test nuggets

[robbor]

I dont have any test nuggets, is it easy to melt fine gold down into a nugget say with a mapp gas torch?
Or can it be used as is in a small vial on string?

 

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[Hoser John]

Detectors read the tiny pieces as one-go for a good 1/2-1 gram nugget-trade fines for a small nugget and glue to a red poker chip for ease of retrieval-tons a au 2 u2 -John

 

[chucktx8]

I have used this one for years,

 

[bugs]

Go to eBay and you can buy any size test nugget you desire. Then apoxie it to a clay or plastic poker chip.

 

[AUDuke]

gold melts at approx 1950 degrees F. I doubt if Mapp gas will do it. A US nickle is about the same conductivity as gold, just cut a small piece off of a nickle. Just as good and a lot cheaper.

 

[Hoser John]

close to counts in horseshoes and handgrenades only--look at a notch machines notch capabilities and the proof is self evident-rings(mixed gold)semi work too BUT pure american gold is usually much purer than fabricated gold. There are places in Georgia and Kalif that their respective states geo dept has analyized at some up to 99%--mother natures real oro puro--tons a au 2 u2 -John

 

[AUDuke]

No two nuggets are exactly the same in their conductivity. Gold from one area is different from gold in another and a nickle falls in the same range. I defy anyone to tell the difference between a piece of a nickle and a piece of gold of the same size. and shape with a detector, I have been detecting since the 1960's and nugget hunting since 1982, and I can't do it. I have found gold nuggets from 60 percent to around 93 percent in this country, never 99. Generally, the finer the gold the purer it is.

 

[Hoser John]

Every states geo dept has the reports and analysis of compositions-READ AND EDUCATE--John

 

[AUDuke]

Results speak for themselves

 

[Dallas]

I use Clear Fingernail Polish to attach my nuggets to plastic Poker Chips. I like the White Chips best.

 

[patches63]

ahh, why bother. open yer tackle box,grab some small split shot,rip some in half.hammer half each size flat.if only large weights,put on wood block,chop to size.plan b go to tackle shop.cheaper than gold sounds the same.lead and gold conductivity nearly the same.run a minelab 4500 regurlarly and gave a friend my test nug other day 1gram. guess what im usin? (wheres dat takle box?)

 

[Shortstack]

Why not just go to a local jeweler who does repair work, and buy a snippet of 18 or 24 ct gold.

Or, buy your sweetie an 18 or 24 ct. yellow gold necklace and have the jeweler remove one or two links for your test target. Simple. You get loads of "sugar" and your test samples. Remember Christmas is only 3 weeks away.

 

[inthedark]

I dont have any test nuggets, is it easy to melt fine gold down into a nugget say with a mapp gas torch?
Or can it be used as is in a small vial on string?

There are alot of paydirt dealers on the web. They usually salt the bags with a few small nuggets.

Not overly expensive and you can get some panning practice also.

google 'buy gold paydirt' and you will find them

Frank

 

[Reg]

Hi Robbor,

Auduke is correct, no two nuggets are the same. What makes nugget hunting even more complicated are the conductivity extremes that can occur. These extremes will not have nearly the effect on a VLF but will certainly make a big difference on a PI.

As an example, I have a 1 grain nugget I can detect easily with my PI but I also have an 8 grain nugget that is extremely difficult to detect with most PI's. A good VLF designed for nugget hunting will detect them both.

A lot of people are not that familiar with the fact that gold or the detection of gold can vary to such extremes. The character of the gold can influence how a nugget is detected as can the purity. A coarse rough nugget may be much harder to detect than a nice solid one. Crystalline gold could be even worse.

Silver is a great conductor but mix it with gold and a gold nugget becomes quite different in how it reacts on a detector because of the change in the conductivity. The change can be so dramatic it isn't funny, especially when using a PI.

