazy like I am, this can be lots of fun, but it can also freak out your wife who watches the ride from shore!

To swim across, just float on your back, point yourself towards the other shore, and pump your legs. Don’t try to head up- stream and fight the current! Just start way upstream from where you want to land on the other side, and take a relaxed ride. The fins do all the pushing, just let your arms dangle. With fins and a wet suit on, it’s easy as swimming in a lake.

To take my dredge across, I load everything onto it, and push on the tail-end of the sluice box while kicking with my fins. I do not like a rope tied from the dredge to the shore. I do not swim a rope across first, and let that rope pull the dredge in. I play outboard motor with my fins, and I propel the dredge to the other bank. I lie on my stomach if pushing, or on my back if pulling. I feel much more in control of the dredge this way. I do choose a very calm stretch of river to do this, and I give myself twice the distance upstream that I think it will take to get across. It’s easy this way for one guy to get a dredge across by himself, and it’s a breeze if you have a helper also wearing fins.

Supplies and concentrates are also easy to get across. If you use a large 30-gallon tub to dump your concentrates into, you already own a small boat. You can put your weight belts, winch, tools, towels, etc. into the tub, and pull it with you as you lie on your back and kick across. It will sink if you tip it, and an inflated inner tube around the tub adds safety and more buoyancy. You can pull people in dry clothing across in a small rubber raft as fast or faster than they can paddle. You can also very easily swim a motorized sluice (high-banker) across the river in a small raft or an inner tube. You can fit lots more cargo in a rubber raft if there is no one in the boat! Obviously, when you want to come back across the river, you have to walk upstream; because you will be washed downstream as you swim back across.

There really isn’t much to fear from a big river if you are careful. You float like a cork in a wet suit. Don’t fight the current! The current is stronger than you are, so “go with the flow,” and let it work for you. Get good fins, so you have some push, and have a good time with it. In most cases, there has been less prospecting and mining done on the other side, so you may reap great rewards for your investment in a pair of good fins!

Good luck, and see you out there!

 

BY SAM LONG

 

Dry-washing, in many ways, puts me in mind of eating at a Chinese restaurant with chopsticks. It’s fun to try; but you can’t move material from one place to another very fast, even if you’re good at it. That’s why it’s so important to pick out an area with a theoretically high concentration of gold. Of course, down here in Arizona, you’ve got about as much chance of finding an area like that as a one legged man’s got at winning a kicking contest!

That’s not to say you shouldn’t try. I always do so with this theory in mind: Billions of years ago, when God was putting tons of gold in Alaska, South America, Russia, Australia, the Yukon, and even California, he accidentally spilled a couple of pounds over Arizona. I always think of that after I’ve worked through a pile of rocks and sand big enough to shade an elephant, and not come up with enough gold to fill a tooth. All the expert mining techniques in the world won’t come up with a speck of gold where there’s none to begin with. So, the place to start is history.

I know you’ve read it a thousand times. Now you can say you’ve read it over a thousand times: It’s usually better to begin your search for gold in an area that has produced it in the past. The more the better.

From that point, go to maps. Study them religiously. I take my topographical maps to an office supply that has an enlarging copier. I have the section I’m interested in blown up two or three times. This really helps in seeing all the side washes, forks, bends, and places of slowing water that are the obvious holding spots for gold.

Now, you’re ready to hike to these areas. Of course, on your way to and from these spots, keep your eye open for any likely looking area you might have overlooked on your map. There are a zillion of them, so you’ve got to learn to be very selective.

Remember, you want to shovel rocks, sand, and gold through your dry-washer, not just rocks and sand. It doesn’t matter to your shovel. It doesn’t matter to your neighbor. It only matters to you. Take your best shot before you ever crank up your machine, and you won’t have to deal with the disappointment of getting skunked.

And, just how do you do this? Sampling. That’s right— sample, sample, sample. If you’re diligent about it, and do it correctly, when you finally start dry-washing, your question won’t be will I find gold? It will be how much will I find?

Starting up your dry-washer in a likely-looking spot without sampling, makes about as much sense as a dog barking at a knothole. Sure, sampling is a lot of extra work and it takes time. But, when it’s all said and done, you’ll end up with some gold along with the new blisters–instead of a sour attitude and the new blisters.

