A Mono Coiled Minelab GPX 5000 vs Garrett ATX with its DD - Part 4

[Bearkat]

A Mono Coiled Minelab GPX 5000 vs Garrett ATX with it's DD - Part 4

The goal here again is to see which detector most likely might walk right over gold with 4 buried gold nuggets...check out the results:

 

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[GarretDiggingAz]

Bear
Thanks for the two vids. You didn't answer if you could GB out the hot rock. I think Steve answered it though I think in his article.
I'd like to find out the depth of some of the smaller nuggets in the undisturbed ground. I know those small pieces Steve found were small, but I don't recall a depth.
I mean, would it be reasonable to think that either machine could get a .2g at 6"-12"? It seems that at most most machines are lucky to find them at 2-4".

 

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[goldchaser3]

To those people interested in the big coil - check out NQExplorers on Youtube - they are in Australia and have posted some tests with large targets and depth. Also in some highly mineralized ground, I believe.

 

[Bearkat]

GarretdiggingAz - Sorry dude I missed that part. Yes; I could ground balance out the hot rock and keep going...It will still pick up small gold if doing that.
I don't know of any detector that will pick up a .2 gram nugget at 12"...when you find it, please let me know! I'd say the ATX max on that size would be 4"...maybe more if it was flatter...but maybe only an inch...but that is still stretching it. GPX 5000 pretty much the same...

Bearkat

 

[Jim Hemmingway]

Jim, so what your saying is the GPX can locate a nugget in tightly packed ground over loosely pack ground?

Hi AZ… geez I hadn’t thought of it that way, so no that is not the point I was making above. I don’t know if that is true or not… it’s not something I think about… maybe Reg could supply a technical answer if he happens to see this.

What I was thinking is that when a hole is dug and a test target is buried the soil has been disturbed. Digging and refilling a hole creates a localized soil anomaly. Perhaps it results from the disruption of the soil’s electrical continuity, the soil’s magnetic fraction, or whatever other factors may be involved… your guess is as good as mine.

But in my experience with my units here AZ, a freshly buried test target will not respond with the same signal strength as can be expected from an identical target that has naturally settled or occurs in undisturbed ground at the same depth. Nor will such test targets target ID on a VLF nearly as well as can be had with undisturbed targets at the same depth in the park down the road. Same soil type… but undisturbed ground.

I have read that some European detectors are very good in disturbed ground with respect to depth AND target ID. It leads me to speculate that at least in part it depends on how signals are processed… but beyond that I can’t comment.

This past autumn in silver country, I experienced a far more extreme example. I got a decent high-low signal with my Infinium and dug. I can’t say how deep the small ore sample actually was… anywhere between one and six inches. I dug a decent little hole but no sign of a target… normally I can spot them. Rechecking the hole produced no signal. Checking my dirt pile produced no signal. I then swept the dirt pile with my Propointer and got a signal from a coin-size silver ‘stringer’ type ore. And that was the source of the signal because there was no signal remaining in the hole.

Some might speculate it was a so-called halo effect that allowed that piece to signal, and once the halo was removed, no signal. I don’t subscribe to that theory because… except for rusting ferrous targets… I don’t believe the residues leached from non-ferrous targets are sufficient to support signal producing eddy currents to a sensitive VLF let alone a PI unit. There are other theories that attempt to explain such occurrences, but I don’t know that any are accepted as fully adequate explanations.

I prefer to assign responsibility for such oddities to “disturbed ground effect” whatever the heck that fully comprises… and get on with detecting. In this example however, that silver ore would also not give an air test signal when swept very closely across the Infinium’s 8” round mono coil.

Jim.