Here is a link to a chart that displays the conductivity of gold as it is alloyed with other metals. Now, the chart may not mean much without knowing the conductivity of other metals, but as an example, add a little silver to gold and the gold goes from a high conductor (pure gold) to a low conductor that is quite similar to lead in how it is detected.

On a PI such as the Whites TDI, the tone of a target can change with the conductivity of the metal, meaning low conductive targets can generally be distinguished from high conductivity ones. This works great for separating silver and copper coins from other objects, but not so great when nugget hunting. As an example, a 1/4 oz or larger near pure gold nugget may cause a nice low tone, but a less pure 1/2 oz nugget from another location may cause a high tone. When using the TDI, it helps to know more about the gold and how it will respond in the area you are hunting.

Again, this conductivity thing isn't as critical when using a VLF but the conductivity aspect still makes a difference. This difference may become a little more noticeable between detectors also, because of the frequency difference of the detectors.

So, what is this long winded post trying to say? Well, one can use a small nugget for a test piece but they can use a piece of lead about the same size also and still be in the ballpark as for having a test target that mimics gold. It all depends upon the gold characteristics. So, Auduke's suggestion of using a piece of a nickel works as well as anything for those who don't have any small gold to make a test target.

Reg

 

[Reg]

Hi Jim,

Sorry for no link. I will try again.

http://www.deringerney.com/materials/GoldandGoldAlloys.asp

Here is a link to general conductivity of metals so one can sort of compare. Keep in mind that the numbers will not be exact between the two charts because of specific measurement standards used, but the general range can be seen.

http://www.kp44.org/ftp/ElectricalConductivityOfMaterials.php

If you look at the two charts, you will see pure gold is 77 on one chart but 70 on the other. Now, both charts do use copper as the standard of %100 or the number 100. In either case, the numbers 77 and 70 are quite close when compared to other metals and their numbers.

A high silver content in gold generates a 10 on one chart. Now, pure lead is about 7 on the other chart but could easily be a 10 with a few impurities. So, this sort of shows why gold can be all over the place and be detected more like other metals than pure gold.

BTW, the chart of all metals shows that aluminum is fairly close to near pure gold in terms of conductivity so that is one reason it is recommended to represent gold in some of the OZ tests.

Reg

 

[Jim Hemmingway]

Thanks Reg, the alloy chart is particularly interesting to me.

I've always suspected that mineralized inclusions (for example...both conductive and non-conductive iron, cobalt sulfides, nickeline, arsenic pyrite) play an important role in drastically reducing conductivity with my silver finds.

I've been wondering how one can assign a relative value to this variable factor in relation to other parameters that also directly affect the overall conductivity of silver (gold) samples in the ground. For example, size, shape, structure or "character" if you will, not to mention the effects of various mineralizations present in the soil affecting (phase shift) conductivity, regardless of whether they're marginally or more (various salts) conductive, non-conductive iron (especially magnetite and maghemite, and to a lesser extent other lesser magnetic susceptible iron oxides) or other sulfide minerals that are variably present in soils where I frequently search. Quite a mish-mash potential there. Doubtless it can be expressed mathematically, but equally doubtless it would have no practically useful value to electronic prospectors.

From a slightly different angle, I've found small 22K rings that read in the screwcap range, whereas somewhat similar size/shape 18K rings read well down in the upper foil range.

Last night I went through my finds over the past several decades, and found an exact shape/design match between one of those 22K rings and a very slightly smaller .925 silver ring. On F75, the 22K read "54" while .925 silver read "85". I think despite this being a single sample result, it does nonetheless exemplify a part of the message you've conveyed here. Thanks...its all fascinating stuff,

Jim.

 

[Reg]

Hi Jim,

This TID thing works great for US coins because they are all the same basic shape and composition, but trying to use this feature for natural items found in the field and things don't go that well. The technique used on TID is to take the tangent of the signal which basically is a math function of two signals. If everything remains a constant, then the signal will remain a constant. George Payne discussed the math involved in one of his posts several years ago. He even explained why deeper targets will generally read higher than normal. Here is a link to his post.

http://jb-ms.com/Baron/IDmeters.html

Now, what all this means is just part of the equation. What isn't mentioned is the fact that the metal itself can vary some because of size, shape, hardness, purity, and even the alignment in the ground. Then there is the ground itself that can influence the final result.