This isn’t to say you can’t set up anywhere and get some color. But to my way of thinking, that would be pure luck; and I haven’t experienced enough of that to feel qualified to write about it. If you have, and can make it work time and time again, I’d sure be willing to learn.

So, here we are in a gold producing area, walking up a wash that had some likely-looking gold-holding spots on our map. How do we sample? Well, as with most things, there is more than one way to skin a cat. I use a Goldspear. It’s proven itself to me to be an accurate, time saving, prospecting tool. I know lots of folks don’t think much of them, but usually they haven’t ever owned one, or don’t understand how to use them to their advantage. Granted, they’re not some super tool that can automatically find gold. But used correctly, they can sure save you a lot of needless digging. And, at the price of shovels these days, you don’t want to wear out any more than necessary.

For now though, I’ll skip the use of the spear and explain a few points of how I sample without one. Again, this isn’t the only way to sample or dry-wash, but it works for me. Adapt it to your own personality and tools, as you see fit. In my pack, my basic tools are: Two pans, a small kitchen sieve; and, because we’re prospecting dry washes, a wide-mouth plastic gallon jar of water. Needless to say, never go anywhere without your rock pick.

With these basic tools, slowly work your way up the wash, visually sampling as you go. In your mind’s eye, continually look for the places gold is likely to accumulate. The more of these types of places you can recognize, the more success you’ll have in sampling.

Likely gold-holding areas would be the inside of sharp bends; areas where the wash levels and widens, indicating slowing water; areas of red and blue clay; pockets of iron pebbles, which show the water’s inability to carry heavier minerals; or a zone of magnetite, hematite or quartz. All these are good visual indicators that gold will likely be present.

After finding a place containing as many positive indicators as possible, roll over the biggest boulder you can in that area; and using one pan to hold the water, screen some material from under the boulder into the other pan and go to work. If you’ve done your homework right, this should yield you a few colors. Jot down how many on your map at the place where you found them. If more than just a few colors materialize, try a couple more pans before moving on. Continue in this manner for the rest of the day. You should have a few different areas that are somewhat better than the others.

Now that you’ve picked a good spot to work, and packed in all your equipment, the last important point is the speed at which you run the material through your dry-washer. It’s a big temptation to drop your riffle board too low so you can process material faster. But by doing this, you’ll lose a lot of finer-sized gold. As you either know, or will soon find out, most gold in the dry washes is very small. Unless you keep your riffle board only slightly lower than level, a good portion of the fine gold won’t have time to settle. It will end up going over the end instead. You can’t feed any more material in than is going out, so be careful not to overfeed the hopper. Otherwise, you’ll end up with gold in your tailing pile. Nothing will make you feel ankle high to a frog in a post hole quicker than your neighbor coming by, to run his Goldspear through your tailing pile, and getting enough beeps to make a liar out of you, when you tell him you were planning to run it through again a second time anyway.

The biggest hindrances to running your machine are laziness and rain. If you’re the type who does more spitting on the handle than shoveling, you’ll probably welcome the rain. If not, the folks around you will surely think you were raised on sour milk. It takes the fun out of dry-washing when you just get going good, then it rains and stops your operation. That’s what happened to us this winter. With my Keene dry-washer, I could work wetter dirt than everyone else because it blows hot air. But after the fourth cloudburst, it was even too wet for me. We switched it to a re-circulating water system and kept going.

So, if you pick the right spot and don’t push your machine, you’ll get some good gold. It might not be the most gold you’ll ever get in a day, but that desert-gold is some of the prettiest you’ll ever find. Since gold is more ornamental than useful anyway, you ought to be happier than a fly in a raisin pie

 

By Jimmy Sierra

“What goes on in that metal box may be a mystery to most of us, but we all know it isn’t magic”

 

Metal detectingThe title of this article can mean different things to different people and thereby add to the mystique surrounding the entire field of metal detecting, for that is what “Electronic Treasure Hunting” is all about. The word electronic should mean the same to everyone. What goes on in that metal box may be a mystery to most of us, but we all know it isn’t magic.

