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Mark Tillman

Searching For That Elusive First Nugget

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I'm running a GPX-4500 detector with the 8 inch Commander mono-coil. Lately, I've found that I'm getting the most stable threshold running the detector in 'deep' search mode with soil timing set to 'sharp'. Gain remains around 8 or 9 and I generally leave stabilizer set at the factory preset of 10 or sometimes drop it by a point. My question is, would I (speaking generally) be better off running my soil timing in sensitive extra when running in deep search mode? Also, since the detector defaults to a very slow sweep speed when in deep mode, exactly how slow should I be swinging my search coil, assuming a normal sweep speed of 1.5-2 ft/sec? 

 

Pretty basic questions here but I haven't had an opportunity to detect much with more experienced operators. I would describe most of the ground mineralization where I detect (the Eureka District here in western AZ) to be of average mineralization but then again, I've not detected a wide variety of locations to base this assumption on. A good deal of the metal targets I've been digging lately appear to be rather small (fragments of lead bullets, iron tacks down to 0.23 gram in weight, etc) so I have some confidence that my settings are at least not out in left field.

 

 

 

 

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First, You have a very good detector.

Second, its hard to say what might be the best setting for your area having never detected there. I would say that sensitive extra would be more generally applicable in a larger number of areas.

The fact that you are finding small bits of lead and iron show that you can find gold if it is present.

The biggest problem that new comers face is not learning the details of how to operate their detector (even though that is indeed important), the hardest thing is how to get their detector over a nugget. The beeps you hear on lead are very similar to what you would hear if your detector beeped on a nugget.

A metal detector, no matter how great, cannot find gold if no gold is present.

The Eureka district is mostly a hard rock base metal district, and not a big placer nugget producer. I would suggest you consider joining a club in the area and trying out some of the gold claims in other areas. Read some books, spend time with some of the more experienced guys in a club. Yavapai is a historic good nugget producer, but not every part of the county is productive, and the Eureka area may not be the best. best of luck, Keep on searching.

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Thanks for your comments Chris. I am interested in prospecting more areas and have managed a trip or two to areas like Gold Basin but without club connections, I get the impression that most of the best areas  are already claimed up so joining one of the local clubs in this part of the state makes sense.

 

The western edge of the Eureka District did have a few small lode type gold mines but like you said,  they may not have produced gold of sufficient size for a metal detector to detect. A couple of these old gold mines employed arrastras for grinding so I was hoping that the free milling nature of the ore also suggested a mine capable of producing at least some small nuggets but I sure haven't found anything to substantiate this notion either. Maybe wishful thinking? 

 

I've been using a small gold test nugget (about 1 dwt in weight) for setting the detector's gain-I probably should spend a bit more time running comparisons between the different 'soil timing' and 'search' modes.

 

 

 

 

 

 

 

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 Yes, do try other locations, though the Gold basin area is fine. Many lode mines with free gold produce dust sized gold - way too small for any detector. Yes there are some that produce coarse gold, but they are less common that the dust gold producers.

A one pennyweight nugget is a bit large for testing. Get a piece of lead like a small split shot fishing weight. One of the things new detector prospectors also do is to listen for loud target sounds. While near surface large nuggets exist, smaller or deeper gold is more common, and they make faint sounds. You have to listen closely to hear the gold much of the time. Most screamers are trash (though not always).

You can do it, but it takes work and skill.

Today I was out with my detector (an SDC 2300) and got 11 nuggets totaling 1.7 grams.

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It sounds like you had a pretty decent day there Chris and that SDC sounds capable of finding some pretty small nuggets in the hand of a good operator. I'm not quite ready to declare my lack of success detecting here due to my 'not swinging my search coil over any gold' (I'm not that confident yet, I'm more inclined to think that I've probably missed some of the more subtle changes in signal that would indicate a gold target below and I due tend to listen for those very faint changes in threshold) but a point certainly worth emphasizing  in that I can't expect to be successful if I don't manage to swing my search coil over a detectable nugget in the first place. Thinking about it now, I probably deluded myself into thinking that lode mines employing arrastras was synonymous with detectable nuggets and forgetting that arrastras employed mercury which would have suggested gold on a scale possibly below the limits of detection for most detectors. 

 

Thanks guys for the helpful comments and Geowizard, I'll give your suggestions for determining my 4500's detection limits a try. I'm not an electronic engineer but your comments on the time domain of a detector as a function of nugget depth sure sounds like a good explanation. I'll keep that point in mind next time I'm making my initial adjustments. 

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Geowizard,

I understand about slowing the motion speed down to improve threshold stability. Running in deep mode with the motion speed set to very slow seems to provide a very stable threshold. For where I've been currently detecting, this has turned out to be my preferred setting since other settings like sensitive extra, sharp, or sensitive smooth all seem to give too many false signals or the threshold lacks stability. I'm going to try your suggestion regarding burying small pieces of aluminum at different depths and record the various responses in a field log. I've been keeping a journal already of the locations I've detected (mainly to keep track of the various settings) so no doubt this will prove instructive.

It was my impression that the manual tune feature of the detector was primarily used to eliminate or reduce EMI by allowing you to fine tune the channel selection process after first completing an auto tune? I'm thinking that you meant to say that lower numbered channels (assuming they corresponded to lower frequency and hence longer wavelength signals) would give an improvement in search depth but I would be interested in knowing if this is not the case.

A friend recommended that I run my detector's ground balance in 'fixed' mode and just be careful to check the ground balance frequently and I've been doing that for a little while now. Seems to work well doing this.

I really would like to get out to some other areas to detect so I can get a better understanding of different soil mineralization. I was able to get up to this year's ICMJ Gold show and did some detecting during the placer training class. It was interesting to note how the soil mineralization there seemed almost benign in comparison to some of the soils over here. Watching some of the guys doing there initial adjustments and they really didn't seem too worried about ground balancing. On the other hand, it was a surprise to see how the EMI from quads operating in close proximity could really interfere with detecting in an area.

Mark Tillman

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Well I finally found my first metal detecting 'nugget' yesterday afternoon. I'm going to call it my Easter nugget although weighing only 0.25 grams, it might not qualify as a nugget by some peoples standards.  I found it in a narrow gulch not too far from my home here. When I first swept the coil (was using the 8in commander mono coil) over the target, I got a signal indicating a metal object. but it appeared that I had lost the target after digging down maybe 5-6 inches. Figuring that I had already pulled the target out of the ground, I went back over the spoils pile but no signal there either. I thought my mind might have been playing tricks on me and that maybe I had mistaken a hot rock for a metal object but before giving up I tried dropping the coil to the bottom of the hole and there it was again although not as loud as when I first heard it. I pulled maybe3 or 4 more scoops of material out of the hole before locating the small, very flattened piece of dull yellow gold and my first bit of gold found metal detecting...it had only taken me the last year and a half to do so but then no one ever said it was going to be easy!

 

The difference in signal loudness had me a bit puzzled at first, I'm guessing there might have been something of a halo effect in play here.

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Small. near surface targets that are near the limits of what the detector can see are easily lost in the dig pile. Trust me, I've done that plenty of times. When I loose a target, I check my pick as it has a magnet, if there is no obvious chunk of iron sticking to the magnet, I spread out the dig pile and look again for the target. Sometimes the target rolls or gets flung farther than the main dig pile too.

 

Congrats on the nugget, I would say that if I found it, I would call it a nugget!

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