Did I give someone the wrong advice????

[Lamar]

Dear group;

I have a honest question for all of the fine members of this forum. A couple of days ago I offered some sincere advice pretaining to the depths and the performance specs of PI detectors vs. VLF detectors as they pretain to nugget hunting and someone wrote a very nasty reply in regards to my post. I am wondering if I perhaps gave the original poster some bad advice or not. All opinions on this matter would be greatly appreciated. Thank you!

Your friend;

LAMAR

My advice to the original poster

Dear group;

I noticed that the test which was posted on this topic did not include any Minelab Pulse Induction (PI) detectors. I happen to own two different Minelab PI detectors, the GP3000 and the SD2100v2 and I can pretty much guarantee that if someone were to bury a kilo of coins at 2 feet depth and gave me a crack at finding them, I'd slap on an a 24X12" Coiltek UFO mono or a 25" Nugget Finder mono coil and I'd walk away with a kilo of coins, especially if the test was conducted in ground with very mild mineralization.

This is pretty much a no-brainer when it comes to the Minelab PIs. They are so much better at pure depth than the VLF detectors that it's not even fair to attempt to compare the two types of detectors. The biggest single limiting depth factor to the Minelab PI detector is not the detector, nor the ground mineralization, it's the size and shape of the coil that's has the biggest determining factor concerning depth.

Ground mineralization can play a decisive role in a detectors' ability to detect nuggets at great depths, even the PI detectors. The problem is that looking for gold nuggets requires the detectorist to venture into areas with high to extremely high mineralization in order to stand a good chance at uncovering gold nuggets. The old saying that "Iron is the mother of gold" is very true and a detectorist stands his best chance of locating nuggets in areas with the highest ground mineralization. Salt is also a big factor in determining a detectors' depth and gold likes to form in zones where there is a high salt content in the surrounding matrix.

High concentrations of halides (salt) affect a Minelab PI detectors' depth much more than ferrous mineralization does. Even buried, damp charcoal from an old campfire can be detected with the Minelab PI detector, this is how sensitive it is to changes in ground mineralization. You can pretty much disregard using a VLF detector to search for gold nuggets, as the areas in which they can be used are limited to areas with very mild mineralization and as such, these zones are much more rare than highly mineralized gold bearing zones.

Before you conside me to be biased towards PI detectors, I also own a VLF detector and it's a White's GMT-E series and it does one thing VERY well. It finds ground mineralization better than any other detector I've ever used. When detecting a brand new area, I like to start out with the GMT and locate all of the highly mineralized patches of ground. Once they've been located I put the GMT away and go to work with my SD2100v2, or in rare cases, with my GP3000. It's been a very good system for me.

To answer your original question, 3 feet of pure depth is pushing the extreme outermost fringes of even a PI detectors' depth range and I seriously doubt that there is a PI detector built which can penetrate the ground matrix much more than 2 feet. I've personally dug up old tin cans at 20 inches and they sounded sooooooo good from the surface! OK, I didn't actually gig them up myself, as I live in Bolivia, the poorest country in South America and in order to do my part to help the local economy, I always hire a young man or two for a few dollars a day to take charge of all of the excavation portions of my nugget hunting ventures, which then leaves me free to pursue other more important activities, such as pondering what will be the patch to detect in. I also place these youngsters in charge of all of the heavy transportation requirements. All in all, it's a pretty system, my friend.

Your friend;

LAMAR

The response to my post from another member

Sometimes, I just can't hold it in..WHAT A PILE OF BS!!! This Lamar guy is either a shill, or doesn't know squat about operating a VLF detector. I've found thousands of $'s of gold in extremely mineralized areas (I can even pull up the official gov. geo-surveys) and, while a VLF won't get the pure depth of a ground balancing PI, it can sure find nuggets. I even found gold, with a VLF, in an area that (due to the type of mineralization) a PI was pretty much useless. I don't know how many thousands of prospectors, hunting bad ground with VLF's, have found plenty of gold. What, before the advent of ML PI's, these guys just sat around, thumbs up butts, and moaned about not being able to detect for nuggets? I outta post a link to this guy's post on the other gold forums.. they might just get a laugh out of it. ..Willy.

[Reg]

Hi Lamar,

Actually, there are two independent tests being run where a kilo (or more in the second test) of coins is buried at 2 feet to the top of the coins and so far, no detector has detected them including a Minelab 2200 with an 18" mono coil. One test is a kilo of copper and silver coins and the second is all silver coins (silver quarters) and is more than a kilo. One test is in England and the second is back east here in the US. What I don't know is if other coils have been tried on the SD.