Many years ago, George Payne designed a detector called the Mark 1, which had a TID function so precise one could actually distinguish some pennies from others. No, I am not referring to the difference between zincs, copper or Indian heads, but the detector could actually display a repeatable difference between certain pennies maybe a couple years apart. Considering the chemistry was supposed to be the same, the logical reason for the slight difference was thought to be caused by the stamping process, since the hardness can alter the results also. The actual reason for the slight different difference was never really determined, so I never really did know the real reason why.

Now, given all the info mentioned, all I can say is trying to use the TID feature when looking for native metals is sort of like trying to determining the length of a rope when nothing else is known about the rope. About the only thing one can do is guess and hope one is in the ball park.

Personally, I have found the TID feature to hurt as much as it might help since the variables can cause such a dramatic change that trying to interpret or guess a target based upon the TID just may cause one to eliminate good signals. I know, I have been there and done that.

A perfect example is testing a small piece of gold. If tested openly, it will normally read in the foil range, but place it on the ground and the ground influence just might cause it to read as iron. Bury that same nugget just a little and the weak signal may read clear up in the large silver, or as on the Mark 1, the dollar range. So, we can have the same nugget read as a small piece of foil, a nail, or even as deep silver with the difference being caused by other external conditions. Now, what is worse, is this same level of error can occur on most other targets given the right conditions.

Reg

 

[Jim Hemmingway]

Thankyou Reg!

The link to George Payne's essay is pretty much what I was seeking. BTW, small nuggets that air read as small foil do read in the upper iron range in my soil. Despite that, both my F-75 (JE mode disc set to 12ish, stock coil only...the 6.5 inch elliptical doesn't do as well employing small iron disc here, but does do very well in all-metal motion mode) and MXT (disc set to 2ish) with small iron discrimination dialed-in will respond clearly to say a flattish 2.5 grain nugget at a few inches (for example 3 inches max F-75 = good repeatable signal) while discriminating small iron screws up to one inch length. Now you may get an unmistakable broken signal on the larger screw in one direction, but in the other direction its gone....whereas the nugget is a clean signal in any direction.

My GB2 will not read on that nugget in iron discrimination (does cleanly discriminate the screws), but gives an excellent signal in all-metal "normal" mode, even better in the "low mineral" mode with stock coil.

Jim.

 

[Reg]

Hi Jim,

There are some not so obvious problems with using any form of motion disc mode that can cause one to miss a whole lot of targets under the right conditions. What is worse, is most people will not know it is happening.

A perfect example is a general area where I hunt occasionally has two extreme conditions, one with reasonably mild ground and few hotrocks and the other hunting tailing piles. In the area with the mild ground and almost no hotrocks, the disc feature works great. I can hunt with ease and don't have much fear of missing gold.

On the other hand, the tailing pile hunting is a different story. Many of the rocks will give signals in the all metal mode, thus making it frustrating to use. Switch to the disc mode and things do get quieter. The problem is, they get too quiet. With the high incidence of rocks that sound off, the rocks now become a means of generating negative signals which cause good targets to be ignored. The result is, many potentially good signals are simply ignored.

I realized this would happen but not at the rate I was experiencing. The reason I know it was happening was because I hunted a dedicated area with a VLF using the motion mode and then covered the same ground with a PI. The number of low conductor or non ferrous objects missed with the VLF but found with the PI was really surprising.

Many people would say, oh sure, that will happen because a PI goes so much deeper. Nope, that wasn't the reason at all. Most targets found were near surface objects which included a lot of lead bullets, brass casings, and a few other odds and ends that were non ferrous.

