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Hello to all, I noticed that there are a number of GMT users here so I thought I'd post here.

When you're searching for black sand deposits (the quantities of mineralisation readout), does it make a diference what coil you use? It seems that the smaller coil will give slightly different readouts over the same ground.

It is also recommended that you have to pump the coil up and down to use that feature, but this is inpractical as you'll not be covering a lot of ground. At my local goldfields today, I was struggling with this a bit, and it is an area where fine gold has been found.

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Well nobody has hit on this for you yet so I'll give you my :twocents:

I have a couple years behind the GMT and what I can tell you is I would use the stock coil that comes on it for that purpose.

#1 the smaller coil "see's" less ground therefore it should give you different readings. And I don't believe it was made for the purpose you are trying to achive.

#2 If you are trying to trace or "see" the black sand pattern in a wash the stock "DD" coil does a fine job of that, I would ground balance in the normal fashion on the side of the wash where the soil is less mineralized then proceed to swing thru the wash This will give you the readouts your'e looking for I do it all the time.

Ground balancing a GMT can be done in a couple different ways read the manual again and you will see that you can either pump it up an down or swing horizontally while holding the "GRAB" button.

Then if you like you can fine tune after that with the up/down or + - button.

Nothin 2 it

If you are really into learning more about the VLF's get a copy of Larry Salle's book "Zip Zip" You will learn even more about ground balancing and complete usage of your detector.

Hope that helped ya.

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..If you are really into learning more about the VLF's get a copy of Larry Salle's book "Zip Zip" You will learn even more about ground balancing and complete usage of your detector.

Hope that helped ya.

Great book and great advice Frank! :thumbsupanim - Terry

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Thanks for the advice, Larry's book is at the top of my list.

It is interesting that you mentioned to groundbalance next to the wash, as groundbalancing doesn't seem to affect the numbers on the right hand side of the screen (maybe it does, but I haven't found this to be the case so far), it does of course affect the reading on the left.

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Hello to all, I noticed that there are a number of GMT users here so I thought I'd post here.

When you're searching for black sand deposits (the quantities of mineralisation readout), does it make a diference what coil you use? It seems that the smaller coil will give slightly different readouts over the same ground.

It is also recommended that you have to pump the coil up and down to use that feature, but this is inpractical as you'll not be covering a lot of ground. At my local goldfields today, I was struggling with this a bit, and it is an area where fine gold has been found.

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I've been messing around with my GMT to look for decent sample areas to start dry washing. I picked up a handfull of the small wire surveyers flags. I kick my gain up pretty high, and lower my VSat as I want the machine to catch excessive mineralization vice cancelling it, and I also want max depth. Pick a straight line perpindicular to your wash and walk with the machine in front of you, without swinging it. Take a note of your readings, In the areas I've been working, the blond sands read around 12-15, and the heavier areas around 35-38, these numbers will change up or down with the level of gain. Take one or two passes over the same path from both directions to ensure consistancy, and drop a flag on the highest numbers. Move laterally 5 ft up and down the wash and repeat the process. I only wear the headphones so I can hear a hot rock or target that would give the survey an error, the machine will be very noisy. Sometimes it lays you out a nice little streak, sometimes a bunch of scattered flags. If your working a tight area, shorten your interval, and once you finish, step back 50 ft or so and circle your survey area from different angles, as the streak may run a direction you didn't expect. I've also started a log of my numbers for the areas I've found gold. Include your setting numbers with your area highs and lows data.

Good luck,

A/F

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When you're searching for black sand deposits....

Just a piece of info here-

While nearly all the detector makers somewhere in their sales literature state that a good way to find gold is to search for deposits of black sand with your detector, the truth is that doing so is an utter waste of time. Trying to find gold by seeking associated patches of black sand is a bunch of total BS in my opinion. Why? Your detector cannot tell one mineral from another and there are 1000s of reasons your detector may sound off for a mineral concentration and most of us find them even when we dont want to. Essentialy all soil in every goldfield is mineralized to one degree or another, and your detector cannot discriminate between a bit of mosture, a concentration of deep hotrocks, or iron bearing clay and black sand. You get the same resonse no matter the cause. There are many many reasons other than black sand that your detector might indicate mineral - moisture, salt, patches of tiny rusty trash, patches of iron bearing clay, etc. So if you seek mineral concentrations I guarentee you will find spots of mineralization, but essentially none of them will produce any gold. I know many dozens of successful gold prospectors and I've been pretty successful myself, but not one of them uses the mineral setting on these detectors to find gold. Its sales BS that some guy made up 40 years ago and everyone still repeats it in spite of the fact that its complete baloney. If you want to find gold, remember that gold is a metal and you should set your detector to find metals.