 

[GarretDiggingAz]

Hi AZ... geez I hadn’t thought of it that way, so no that is not the point I was making above. I don’t know if that is true or not... it’s not something I think about... maybe Reg could supply a technical answer if he happens to see this. What I was thinking is that when a hole is dug and a test target is buried the soil has been disturbed. Digging and refilling a hole creates a localized soil anomaly. Perhaps it results from the disruption of the soil’s electrical continuity, the soil’s magnetic fraction, or whatever other factors may be involved... your guess is as good as mine. But in my experience with my units here AZ, a freshly buried test target will not respond with the same signal strength as can be expected from an identical target that has naturally settled or occurs in undisturbed ground at the same depth. Nor will such test targets target ID on a VLF nearly as well as can be had with undisturbed targets at the same depth in the park down the road. Same soil type... but undisturbed ground. I have read that some European detectors are very good in disturbed ground with respect to depth AND target ID. It leads me to speculate that at least in part it depends on how signals are processed... but beyond that I can’t comment. This past autumn in silver country, I experienced a far more extreme example. I got a decent high-low signal with my Infinium and dug. I can’t say how deep the small ore sample actually was... anywhere between one and six inches. I dug a decent little hole but no sign of a target... normally I can spot them. Rechecking the hole produced no signal. Checking my dirt pile produced no signal. I then swept the dirt pile with my Propointer and got a signal from a coin-size silver ‘stringer’ type ore. And that was the source of the signal because there was no signal remaining in the hole. Some might speculate it was a so-called halo effect that allowed that piece to signal, and once the halo was removed, no signal. I don’t subscribe to that theory because... except for rusting ferrous targets... I don’t believe the residues leached from non-ferrous targets are sufficient to support signal producing eddy currents to a sensitive VLF let alone a PI unit. There are other theories that attempt to explain such occurrences, but I don’t know that any are accepted as fully adequate explanations. I prefer to assign responsibility for such oddities to “disturbed ground effect” whatever the heck that fully comprises... and get on with detecting. In this example however, that silver ore would also not give an air test signal when swept very closely across the Infinium’s 8” round mono coil. Jim.

Jim
That's an odd one for sure. No signal after digging that silver. Even doing an air test on it. Yet the pointer picked it up. Could it be the content of silver wasn't as high and was mixed with lead/tin and it was GB out. (Not sure if infinium does that, since I've never used it). Possibility?

 

[AzViper]

Hi AZ… geez I hadn’t thought of it that way, so no that is not the point I was making above. I don’t know if that is true or not… it’s not something I think about… maybe Reg could supply a technical answer if he happens to see this.

Jim.

I am totally out in left field when it comes to metal detectors. Just thought I would throw that out and see the replies. From reading everything I can about the Garrett ATX and the price of which (nearly 2/3's less than GPX 5000 after all the extras) it falls in a prices range that reachable for many. Even has me think of stepping up to a PI for those times I may not be able to dig in the dirt. Hell those times may already be near as I have no clue how I will respond to having a shoulder joint replacement next week. Garrett has raised has the bar in the PI's priced in the $1200.00 to $1700.00 range that the next hurdle that being the ATX will have many joining the ATX crowd. Will be interesting 2014 to see how other MD designers respond.

 

[Bearkat]

Jim - "But in my experience with my units here AZ, a freshly buried test target will not respond with the same signal strength as can be expected from an identical target that has naturally settled or occurs in undisturbed ground at the same depth. Nor will such test targets target ID on a VLF nearly as well as can be had with undisturbed targets at the same depth in the park down the road. Same soil type… but undisturbed ground."

I have got some signals with the ATX that were pretty strong out in the field, Like those tiny little boot tacks that are found at old mines, etc...
The signal was fairly strong on these depending on depth...when finally recovered and waved over the coil, the signal was slightly degraded. Definatley targets that are in the ground a while produce crsiper louder signals than same targets freshly buried.

I did one hunt couple weeks ago with the ATX, that I called it the tiny target hunt as all I got were tiny peices of metal from lead, rusty tin, boot tacks to just random small stuff. All were .2 gram and less. Some were wispers. Maybe I'll get a pic of all those things and put it here. Its just all junk but shows the ATX getting tiny things.