I also can't tell you the ground conditions. Here is the link to the test in the US which is being conducted by Carl Moreland.

http://thunting.com/geotech/forums/showthread.php?t=11831

I can hear the howls now, but I doubt the coins will be detected by a ML PI regardless of the coil used. I doubt they will be detected by any detector. However, it would be nice for someone to offer to let Carl Moreland use one of the coils you mentioned just to be sure.

As for the PI, the reason or reasons it won't detect the coins is/are of a technical nature as to why it won't happen.

As for the debate on VLF's vrs PI's, that could create a much greater debate on a neutral site rather than one basically dedicated to ML PI's.

As for VLF's doing a great job of detecting ground problems, well PI's work as well at the ground changes also. In fact, that is one of the initial reasons for the development of the PI's to begin with.

Contrary to what you said, PI's do not detect charcoal or any form of burnt wood as many people believe, but VLF's do. Unfortunately, many people have their mind made up about the PI and charcoal and there is no use discussing the facts of the issue. Now, feel free to take a full bag of charcoal and test it yourself for those of you who are curious as to whether I am correct or not. Just do not place the bag of charcoal on a can lid while testing.

Ok, this should get this post going.

Reg

[Miner Matt]

Reg, your charcoal statment is false My group detected a area this last weekend that had been burned and the burnt roots were giving us fits.Mind you it my not be the charcoal but the ground aroud it might have been changed.Try lighting your charcoal on fire and cover it up after it has burned and see what you come up with.

Lamar your statements area true and corcect for your area Im sure.

I ran a Gold bug for years and the area that I used it in was super hot ground most of the gold could only be detected at about 2 in. But one time in the same ground I detected a solid 2oz.chunk of gold at 18in.with the goldbugs 14in elip.coil.That was the deepest thing I ever dug with the goldbug.

If I would of had a PI this would of been no big deal.

The deepest thing I ever dug with a minelab(3500) was a backhoe bucket tooth at 33 inches. Both of these targets were measured.

Take care,Matt

[~LARGO~]

Hi all,

Contrary to what you said, PI's do not detect charcoal or any form of burnt wood as many people believe, but VLF's do. Unfortunately, many people have their mind made up about the PI and charcoal and there is no use discussing the facts of the issue.

Not intending to cause a big stir, but simply to comment about PI's detecting burnt charcoal or other burnt remnants, I would offer that after a huge rangefire, (not to be confused with the remains of a dead campfire) the fire consumed roots of sagebrush can and DO give the PI operator a very deceptive and hence irritatingly similar sound of a metal target. This being the case, it would be the foolish operator that would not investigate such a signal.

I know from personal experience as well as other peoples comments regarding this phenomenon, that these undisturbed consumed remnants of the sagebrush roots, which can be burned for a great distance underground, have fooled many a PI operator.

I have no idea however, how a PI might respond to a bag of charcoal, there could be a difference, as charcoal, I believe, is what it name implies...<char>..unburned, but burned/charred/ but ultimately burnable wood. Whereas, the powdery substance left of a sagebrush, being unburnable, as there is nothing left to burn, could be the difference between a detectable (burned, completely consumed) and non-detectable substance, (in this discussion, being charcoal).

Probably its all in the semantics, BUT

I just thought I would toss this tidbit in...

~LARGO~

[Lamar]

Dear Req;

I must also respectfully disagree with the statement that a PI detector will not detect charcoal. My GP3K will will detect an old camp fire very well, especially after a nice rain has soaked the ground. It will only do this with the larger DD coils however, such as the Wallaby and I've yet to experience this phenonemom with mono coils for some really weird reason. My GP3K will also detect broken pottery and even old broken glass pieces! On the other hand, my White's GMT-E will detect tree roots and worms, of all things!

Your friend;

LAMAR

[rexb]

Ah, my GP3000 does detect burnt roots. The effect lessens a little when you dig out part of the roots on the surface. So, at least for this model Minelab PI it is a no-brainer, tried and true fact.

[Reg]

Sorry Rexb and Lamar,

Your PI's are not detecting the charcoal and no, it is not a tried and true fact. What you are detecting is the alteration of the ground mineralization caused by the fire. Simply try the bag of charcoal test.

Largo,

Charcoal is simply charred wood that has been heated in the absence of oxygen. This allows the wood to carbonize which is why it becomes detectable with a VLF.