If you want to dry wash, do a sampling grid with your dry washer. If you hit on a paystreak, search around with your dry washer to define and work that streak. Trying to find paystreaks with the mineral setting on a VLF is no better than just throwing darts and taking a chance. If you want to use your detector to find a dry wash paystreak, set it on metal and look for a gold patch. If you find a good nubmer of nuggets concentrated in a small area, you may well be onto somthing that you could work with the dry washer. It may not work 100% of the time, but its way better than searching for randon mineralized spots.....

Chris

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Chris; I assume you are speaking of dry land searches...back in my Portola days I did use my Garrett DeepSeeker/vlf to determine the higher levels of blacksand concentrations for some of my dredger buddies...it was a good method to shorten the sampling when hunting for pay streaks in water. I don't think desert areas would have the same potential,,,as you said.

happy new year!!!

fred

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Gosh Fred... I tend to agree with you. as some old timers reading this post will remember, this was a common method back in the days of the BFO. I believe Karl Fischer

may have written articles regarding this in either/both the CMJ or Gold Prospector. Also

Karl von Mueller has mentioned this in both articles and his 7th edition book. Moreover,

I believe Wayne Winters also wrote several early articles about this..

The Garrett BFO's and early Compass TR's had mineral-metal settings. I guess it became a lost art during the 1990s along with mine dump sampling to set up a non-autotune metal detector to the ferrous null point...

For those of you who have either the White's GMT or the Teknetics T2, both have this ability (Archerfrog... I'm impressed by your post.)

However, Reno Chris is also right, about hetrorogeneous(spelling) eluvial desert deposits. the later gold machines just can't "cut the mustard"

If anyone out there has one of my early editions (1983) of Follow the Drywashers this

procedure is well explaned in Chapter three; specifically on pgs. 9-10-11.

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Reno Chris (or anyone else),

I was thinking about picking up a GMT. Cannot afford a Minelab and where I metal detect, there are only a few occassions to have a high freq machine. What is your opinion of the GMT (versus other similarly priced detectors)? I am very much a novice with AZ gold hunting. I have done some hear Leadville, CO and Blackhawk, CO with my Whites DFX. Anyway, any feedback is welcomed. I learned something reading about trying to target based upon locating black sand with a detector. Curt

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With all due respect to both Fred and Jim who are very experienced detecorists, the big problem with this method is that there are hundreds of reasons why a detector might sound off as mineral, both above water and below. Your detector cannot tell you why - it might be black sand, but it also might be one of the hundreds of other possible causes.

A rise in the bedrock, so that the gravel is thinner - can easily cause a mineral response.

Clay layers, commonly found in many streams - can easily cause a mineral response.

Several smaller hotrocks close together and down deep in the gravel - can cause a mineral response.

Bigger boulders of mineralized rock (at least hotter than the gravel as a whole) can cause a mineral response.

Deep big trash, another common occurance in mining area streams, will respond like mineral if its really rusty and on the limit of detection.

Here is the real kicker for in stream use of this technique:

You cant detect mineral resonses deep. We all know that one of the "tricks" of not digging mineral responses or hot rocks in the gound is to raise your coil a few inches - if the response quickly dies as you raise the coil, its highly likely to be a hot rock or mineral concentration. If you are looking for black sand, your bedrock had better not be more than about 3-4 inches deep, or you probably wont detect that black sand. Most paystreaks are thin - they lie on bedrock and are only a couple inches thick (not counting parts that extend down into crevices). If you are detecting more than 6 inches above that paystreak you are not going to hear any black sand concentration. At 1 or 2 feet thick gravel (very shallow ground by dredging standards) there is no way you are going to detect a black sand concentration a couple inches thick on the bedrock.