The vast assortment of transistors, resistors, capacitors and various integrated circuits add up to a very sophisticated type of transmitter which broadcasts a signal through the transmitting coil of copper wire contained in the disc or loop at the front-end of the detector. This signal is affected by the electromagnetic field which is present around all metal objects. Thus, when it returns to the receiver-coil in the loop, this signal is changed. The change is interpreted by the complex circuitry in the detector box and lets us know that there is metal out there.

Depending upon the sophistication of the detector, this data can include the possible type of metal, depth of the item and even the shape or identity of the metal object. This may be an over-simplification of what goes on, but we need not worry about how it happens. Let the engineers who invent these devices handle that. The thing to remember is, metal detectors find metal. There are variables that create differences between detectors, and these variables will determine which style of detector is best-suited to the type of treasure hunting that we wish to do.

This brings us to the second part of the title of this article: Treasure Hunting. As I mentioned, this is the part that means different things to different people. To some, it means looking for dropped coins or jewelry in various places such as parks, playgrounds, backyards, beaches, picnic grounds or even old ghost towns. The locations change and the technique for searching varies a great deal, but the basic function of the detector to locate metal is the same. Some consider treasure hunting to be locating caches of buried coins or valuables, even sunken galleons. Again, the treasure and the location change, but the detector is still operated as it is de- signed, to locate metal objects.

To others, treasure hunting takes the form of searching old battle sites or ghost towns for relics of days gone by.

And yet, another select group of treasure hunters who call themselves “prospectors” direct their search for the elusive nuggets of gold, long sought by man to be used as a measure of wealth.

By now I hope it has become apparent that the common denominator linking most treasure hunters together is the electronic metal detector. The location may change and the targets may differ, but all respond to the initial function of the detector to find metal. It is only necessary to vary where we look, and to some degree, develop special skills unique to each type of treasure in order to change from coin shooter to cache hunter to relic hunter to prospector.

This might be a good time to clear up one particular misconception, one that has been brought to my attention hundreds of times over the years by those unfamiliar with treasure hunting. That is, the idea that metal detectors cannot find GOLD. This stems from some misunderstanding about the nature of gold. When I have questioned these people, I have found that most were not really sure if gold was a metal or not. Some had a vague idea that gold might be classed as a mineral. Most, however, were not sure what the difference was between a metal and a mineral.

In brief, the difference between a mineral and a metal is that a mineral is a chemical compound of more than one element, and a metal exists in its pure state as a single element. So, let’s just accept the fact that iron, copper, lead, silver, and GOLD are all metals and can be found free in that form, and that all of them can be located with a metal detector. We can surely begin to see why such mystery surrounds gold and gold prospecting, as well as treasure hunting in general.

I do not mean to imply that electronic treasure hunting or prospecting is as easy as falling off a log; only that it is not magic, and that the skills acquired while learning to hunt coins in a park with a detector are the same skills used when prospecting for gold nuggets in the Mohave Desert. The target and the location change, but the basic skill is only varied by the different types of hunting.

Up until several years ago, one of our most successful coin shooters from the Sacramento area in California had never seen a gold nugget except at the various gold shows where suction dredgers show off the treasures which they find at the bottom of streams and rivers. He had acquired the necessary skills over the years in the operation of his detector. He had learned to utilize the ability of his detector to cancel-out the ground mineralization caused by iron ore and salts which mask the ability to locate metal objects such as coins. He had trained his ear and slow searching techniques to hear those deep older coins. When he decided to give a shot to gold prospecting, he had little else to learn. He was successful right from the start. Of course, he didn’t look for the nuggets in the local park. But, he did find his first nugget in a dry streambed not more than 15 minutes from his house. He was bitten by the gold bug on that first day and will never be the same!

His biggest problem was to find a good place to hunt. He rightly concluded that the best place to start was where the old 49ers had found gold. If it was there then, it was surely there today. He was right. He began by going over the tailings left behind by old-timers. Gold was plentiful and the old methods of recovery were not perfect. Carelessness and lack of skill left plenty behind. He researched old maps and history books to seek out previous diggings. Sometimes, he went over old tailings. Other times, he searched dry washes and gulches near the diggings. Experience sharpened his skill and techniques, just as those many hours spent in the old parks had prepared him for this new approach to treasure hunting.