If you don't like trying to detect charcoal, then simply burn a 2 by 4 and then try to detect it. (take the nails out first and then move it from where it was burnt). You can do the same using a tree limb or any other wood. The results will be the same.

Don't be afraid of trying the test.

Reg

[Lamar]

Dear Req;

That makes sense, because after I dig up the charcoal, I can disturb it with my foot or my shovel and the signal disappears. I tried the charcoal by itself just a few minutes ago and YEP! You're right, it won't detect the charcoal lying on the unburnt ground. But why does my GP3K pick up old pottery pieces and some types of glass, especially blue colored glass? My GP3K LOVES that blue colored stuff!

Your friend;

LAMAR

[JW.]

I think the response is a little overboard, you didn't say the PI's were better. He is carrying over another argument, it appears you were trying to answer a specific depth question and he took that for a blanket statement about VLF machines...

The PI vs. VLF debate is as bloody and heated as the DFX vs. Explorer debate, but that pales in comparison to the white vs. orange coil debate... Sometimes you get sniped for no reason and from left field...

His points are true but so are yours, so what can you do...?

Why is Carl testing silver with a gold machine?!?!?! I think he is trying to develop a coin based PI...

Would the signal be more responsive if it were a kilo of gold? I gave up trying to use my GPX for coin shooting in parks...

Reg, great stuff, never heard it explained, so would the same hold true for graphite schist, the extreme change in ground matrix produces a signal...? Or is it a different condition.

I'm always amazed at how small a piece of metal the PI will detect which is great but not painfully small as to make it difficult to recover from the dirt, also the salt thing would drive me nuts with a VLF... My VLF is for coins and it would never find a small piece of gold, but i'm also not fighting the ground balance all the time either...

HH

JW

[Reg]

Hi Lamar,

Your ML or any PI for that matter will or can detect some pottery because of the mineralization (ferrous oxide) in the pottery itself. It is the intense heat used to make the pottery that causes the transition of this ferrous oxide from not being able to detect it to becoming something that is easy to detect. The general consensus is the ferrous oxide whether it be magnetite or hematite or some other oxide evolves to a form of maghemite that is detectable.

Fires or other intense heat sources can cause this change. Eric Foster has discussed this several times and has discussed how PI's are/were used for hunting artifiacts by searching for anomalies in the soil signal, indicating a possible hearth.

In areas that have burnt, it is very easy to assume the charcoal or burnt wood is what is causing the signal change, when in fact, it is the mineralization in the ground that has changed because of the intense heat caused by the fire and it is the change in the mineralization that is now detectable.

BTW, thanks for testing. Most people will not do that.

Now, I need to go back to another thread and modify it. In that thread I mentioned the Henry Ford was given credit for developing charcoal, but meant to say he was give credit for making the first charcoal briquette.

Reg

[Lamar]

Dear Req;

Wow, this is super cool! I went to the site of a recent fire (about 1 month old) and YEP, the detector could detect the changes, slightly but very noticeable. To test further, I then wet the burnt ground thoroughly with water and the signal strength increased just a bit. I am getting smarter every day! Thanks Req!!!

Your friend;

LAMAR

[Reg]

Hi JW,

You mentioned you could find the coin cache 2 feet deep with your ML, remember? That is why the discussion and the mention of the SD.

There has been an ongoing discussion about depth and what to expect on several different sites. I do recommend all people read what was linked and now this link.

http://www.garysdetecting.co.uk/hoard_test.htm

Hopefully, this will answer some of the questions you asked including why Carl used a bunch of silver coins.

Now, what Carl was simply trying to do is to duplicate the testing to verify what is being said on the other website and that is to determine whether a hoard of coins could be detected at a depth of over two feet in depth.

No, he is not trying to design a PI to hunt silver. He is just trying to verify what others have been saying about what can be found at what depths.

Now as to your question about a kilo of gold and whether it could be detected at the depth mentioned, that would depend upon gold itself. If it were a bunch of coins, I am not sure it would be detected. If it were a solid lump, then the odds are much greater.

Now, I don't know much about the graphite schist. I have read some discussions about it but I have never tried testing a piece. A large enough piece of graphite is probably detectable even with a PI if it is pure, solid and thick enough. The key is its conductivity among other things.

The signal from the coil has to be able to create a signal in the object and that created signal has to be able to last for a finite period of time.

