null signals with VLFs

[bcfromfl]

Hi everyone —

I’ve been sitting here at home, going absolutely stir-crazy because I’ve had to delay my prospecting trip to the PNW due to high river levels still from el Nino. I’ve had years of experience coin-shooting with detectors, but this will be my first experience nugget-shooting for gold. I’ve been familiarizing myself with my new Gold Bug Pro, mostly with some tiny, odd-shaped lead targets I’ve clipped from squashed air rifle pellets, weighed and recorded using my digital scale, and folded into pieces of duct tape.

A few months ago, I buried an old corroded copper wheat penny at exactly 12 inches in my backyard, with the intent of allowing it to develop a halo for testing. I thought I was beyond the capabilities of the GBP, and right after burying, there was no signal. No response after a few months would give me an indication of the limits of the machine.

Yesterday, I went back to it, and discovered it was now giving an obvious “null signal.” To say I was surprised is an understatement! Enough metallic ions from the copper had escaped into the soil to enhance the signal for the machine to react. I’d never seen such an obvious demonstration of this phenomenon.

My question is this: will gold nuggets do the same? I know there are geologic theories now about secondary gold enrichments occurring on the ionic level, as the atomic bonds will begin to decompose in acidic conditions, allowing the ions to redistribute. I Googled a bit and came up with a couple hits on message boards with respect to null signals, nuggets and PI machines, but nothing on VLFs in all-metal. What sorts of experiences have you all had out in the field? I plan on digging everything, but if I need to be especially alert to null signals, I’ll have my ears at the ready.

Thanks!

 

Amazon Forum Fav 👍

DR.ÖTEK Metal Detector, Waterproof Gold Detector, Pinpoint & Terrain Modes, Professional Metal Detector - Grab it through Amazon!

[Hoser John]

Lousy zinc pennies corrode and break down much faster than any non ferrous metal. Gold does not-John

 

[adamBomb]

Here is an explanation from Tom Dankowski about what really happens here:

"The longer a metallic item is in the ground........... the more compacted the dirt....... in general...... around that object. This allows a much better 'electrical connect' with the ground. The metallic object is more 'grounded'. If the object leaches into the ground........... the 'electrical connect' with the ground is greater. It is not the oxides that provides a better/larger detection of the object............ rather............... it is the fact the metallic item is well grounded...... allowing better detection.

Too much emphasis is placed upon the 'halo'. More focus needs to be placed on the enhanced 'electrical connect'. "

 

[bcfromfl]

Thanks very much for both your responses. So, pieces of gold perhaps beyond the ability of the machine to make a positive response won't ever cause a null signal? I'm always listening for soft zip-zips?

I don't have the reference at my fingertips, but there have been experiments with gold nuggets in acidic soil. Carefully weighed beforehand, left in place for several months/years, then recovered and re-weighed. The nuggets become lighter, but when the surrounding soil is collected and processed for microscopic gold, the recovered amount equals the weight that the nugget itself lost. Could this result in what detectorists call the halo effect?

Thanks very much for the quote from Dankowski. I realize my question contradicts what he writes about...just trying to understand better those null signals in all-metal. It sounds like if I dug up the penny, re-buried it, and wetted and pounded the soil on top, I should get the same result immediately without having to wait several months? (BTW, the penny I used is a copper wheatie.) Regardless, getting a response from the GBP at this depth on a marginal target is encouraging!

 

[adamBomb]

It sounds like if I dug up the penny, re-buried it, and wetted and pounded the soil on top, I should get the same result immediately without having to wait several months?

It would be worth testing to find out. From everything I have read, when the item is well settled into the ground and wet with no mineralization, it will then be as deep as an air test on the same item. So technically you could air test this penny to see what the max depth is going to be. There are cases however where it can be different than the air test. For example detectors with automatic ground balance can be affected if there is no ground and also unknown interference in an air test, from things such as EMI/RF can skew the results. Here is another tom d quote on figuring this all out:

"Bad = Freshly buried or 'turned' soil. Target not electrically 'connected'.
Better = Target in compacted dirt for many years.....in natural setting..... and in good 'contact' with dirt.
Best = Airtest. No dirt minerals. Many variables removed. "

The reason I have all of these quotes is that I keep a journal of MD stuff as I learn the technology so I can pull it out when needed.