Yet another point: Gravel by its very nature is varied and consisits of a mixture of stuff, normally with differeing iron contents. To see something significant you are going to need to set the sensetivity fairly high. If you set your mineral sensetivity too high, you wont be detecting small amounts of black sand.

Still Another point - the coarse gold portion of paystreaks may not be enriched in black sand at all. Fine sized flour gold and black sand do naturally concentrate together in a paystreak. The flows that lay down coarser gold will normally be just too fast to concentrate sand sized magnetite. If larger chunky pieces of magnetite are present (like from bean to egg size) these are the ones that will be found concentrated with coarser gold. If larger magnetite pieces are not present in the gravels, there will not be a detectable black sand "mineral zone" for that paystreak.

Like I said, I respect both of you, but I dont think detecting for "mineral" as a method of finding pay streaks is anything better than a total guess - just shot in the dark.

Chris

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  • 1 month later...

Well nobody has hit on this for you yet so I'll give you my :twocents:

I have a couple years behind the GMT and what I can tell you is I would use the stock coil that comes on it for that purpose.

#1 the smaller coil "see's" less ground therefore it should give you different readings. And I don't believe it was made for the purpose you are trying to achive.

#2 If you are trying to trace or "see" the black sand pattern in a wash the stock "DD" coil does a fine job of that, I would ground balance in the normal fashion on the side of the wash where the soil is less mineralized then proceed to swing thru the wash This will give you the readouts your'e looking for I do it all the time.

Ground balancing a GMT can be done in a couple different ways read the manual again and you will see that you can either pump it up an down or swing horizontally while holding the "GRAB" button.

Then if you like you can fine tune after that with the up/down or + - button.

Nothin 2 it

If you are really into learning more about the VLF's get a copy of Larry Salle's book "Zip Zip" You will learn even more about ground balancing and complete usage of your detector.

Hope that helped ya.

Frank, What has been your experience with the small nugget-shooter coil? I have found it to run much quieter over 'busy' ground. When (or why) would you prefer small coil over stock? Thanks.

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Frank, What has been your experience with the small nugget-shooter coil? I have found it to run much quieter over 'busy' ground. When (or why) would you prefer small coil over stock? Thanks.

Billyjoe, Never use one. I have used the larger "sierra" coil for covering more open ground and deeper penetration purposes.

All my basic hunting with the GMT involves the stock elliptical coil.

Your small elliptical coil "SEES" less ground which makes it quieter, it also lacks "depth" compared to the standard coil.

For getting into tiny cramped areas the small coil will fit in is the reason I believe most users have the mini shooter coil.

And also very trashy areas the mini will see less at a time to help you to pick out a target from amongst multiple signals.

Me I'm like a bull in a china shop it theres something in the way of where I want my coil I move the obstacle.

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All due respect to my more experienced and educated and elder comrades here but I had to throw this out there,.....

Useing a GMT or any detector that gives you an reading or hint of how mineralization is running or collecting in a desert rain water corse can be an AID to finding a worthwhile target.

Its not a guaranty.

Its another trick in the bag of knowledge that can be applied when thought of.

One ol timer that taught me some things told me one day when I was detecting in a wash and then digging some material to test in the drywasher using the detector as a sampler of the more mineralized parts of the wash, when you start seeing GARNETS in the samples from the riffle tray 'move over to the left and right of your sample hole and there will be the gold" He was right. May not ALWAYS be the case but "that the way love goes"

Some days you got ALL the girls, some days you can't even get 1.

So goes it out in the field Nuggetshootin or Drywashin or Eyeballin areas. Sometimes it makes sense and then other times mother nature doesnt even though it looks like she should.

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Hello to all, I noticed that there are a number of GMT users here so I thought I'd post here.

When you're searching for black sand deposits (the quantities of mineralisation readout), does it make a diference what coil you use? It seems that the smaller coil will give slightly different readouts over the same ground.

It is also recommended that you have to pump the coil up and down to use that feature, but this is inpractical as you'll not be covering a lot of ground. At my local goldfields today, I was struggling with this a bit, and it is an area where fine gold has been found.