Now, on metal objects such as gold, silver and copper, the ability to detect them is not only a function of the pulse but the length of the pulse. A longer pulse signal is needed to find higher conductive objects such as silver and copper if one is trying to optimize depth capabilities of the detector. Gold not as good of a conductor as silver and copper so it can be detected well with a shorter pulse.

To find extremely small gold, then a short pulse works best because it will allow one to sample sooner. So, there is no single perfect PI out there. The signal from small gold comes and goes extremely fast. Unfortunately, this same setup doesn't work so hot for large gold and some depth is lost on it. The bigger the gold (providing it is solid), the longer the pulse that is required to obtain the maximum depth capability.

I have made several mentions about what I call "invisible nuggets" in different threads. Now, when people first look at these nuggets, they appear to be large enough that any PI should easily detect them. People are really surprised when they can't get even a whimper from them. The reason for the inability to detect these nuggets is the fact the signal comes and goes so quickly. So, when the typical PI takes its sample to look for a target, the signal from the small gold is already gone. Thus, nothing is heard.

Now, what confuses things is extremely small iron doesn't respond the same as small gold. The tiniest of iron or ferrous junk can create a strong signal that is easily detected, thus giving the impression that similar size gold will be detected also. Unfortunately, that isn't true. The signal from gold is a very mellow signal when compared to that coming from a piece of ferrous junk. The gold signal is also much shorter in duration which also makes it more difficult.

Reg

[JW.]

Hi JW,

You mentioned you could find the coin cache 2 feet deep with your ML, remember?

I did? I hope my GPX could but I have never tried, I was just wondering why silver, I read the links and can't find a post by me anywhere... It wouldn't be the first time I don't remember posting something, but I am going to try the test with my PI and my Explorer, any coil I want right?... ;D

I was also replying to Lamars's question...

Would lead be a similar response when given a similar weight and size of a gold nugget? Please say yes...

I have mucho respect for Carl and wasn't trying to down talk him at all, I just know he has a project in the works and was wondering if this was it... I heard of the gold test for the dowsing rods and the prize and rules for that, this test is new... So it is coming up no target response...

Not what I would have expected...

HH

JW

[Reg]

Hi JW,

You are right, you didn't mention the cache and say it could be detected with your ML. Sorry about the mistake. I simply read too many posts at once and got the people mixed up. That comes with old age and trying to do too many things at once.

Now, as for lead and how it reacts when compared to gold when using a similar size or weight, I would hate to say for sure that it will be exactly the same. I think it would be close enough for many purposes but not as close as some other metals.

Again, Eric Foster comes to mind and he has mentioned that Aluminum blocks work well as a substitute for large gold. Since they (meaning aluminum blocks) are not as easy to obtain, I would personally use lead if nothing else was available. I don't know just how much of an error would be introduced but I wouldn't worry about it. The reason is simple, it is extremely difficult to get two similar size or weighted gold nuggets to read exactly the same, especially if they come from different places. So, there isn't a consistent reference point to begin with.

Some time back Eric Foster mentioned some testing he did with gold where he alloyed gold with silver and tested it to see how well it could be detected. Pure gold was the easiest to detect and all went down hill from there until there was a 50/50 mix of gold and silver, if I remember correctly. Then the depth capabilities rose again.

Now, remember, different alloys can cause different capabilities of detection, but so can shape and texture. A coarse rough nugget will not be detected as well as a solid mass.

So, there is no easy way to determine just what will happen in the field. As such, all a person can do is get an idea using something like lead and hope for the best.

Reg

[Uncle Ron]

It's simply too late tonight for me to read the details of these posts, but, if someone else hasn't already pointed it out, fire "oxidizes"....The ferrous mineral content of the ground then becomes oxidized and forms a halo that is detectable...Extremely so....Like a big ol' crust of rust...That's why the detectors pick up the signal...Cheers, Unc

[~LARGO~]

Hmmm,

Not to belabor a point, but I will anyway, it has been said, that remnant of burned sagebrush, (the powdery substance, not the charred roots,) is not detectable, what we are hearing, then, is simply the detector sensing the altered mineralization of the soil caused by the intense heat of the burning sagebrush.

I guess I can reluctantly buy into that somewhat.

Then would it not be true that the millions of locations of ground hits by lightning, would surely be detectable as well?? I do know that sand can be fused into a solid tube like structure (fulgerite) by lightning, and that might be a good way to find them!

Jest curious...like a cat...

Thanks!

~LARGO~