Averaging three days per week searching, he found more than 40 ounces of gold last year!

I do not want to paint too rosy of a picture here. The fellow mentioned above is a real experienced detectorist. He spends time hunting and looks for the right spots. Few of us will measure up to his success. But most who try their hand at treasure hunting will be pleasantly surprised at how fast they can become skilled in the use of this electronic device. Practice and patience are all that are required. Skill in tuning and operating the detector comes from reading the manual carefully and asking information from the dealer that sold the unit. Other users are a good source for acquiring special helps in learning to use the unit. I, as well as others, have written articles and books explaining in detail the tuning and searching techniques of metal detecting.

Joining up with others in a Club or association will gain you very valuable access to experience and places to hunt for golden treasure.

One of the unpredictable ingredients in the creation of a successful treasure hunter is LUCK!! The old adage that you have to be standing over a target to find it, is true. My friend and I were searching an old baseball field a number of years ago which was adjacent to an old Mission. We both found numerous coins, many silver, but all from this century. I was lucky enough, however, to find a 1778 Spanish half real dating back to the Mission Period. It was only 4 1/2 inches or so deep. It was luck. I was practicing the same learned skills as my partner and we both were successful. My old coin was there because I was standing over it.

I have a good friend with whom I prospect. We dig a lot of targets in order to find the elusive gold nugget. I have found many nuggets, most in the tiny-to-small size-range, but none really large. However, along with many smaller nuggets, this fellow has found a 6-ounce, a 9-ounce, and a 12-ounce piece of Mother Nature’s natural golden treasure. Granted, he hunts for gold nuggets a lot more than I do, but many who hunt as often as he does never find nuggets in that class. Wouldn’t you say some luck came his way? Each one of these nuggets was found with a different make and model of detector.

Many detectors are pretty equivalent in ability to find metal, but all metal detector users are not equal in skill — or in luck.

Another example comes to mind at this time: This one might seem pretty far-fetched, but it is true. A few months ago, a prospector-friend of mine called to announce that he had just found his largest nugget to date. It was a ¾-ounce piece, that’s 15 pennyweight. Now, that is a respectable nugget. Of course, he said he found it with the help of his faithful dog. You might call the dog his gold-hound at this point. While my friend was prospecting along the bank of a popular river, his dog was doing his duty near the water. As he noticed his dog scratching at the sandy shore, he caught a glimpse of something flashing in the sunlight. He went closer to investigate and spotted the aforementioned nugget with loop and all attached. Some luckless prospector had lost his prized specimen from around his neck. One man’s loss is another man’s gain, as they say. It goes without mention that this is one dog that will never want for attention again!

We have talked about learning how to use the detector, regardless of what the object of your search is. There is no substitute for expertise and skill. We have mentioned that buying the proper detector is essential and we have pointed out that a certain amount of good luck doesn’t hurt. The final ingredient is good old perseverance and perspiration.

My basic intent in this article is to clear away some of the magic from electronic metal detecting and show it as an acquired skill, which is what it really is. It is important to buy the best detector you can; one that has the ability to cancel the ground-mineralization. This is most important if you plan to use the detector for prospecting, because gold and silver are most-often found in highly-mineralized soil.

If you are going to use the detector in trashy areas (lots of man-made metal objects), you should buy a detector that has some ability to identify trash. Otherwise, you will have to dig every target that sounds off. This is not only tiring; but since you can only dig so many targets in a day, it diminishes the odds of digging good targets. You can see that this would not be important if you were relic hunting, where all items are potential treasures. But it is more important when coin hunting, where pull tabs and bottle caps are not desired, or in prospecting, where nails and tin cans left from former miners are tedious to dig and not as valuable as gold nuggets. Of course, if the area is virgin, one would not have a need for identifying trash.

Being able to identify a “hot rock” (a rock with different mineral content than the surrounding terrain) is also an important feature to be looked for in a detector to be used for prospecting. Have your dealer help you pick a detector best-suited for your needs, whether they be specialized or multi-purposed.

Good Hunting!