 

[trinityau]

Hello, I just happened to see this thread on the Gold Bug Pro. I tested the GB Pro, several models before it came out, and I am very satisfied with the great performance this unit offers. I even devote an entire chapter in my new book "Detecting for Gold, Adventures, Trips and Tips" to the Gold Bug Pro. There is information also on my website "TRINITYAU.COM" along with lots of other great information pertaining to Gold Detecting. Air tests are just that, "air tests". Air tests have proven completely worthless to me over the forty or so years I have been detecting. There are way too many variables. The halo effect and other information that was offered may have some effect, I don't know. I have my own idea's about that subject. I will tell you that I have found nuggets with the GB Pro from twelve pennyweight down to about one pennyweight at depths reaching twelve or thirteen inches, in very hot ground and with a great signal response. There are many dedicated gold detectors on the market, but for the money and simplicity of operation I don't think a person could go wrong with the Gold Bug Pro.

 

[meMiner]

I am a user and not a tech, but here is my "two cents":

I am impressed with your testing, I am sure it will be valuable so you can "hit the ground running" when you get into the field.

For sure, I need to do more testing and evaluating too. It seems every time I go out, I learn something new (or worse, relearn). I switched machines recently and only after my second trip did I realize that I was ignoring signals that had the potential of being something wonderful. I am not a "dig everything" kind of guy, until I isolate the micro locations that have high potential. Too often, I have exhausted myself digging countless holes in a marginal spot when I should have focused my attention somewhere close by (and then I run out of time). I am not suggesting that anybody adopt my approach...

The test on the coin was interesting, but possibly irrelevant. There are way too many other factors affecting response from the detector. For example, there are different compositions of wheat cents, depending on the mint and date. Typically, they were 95% copper, but at the end of WW2 they were made from aluminum from recycled shells. Heck, there were some Lincoln wheat cents (very valuable) that due to an error were actually steel slugs. So there might be a halo effect, but what is the oxidization mineral in the halo? Even "gold" nuggets are not normally pure gold, so the halo effect could be from the gold but more likely from the other metals within the nugget. I used to think that I was experiencing a halo effect when I dug a target and the signal went away when the ground around the target was disturbed. Maybe. I now think that more often than not, it was either junk, the target dropped to the bottom of a deep hole while digging or I had multiple small targets that separated when digging.

For sure moisture content of the ground affects detectors (I think more than a halo effect), but even this is not simple. Is the ground evenly saturated with water? Or perhaps, it is dry on top and damp a few inches down? Or is it the other way around (after a rain), where the top is wet and deeper is dry (this one is horrible for some detectors)? One fellow that I knew swore detecting was better during a full moon - - I don't think so, but it sure gave him confidence.

A null response, that is repeatable, is not typically something you want to dig. Your detector is telling you something may be there, but it is probably not worthwhile (eg. hot or cold rock). Either that or your detector is confused, which happens quite a bit, especially on deeper targets.

 

[bcfromfl]

Thanks so much everyone for your awesome responses!

It would be worth testing to find out. From everything I have read, when the item is well settled into the ground and wet with no mineralization, it will then be as deep as an air test on the same item. So technically you could air test this penny to see what the max depth is going to be. There are cases however where it can be different than the air test.

I ended up digging the target, just to make sure I was interpreting the signal correctly...and also because my wife had just tripped over the stake and I wasn't exactly sure where it was any longer! I'll re-bury, and try compacting the soil to see if I can replicate the results immediately.

It's raining pretty hard right now outside so I can't test the penny in question (it's next to the hole), but I pulled out another wheatie to do an air-test and came up with 8.5". It could probably squeak out 9", but it was pretty faint, and not necessarily repeatable.

That's great that you save all those quotes and relevant detecting info! Very helpful, and much appreciated!

Hello, I just happened to see this thread on the Gold Bug Pro. I tested the GB Pro, several models before it came out, and I am very satisfied with the great performance this unit offers. I even devote an entire chapter in my new book "Detecting for Gold, Adventures, Trips and Tips" to the Gold Bug Pro. There is information also on my website "TRINITYAU.COM" along with lots of other great information pertaining to Gold Detecting. Air tests are just that, "air tests". Air tests have proven completely worthless to me over the forty or so years I have been detecting. There are way too many variables. The halo effect and other information that was offered may have some effect, I don't know. I have my own idea's about that subject. I will tell you that I have found nuggets with the GB Pro from twelve pennyweight down to about one pennyweight at depths reaching twelve or thirteen inches, in very hot ground and with a great signal response. There are many dedicated gold detectors on the market, but for the money and simplicity of operation I don't think a person could go wrong with the Gold Bug Pro.

Thanks so much for chiming in, Ray! I bought your book several weeks ago, and have read it through several times. (Hmmm...about time for another go-through!) My favorite chapter is "A Golden Summer." I hope I can have a fraction of the success you have had over the years! During my planned trip, I'll be covering bedrock along rivers in sections alongside where hundreds of ounces were recovered with dredges, hydraulic tailings that have never been detected, some forgotten mine dumps in the hills, and even try an afternoon or two looking for pockets.