Im still a beginner and I have not had my detector out in years but my last outing was with the shooter coil in a trash infested campground. I was always getting so many targets in such a tight area, 3-4 targets per short swing that i had alot of trouble using the discrimination. The shooter coil helped alot to separate targets and and allow the detector to tell me which ones were not iron. Ive heard from a few goldmaster users and dealers and they always either love or hate the shooter coil. The dealers i spoke to that did not recommend the shooter were against it for depth and coverage but were unclear on if they had actually used it. The last one i spoke to actually had the coil and used it on his own machine and said it was the only coil he uses on his GMT.

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robbor... if you go back a few posts billyjoe asked Frank c about using the smaller coil.

Frank stepped up to the plate and gave an excellent answer. The standard coil is a 5x10 inch

Twin-D. It is strong and rugged and as Frank noted the user can be aggressive in using it.

Also the standard coil is designed to match the design parameters

The Sierra Gold Max is a larger 7.5x13.5 concentric coil. It was especially designed to increase depth on medium to large nuggets. Being larger it also has increased coverage per pass. However, some loss of very small "bread and butter" nuggets is expected. Moreover, since it punches deeper and sees more soil matrix to gb out, it usually needs to be swept slower to and can be more noisy in trashy areas.

The nuggetshooter has a smaller footprint. It sees less matrix and a choice in trashy areas. Trashy areas usually are found where oldtimes camped. They camped near their claims. Also since smaller "sniper" see less matrix to ground balance out, they can be swung faster with better target and trash separation... they require less pinpointing. They are a vacumn cleaner in recovering small flakes in the top couple of inches of dirt.

Thus the choice of coil size can depend upon the many attributes regarding the local gold field.

Frank c... I love your last post! If'n we ever meet the coffee is on me... You absolutely made my day! Thanks... Jim Straight

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Yo All...regarding the Goldmaster sniping coil, here's a link to a report I did on it when the coil was being developed...I think Bill also still has it on his main page too...Cheers, Yer Unc in the Dubyah Click Here

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Uncle Ron... Wow!..This is a great in-depth report!... Does Jimmy "Sierra" Normandi of White's Electonics know about this report?

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Uncle Ron... Wow!..This is a great in-depth report!... Does Jimmy "Sierra" Normandi of White's Electonics know about this report?

Hi Jim and all...Yes Jimmy knows about this...I was participating in the final testing and development of the coil for Jimmy and Whites...He asked me if he could use some of the quotes for marketing or advertising, but I don't know if that ever happened...At the time I owned the prospecting shop in Wickenburg and had a

Whites dealership...Cheers, Unc

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Uncle... I remember back then. We exchanged e-mails regarding the GM3.

As I best remember(?)The GM/4B was an early pathfinder in being able

to identify "non-iron" Conductive Ground/Alkali from "iron" Magnetic-

Ground/Iron. This was later updated and added to the GMT... I believe

Mr. David Johnson was involved with the White's engineers in this the development(?)

By pumping the coil as if you were ground balancing the operator was able to determine the magnetic susceptability of the soil which was expressed in the terms of the percent volumn of the mineral magnetite which is found as a consituent in most black sands.

As I remember it was measured in percentage of Fe304. The Teknetics T2 also has this ability and the Fe3O4 is measured in "micro-crgs."

Thus in some instances as gold is found associated with magnetic black sand it may be possible(?) to map out channels such as the BFO's were able to do in the mineral mode.

I use my T2 to check out the ground mineralization before I set up to detect an unknown goldfield. Most ground mineralizaion is about, or less than 2,500 micro-cgs. Heavy mineralization can be approximently 7,500 micro-cgs.

I wish I knew more about the GMT's ability to trace out shallow black sand channels which can also carry gold... Over the years I have tried to do this on open ground around Sawtooth knob in northern Nevada and elewhere on a pediment with mixed success, depending upon the depth to bedrock which seems to be about 1.5 foot; more or less. Thus many possible channels are too deep.

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Thanks AU Seeker!!! :thumbsupanim

I was just wondering, as I noticed that GM2's sell for almost twice as much as the V-SAT's on Ebay.....not sure why. Is the GM2 a better machine than the V-SAT? Is there a difference between the GM2 and the GM2 Longscan?

As I said....just wondering. :rolleyes:

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