Next, one would say the reason for the difference was sloppy techniques. Well, I made sure I covered the area not once but twice from different directions with the VLF simply because I was getting so few target responses. Also, I didn't do anything really different when using the PI. In fact, because it was also extremely quiet except for the target responses which seemed to be everywhere. Keep in mind the rocks that were so noisy on the VLF generated no response on the PI, so the rock problem was gone.

This latest comparison was a real wake up call and a good reminder why I have both types of detectors. Hunting this type of an area works best when using a PI, but the mild ground with few hotrocks is the ideal place for the VLF because much of the gold is small.

So, there is a place for both types of detectors. At least there is in some of the locations where I hunt. Once again, I do have to say that the two types of hunting conditions I mentioned are the extreme ends of the spectrum, one being great conditions while the other is a real pain. The irony is the two areas are just a few miles apart.

Reg

 

[Jim Hemmingway]

Hi Reg,

I’m up to my ears in Christmas preparations here, but finally had enough of wrapping gifts and thought I’d do what I like best next to actually detecting…talk detectors and give you a reply.

It seems to me that times are changing. With the advent of more effective “discriminating” PIs that are more sensitive to smaller targets and affordable to metal detecting hobbyists generally, we are seeing quite an increase in the number of users. Readily available good information from folks like you, Steve, and others has served to further advance the change by pointing out the utility of these units.

We agree that VLF and PI units each have a “niche” primacy depending on the search parameters one needs to anticipate. As most readers know, these include magnetic susceptible mineral levels, hot rock proliferation, iron debris/trash abundance, and size and character of the silver/gold targets. I feel the most PI definitive parameters are the size/character of gold/silver, and magnetic mineral levels that surpass a “threshold” level whereby the sensitivity/depth capability of VLFs becomes too handicapped.

With respect to iron trash and hotrocks, VLFs can be adjusted to deal with them by and large but there is a serious catch. Sensitivity/depth on desirable targets suffers, and as you noted, masking caused by negative responses from rejected hotrocks/iron trash smothering nearby desirable target responses…may be unsatisfactory…depends on their numbers, your perspective and search strategy. Target masking can be mitigated to some extent by using smaller coils especially in concert with up-to-date (primarily Dave Johnson) units that offer improved target recovery speeds. The F-75 is such a unit that clearly demonstrates a new wave of VLF units that offer exceptional separation ability while still able to get really surprising depth even in my fairly tough ground using the tight DD footprint. While its operating frequency plays a role, other design factors further enhances its sensitivity to smaller nuggets that nips at the heels of my Goldbug2 in my reasonably high magnetic mineral soil. If one learns its nuances, it’s a very capable unit, while quite versatile otherwise.

An example perspective, if ground minerals permit effective VLF performance, and gold size at or below a few grains rules, then I wouldn’t really care too much about hot rocks. Yes, the PI will deal with them mostly, but it won’t matter if the unit won’t see the gold. As far as iron trash is concerned, sometimes its better to view finding some gold without the frustration and cover more ground…than to find some (perhaps additional) gold with the frustration of using all-metal… perhaps resulting in walking away from an area. Then too, there are folks who simply cannot afford or justify more than their current VLF, depending on time available for detecting or access to gold areas.

Your comments about locating more targets in hotrock environs that cause problems for VLF units gives rise to a question. I still have copies of your instructive comments re: TDI (the thread, sadly, is gone due to the personal comments by some first-time posters), but there is one item we never discussed. Despite being able to adjust the GB to effectively place most iron into the high conductive category while permitting the user to hunt away for the low conductors (and blocked by switching to low conductors only), do those “discriminated” iron objects serve to mask nearby desirable targets?

A few years ago I might have given you a debate over your tailings statements, but not now. Mind, your examples are polarized. I have experienced using my Infinium in the worst hot rock, pyrrhotitic (conductive) rock, iron trash infested area I’ve ever seen. Many times I was resolved to replace the 14” mono with a small DD to improve stickhandling around these nuisances, or even wander back to the truck and grab an MXT/F-75. But, I kept thinking I was about done with the area so why bother…so I persevered. Fate stepped in and kept me there for most of the trip…using the big mono.