The test on the coin was interesting, but possibly irrelevant. There are way too many other factors affecting response from the detector. For example, there are different compositions of wheat cents, depending on the mint and date. Typically, they were 95% copper, but at the end of WW2 they were made from aluminum from recycled shells. Heck, there were some Lincoln wheat cents (very valuable) that due to an error were actually steel slugs. So there might be a halo effect, but what is the oxidization mineral in the halo? Even "gold" nuggets are not normally pure gold, so the halo effect could be from the gold but more likely from the other metals within the nugget. I used to think that I was experiencing a halo effect when I dug a target and the signal went away when the ground around the target was disturbed. Maybe. I now think that more often than not, it was either junk, the target dropped to the bottom of a deep hole while digging or I had multiple small targets that separated when digging.

Thanks for your observations, placergold! You may be right about that penny. After I dug it up, I realized that I hadn't noted the reading on the LCD scale, or the possible iron content. (I used a Garrett ADSIII for my coin-shooting back in the '80s, and am having trouble getting used to a screen to look at. I'm accustomed to just depending upon my ears.) It probably would have been better to bury a nickel, and maybe I'll try that too. The wheatie was too badly corroded on the face to determine exactly the date, but I think I arrived at either 1945 or 1946. It definitely wasn't a war-era penny...I wouldn't do that!

Clearly I've got more familiarization to do. I've read about nugget shooting newbies not finding any gold, because they're looking for typical, perfect signals, which apparently you only rarely get. I thought I might be onto something with this null signal, but maybe I'm just going in the wrong direction. The lead targets I made are helpful, but not so much for testing at the limits, because they always seem to give a recognizable, repeatable signal no matter the orientation. I've read that gold pieces can be a little persnickety sometimes, and it's these marginal signals I'm trying to prepare myself for.

Thanks again for all the help!

 

[63bkpkr]

Hi bcfromfl,
The prospecting spot you mention sounds like the perfect place to test out some of Lanny's metal detecting bedrock thread about finding gold in solid rock.

I took his advice to heart and found gold in "solid rock". Actually for me what happened was that the bedrock was actually fractured allowing small gold flakes to work their way down the crack some six to eight inches. I have found gold with my Whites GMT though it took me a good amount of time to learn the machine and to train myself on how to use it (I think this is the case with any brand machine for any detecting purpose). It takes time to learn how to use the machines so practice an extreme amount as it will pay off in the long run. "Solid Rock" hits, where your detector is telling you there is gold there, can be of at least two types - a buried pocket or crack (where pounding rocks have sealed the pocket/crack) or where a crack is not easily visible. What I've seen in NorCal is that a bedrock crack will be hidden by a fine line of green growth (moss, etc.) so for that purpose I carry a very thin/flat (old) nail puller. Insert the thin pry edge of the nail puller into the crack and bang on the top of it with a rock/hammer/stick/whatever and most of the time the broken off piece will jump right out of place. These fine flakes sound out really well on my GMT and every tiny bit of gold adds up so keep it all.

Best of luck with your adventures..................63bkpkr

 

[bcfromfl]

Hi bcfromfl,
The prospecting spot you mention sounds like the perfect place to test out some of Lanny's metal detecting bedrock thread about finding gold in solid rock.

I took his advice to heart and found gold in "solid rock". Actually for me what happened was that the bedrock was actually fractured allowing small gold flakes to work their way down the crack some six to eight inches. I have found gold with my Whites GMT though it took me a good amount of time to learn the machine and to train myself on how to use it (I think this is the case with any brand machine for any detecting purpose). It takes time to learn how to use the machines so practice an extreme amount as it will pay off in the long run. "Solid Rock" hits, where your detector is telling you there is gold there, can be of at least two types - a buried pocket or crack (where pounding rocks have sealed the pocket/crack) or where a crack is not easily visible. What I've seen in NorCal is that a bedrock crack will be hidden by a fine line of green growth (moss, etc.) so for that purpose I carry a very thin/flat (old) nail puller. Insert the thin pry edge of the nail puller into the crack and bang on the top of it with a rock/hammer/stick/whatever and most of the time the broken off piece will jump right out of place. These fine flakes sound out really well on my GMT and every tiny bit of gold adds up so keep it all.