Bearkat

 

[Jim Hemmingway]

Jim
That's an odd one for sure. No signal after digging that silver. Even doing an air test on it. Yet the pointer picked it up. Could it be the content of silver wasn't as high and was mixed with lead/tin and it was GB out. (Not sure if infinium does that, since I've never used it). Possibility?

Yes it is an odd occurrence GarretdiggingAz but I've had similar experiences over the years. My exposure to such occurrences is undoubtedly much greater than for the goldhunters because I come into contact with quantities of all sizes and varieties of silver or silver related ores probably on the order of 50:1 or even a 100:1 ratio or even more by comparison... silver is plentiful. In any event that ore piece wasn't anywhere close to the Infinium's GB point (zinc penny) over that ground... that piece target IDs as low foil... typical stringer silver ore.

Now I don't want to complicate this reply, but for background info... ore conductivity by itself does not produce a direct relationship to PI unit ground balance scale positioning. An ore's GB point is governed to a large extent by its conductivity, but other factors play a role such as size, shape, structure / character, purity, type of mineral inclusions, and so forth. For example I can produce any number of ores that have almost identical target ID readouts but whose GB positions vary considerably on the TDI Pro's GB scale. That's a fact... ores are not man-made coins whose physical / chemistry characteristics are replicated to very precise tolerances such that their GB points are predictable.

If you want to read more on this topic go way down to the Canada forum where I tend to store my articles, and you'll see a thread entitled the TDI Pro in the Silverfields. It's a boring read really, but you'll get the idea by examining the charts. Or just look at the photos below... the 10.1 lb specimen has a GB position that lies between the high (HSEP) and low conductive signal endpoint (LSEP), roughly about GB5... as compared to the 2.7 lb piece with a GB at 7... same VLF target ID, but different ground balance points.

Jim.

​

 

[GarretDiggingAz]

So a question I've got then is, How accurate is the target ID?
It seems I dig based in tone for the most part anyways. Even that's not 100%. I'll get high tone, ID of 90+, and it could be a big piece of iron or steel. So I know the ID is there to give something. A false security on target? Prior to that it was only tones, and I think it pretty much still is. Of course that's a totally different topic.

Jim
Does silver always give a high tone?
I could definitely see how you get more experience on that especially since silvers more abundant than gold. I had actually thought of buying a silver claim, but unfortunately not in this state and I know wife wouldn't move. I wouldn't want it as a vacation property. So I'd have to hire a crew to mine when not there. Just not going to happen.

 

[Jim Hemmingway]

So a question I've got then is, How accurate is the target ID?
It seems I dig based in tone for the most part anyways. Even that's not 100%. I'll get high tone, ID of 90+, and it could be a big piece of iron or steel. So I know the ID is there to give something. A false security on target? Prior to that it was only tones, and I think it pretty much still is. Of course that's a totally different topic.

Jim
Does silver always give a high tone?

GarretDiggingAz… no I’m afraid not, in fact most naturally occurring silver in my area is considered to be low conductive. Silver nuggets and ores here have a target ID range from foil to silver dime, but no higher.

A silver sample’s benchtest conductive readout results from its physical / chemical make-up. Silver purity, types of mineral inclusions, structure, size, and shape are the primary factors that impact target ID.

For buried targets, ground conditions exert quite an influence too. Moisture content, iron mineral magnetic susceptibility, disturbed ground conditions for example urban renewal projects, and the target's profile presented to the coil…all further impact target ID. These factors can result in good silver reading down into the iron range despite a specimen's physical / chemical make-up.

So in a prospecting context, don’t trust target ID unless you are right on top of a good strong signal. I can’t tell you how many times in the past I’d get an interesting readout in the more elevated conductive ranges only to watch such readouts evaporate away as I got closer to a rusty bent nail.

Jim.