The Infinium zero discrimination hi-lo signals effectively cover the entire range of desirable signals up to just below IH pennies. The lo-hi range right around IH pennies only… could be accurately determined on silver nuggets/ores either by sweeping the coil tip, or of course using reverse discrimination to yield a hi-lo signal. Now, the range beyond that up to and including copper penny/silver dime only, will change from a tone of lo-hi to hi-lo only in reverse discrimination. Beyond that range its all lo-hi (zero or reverse disc), but there are very few targets that fall into that range and I was satisfied to ignore the lo-hi signals in reverse disc to avoid digging much larger iron at depth, enabling me to cover much more ground more effectively.

Now, the hi-lo signal range in either zero or reverse disc does encompass considerable large and smaller iron. Some of that iron gives an interesting di-signal…a hi-lo along its width, and lo-hi along its length (magnetic and resistive properties respectively predominating…also depending on the profile presented to the coil) that many will continue to exhibit in reverse disc too. Some of those types of hi-lo (width) signals could be accurately (within the constraints of inherent nuances/conditions) distinguished from conductive ores by checking them on the coil tip. Most would change to a lo-hi signal, which revealed them as iron. In my experience there, no conductive ores will change from a hi-lo to a lo-hi signal, but some of this “di-signal” iron along the width axis will do so. More yet, I did not see one example where a piece of silver/ore will change its signal regardless of direction of coil sweep, whereas of course this iron type will do so. Another dead-give-away.

Still, I did dig considerable iron. Some that yields the hi-lo tone (zero disc) regardless of configuration presented to the coil, continues to do so in reverse disc, and that iron type along with all lo-hi (zero disc) that changes over to hi-lo in reverse disc must be dug. Mind Reg, there are other nuances such as sound level in reverse disc compared to zero disc…many larger irons suffered only a slight signal volume decrease in relative comparison to conductive ores. Most ores resulted in severely reduced reverse disc signals, and I quickly came to learn to dig those signals with enthusiasm.

And finally, I fully agree with your comments about success in dealing with tailing hotrocks while signaling over conductive pieces. The single best feature about using Infinium this year was its ability to penetrate deeply into what I will describe as “VLF spurious ground noises” and occasionally provide a discrete signal that none of my VLF units will see in small iron discrimination (I’m 99% certain as I found such pieces over productive ground I’m certain were effectively covered last year with VLF units) due to masking. Some of those “discrete” signals resulted in iron, nickeline, cobaltite, large pyrrhotite and so on…but several resulted in beautiful, large pristine native silver nuggets and high grade ores.

A further observation you may wish to comment about is that I definitely noticed the 14” DD coil got less depth, and called more larger iron as a hi-lo signal requiring digging.. How much? Maybe 15% give or take a bit. BTW, the coil tip technique worked equally well using the large DD. I did not use either the small mono or DD coils and cannot comment there.

The above aside, there were a few hi-lo signals at the units detection depth fringe that changed to a lo-hi signal once partially uncovered. One instance was a partly rusted quart-size paint can that kept me digging for an hour or so in constantly caving tailings.

The Infinium experience resulted in endless digging of deeper holes, sore (throbbing) swollen hands and forearms, plentiful… but much less large iron dug than ever before (this didn’t bother me in the least as I would have dug much of it using any VLF unit anyway). It also resulted in the most productive hunt I’ve ever had in 25 years by a wide margin. I may post a thread here about these findings early in January if I can collect some thoughts and decent photos together.

Below is a photo of moderate-sized high-grade from this trip. I don’t recollect exactly how deep it was or would have been had it not been accompanied by a very large nail maybe 10” long, and an additional small piece of ore. I can relate that my shoulder was down in the hole the day I dug this piece while my wife stood by with the pinpointer (she happened to be visiting at the time). Tough digging in a concrete-like rock matrix.

Jim.