Best of luck with your adventures..................63bkpkr

Hi 63bkpkr -- thanks so much for your suggestions and recommendations, and well-wishes! Yes...it took me a few weeks...but I finally made it through Lanny's thread. What a source of knowledge for all sorts of great experiences in gold country! I bought a small fishing tackle box to put in my backpack, and in it I've put all sorts of crevice tools, but can't fit all of the various possibilities, so I hope I won't get out there and need the one that I couldn't fit! I'll also have a small pick and also a rock hammer hung on my carpenter's belt. Some of the locations I've mapped out will be steep, so I've also got climbing rope and gear. It'll be challenging to swing the detector while I'm trying to get the rope around trees, but it will hopefully put me in some good spots. Tons of mining history in the area.

Thanks for your reminder about those crevices that get pounded closed. That was a really interesting observation of Lanny's, and the fact that you've found success with it as well, really is encouraging!

The thing that concerns me the most are those marginal signals I keep reading about -- the ones that people decide against digging, and someone goes along behind them and cleans up. I don't know what they sound like (I thought they might be like the null signal I had), and wish there was a way I could replicate them while I'm practicing. Soon, I'm going to be boxing up most of my gear...including the GBP...and mailing to a staging location closer to where I'll be traveling, so I'll no longer have the opportunity to experiment with the machine. I'm excited about the possibilities of being in places where metal detectors have never gone, and I don't want to blow it!!

 

[goldenIrishman]

My thought on this is that if you're just going to be in the PNW on vacation, I'd skip those signals that are really questionable and concentrate on the signals that show more promise. Now if you were living in the area and had all the time you needed, sure, dig everything that gives you a signal of any sort. Since you've only got a limited amount of time you'll need to make the most of it. If a signal is on the borderline, then maybe dig a little and see if it improves but don't waste all day chasing a signal that doesn't improve with a little digging.

 

[bcfromfl]

My thought on this is that if you're just going to be in the PNW on vacation, I'd skip those signals that are really questionable and concentrate on the signals that show more promise. Now if you were living in the area and had all the time you needed, sure, dig everything that gives you a signal of any sort. Since you've only got a limited amount of time you'll need to make the most of it. If a signal is on the borderline, then maybe dig a little and see if it improves but don't waste all day chasing a signal that doesn't improve with a little digging.

Thanks for the advice. You're probably right...I've got a lot of locations to check out in two weeks, and am maybe a bit ambitious in what I expect I can accomplish. After a bit of time out in the field digging actual targets, hopefully it won't take me too long to dial in what's good and what's a pass.

 

[Gold Itch]

First off Gold does not have a Halo effect and the signals you are looking for are the faint ones, Anyone can find the Blaster but the ones they miss are the faint signals that only just break the threshold or cause the threshold to rise or drop out, Use headphone and go low and slow Gridding the area, If anyone is digging just the medium to loud signals then they are leaving about 85% of the nuggets in the Ground maybe more,

If you get a very faint signal or a rise in threshold Do a boot scrape and see if the target gets better or dig down until you get a good signal, If it is Iron walk On, if the target stays good DIG, if the Target is suspect Dig, All this stuff Is Day One of Nugget Hunting School, So do what I have written in this paragraph and Maximize your Chances,, And if you still want Proof copy what I have said and go and ask Steve Herschbach or any of the full on Guys.

Send me a PM and I will find you some useful links, Ok,

Good Luck,, John

 

[bcfromfl]

First off Gold does not have a Halo effect and the signals you are looking for are the faint ones, Anyone can find the Blaster but the ones they miss are the faint signals that only just break the threshold or cause the threshold to rise or drop out, Use headphone and go low and slow Gridding the area, If anyone is digging just the medium to loud signals then they are leaving about 85% of the nuggets in the Ground maybe more,

If you get a very faint signal or a rise in threshold Do a boot scrape and see if the target gets better or dig down until you get a good signal, If it is Iron walk On, if the target stays good DIG, if the Target is suspect Dig, All this stuff Is Day One of Nugget Hunting School, So do what I have written in this paragraph and Maximize your Chances,, And if you still want Proof copy what I have said and go and ask Steve Herschbach or any of the full on Guys.

Thanks John! I've been doing a lot of Googling over the past few months, and I think what was confusing me was that some of the posts on messageboards were talking about PI machines (that sometimes dip or "null" over deep targets), like what I experienced with the deep penny. However, I could swear I read somewhere that a deep, marginal piece of gold -- like one on edge or something -- will sometimes break the threshold briefly on a VLF machine, like a "quiet signal." Can't trust my memory any more!

I really appreciate your experience, and also everyone else's who does this regularly. You did mention a couple of marginal signal types: "...just break the threshold or cause the threshold to rise or drop out." This sounds like what I'm asking about, like a "quiet signal." Am I understanding this correctly?

I've got a pair of NuggetBuster NDT headphones. They're a little awkward and heavy -- we'll see how it goes.

Thanks again!

 

[Gold Itch]

Thanks John! I've been doing a lot of Googling over the past few months, and I think what was confusing me was that some of the posts on messageboards were talking about PI machines (that sometimes dip or "null" over deep targets), like what I experienced with the deep penny. However, I could swear I read somewhere that a deep, marginal piece of gold -- like one on edge or something -- will sometimes break the threshold briefly on a VLF machine, like a "quiet signal." Can't trust my memory any more!

I really appreciate your experience, and also everyone else's who does this regularly. You did mention a couple of marginal signal types: "...just break the threshold or cause the threshold to rise or drop out." This sounds like what I'm asking about, like a "quiet signal." Am I understanding this correctly?

I've got a pair of NuggetBuster NDT headphones. They're a little awkward and heavy -- we'll see how it goes.

Thanks again!

Sometimes all you need is that waver/Drop/Rise in the threshold to tell you there is something down there,

You have about the best headphones there are with the NDT's whether they are Nugget Busters or the Grey Ghosts or the Whites Prostars they are all the same except the GG's have the noise limiter built in, So rest assured there is nothing better so you are safe there,

Time for some Sensible Air Testing, Set your machine up as before and plug In your head phones and get some small test pieces and wave them in front of the coil and see if you can remake the signals that you think you heard, Whether they are fainter or a little stronger, This will Train your ears to recognise faint signals that are out of normal detection ranges and do it when ever you are bored or have time on your hands because over the years we develop some bad habits and unless the signal blasts out ears off or is strong enough to give us a VDI reading we tend to walk away, So learn then Wavers / Drop outs and when that happens out in the field do a Boot Scrape or take a couple of inches off the top and if the signal gets louder keep going until you can ID the Target,

If your detector has what is called "Mixed Mode Audio" that is where you get a high tone for a good target and a low tone for Iron and then you get a thing what is called a Third Tone and that is where it won't give you a HIGH tone or it won't give you a Low tone because it is deeper than the ID range of the Detector and the Detector will give you a combination of the 2 sounds mixed as ONE and This "Third Tone" can and will fade to something that can be a Rise in threshold or a nulling or just a slight Waver in the threshold, The MXT is a Classic when it comes to Mix Mode Audio because it does it in all 3 modes,

This Mix Mode Audio can ADD up to 35 to 45% more depth on targets, IE a Quarter at 12.5 inches can make the Third Tone signal out to about 19 to 21 inches which is about a 55% increase depending on how well you have Tuned your Ear to recognise such signal, This is most likely the most valuable Air Test of All, It sounds like to me that you are Very well Tuned in to what your machine is saying because YOU have recognized the sound that we are discussing in the first place So well done for taking that on board because 85% of people don't maybe more,

Anyway practice (Air Test) those sounds and keep those signals at the forefront of your mind because there is a nugget close by with your name on It, Ok.

Good luck,, John

 

[bcfromfl]

Hi again, John — thanks so much for taking the time to explain in more detail what I need to listen for! I really appreciate your helpfulness!

Holy cow, that MXT getting to nearly two feet makes it one heckuva machine!! Like a PI!! My Gold Bug Pro has a Voltage Controlled Oscillator, but I think dedicated tones like you described are maybe better. Less room for misinterpreting signals perhaps when they are either low or high, instead of sliding up and down across frequencies as with a VCO.

I did some more practicing this afternoon, and testing. First, I put the penny back into the hole at 12”, and got these results:

- At depth, with no dirt on top: no signal
- Filled dirt back in, packed with my heel: no signal
- Sprinkled dirt with a gallon of water: no signal
- Returned after two hours: no signal

This seems to reinforce the idea that, previously, something happened to the ground over a period of time.

Then, I got out my lead samples, although the best I was able to do is determine that they all gave variations of positive signals at the limit, however faint. Even though I could see the samples on the ground in front of me, I pretended that I was swinging the coil as “ignorantly” as possible. The .03 gram sample seems to be about as small as I can be assured of hearing, if I’m lucky enough to be right on top of it. I might get a half-inch on something that small. Otherwise, the .9 gram sample was detected at approximately 8”. I know there are nuggets much larger than that where I’m going, but there are also many, many, sub-grammers too, scattered around on bedrock.

I’ll have to ship the detector with the rest of my gear soon. I think I’ve done about all I can do beforehand, without having actual nuggets to practice with.

Thanks again for your help!