Ask Jimmy Sierra: Best detector for finding black sand deposits


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Name: Rich

I own this model: MXT

Do I set he MXT to find Black Sand deposits so I am able to set up a sluice to find small placer gold?...or do i need a GMT or the DFX?

Thanks...best...Rich

Hi Rich, Your guess is correct. The GMT is the only detector which will measure the "amount" of black sand in an area and thus where the gold is likely to be concentrated. The GMT also measures the type or degree of mineralization ( the number which indicates ground balance) A detector actually balances to the type of ground. Thus the value, say around 77 on a GMT would be where ferrite or pure black sand would ground balance. No matter if there was an ounce of black sand or a pound of sand it would balance in the same place. Of course if there was too much to handle that is "overload" the detector NO balance would take place. but if you lowered sensitivity or lifted the coil away from the overload amount, the detector would balance with the same number. The DFX can show you a number and so does the MXT. However it is "concentration" of black sand that would indicate a good place to sluice or drywash and that can only be done with the GMT. Good luck,

Jimmy

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Name: Rich

I own this model: MXT

Do I set he MXT to find Black Sand deposits so I am able to set up a sluice to find small placer gold?...or do i need a GMT or the DFX?

Thanks...best...Rich

Hi Rich, Your guess is correct. The GMT is the only detector which will measure the "amount" of black sand in an area and thus where the gold is likely to be concentrated. The GMT also measures the type or degree of mineralization ( the number which indicates ground balance) A detector actually balances to the type of ground. Thus the value, say around 77 on a GMT would be where ferrite or pure black sand would ground balance. No matter if there was an ounce of black sand or a pound of sand it would balance in the same place. Of course if there was too much to handle that is "overload" the detector NO balance would take place. but if you lowered sensitivity or lifted the coil away from the overload amount, the detector would balance with the same number. The DFX can show you a number and so does the MXT. However it is "concentration" of black sand that would indicate a good place to sluice or drywash and that can only be done with the GMT. Good luck,

Jimmy

jimmy, thanks for the post on the gmt and mxt. Very informative.

DENNIS

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I have not met Jimmy Sierra in person, but he is well known and well respected - I even own a book of his about detecting for nuggets. I am interested to hear his opinion, but I will offer mine as well. I have been prospecting over 30 years, I bought my first dredge from Keene in 1978, my first metal detector in the mid 1980s. I own both an MXT and a Minelab GP Extreme and have found gold with both.

Prospecting for gold by tracing back sands is often mentioned in various books, but is honestly a very poor and generally unproductive method of prospecting. While gold and black sand commonly do occur together, it is not necessarily so. I have panned deposits of black sand in gold bearing rivers that contained little or no gold. I have found coarse gold in deposits with very little black sand. You are looking for gold - detect or pan for GOLD. If you want to find a gravel bank with gold that you can run through a sluice box, sample the gravel with a pan, not with a detector seeking black sand. Another problem with detectors is that the river gravel may show high iron content from just the rock in the gravel, and it is not possible to tell how much of the iron is in black sands or how much is in high iron rocks like basalt that are in the gravel. My suggestion is that trying to find black sand deposits with a detector is a waste of time, and you would be better off trying to find gold!

On the other hand, I can recommend that if you find a piece of gold in a crevice in the bedrock with your detector, it can be very worth while to take all the gravel in that crevice and pan it down. You may well find a good amount of fine gold along with maybe some smaller nuggets missed by your detector. Russ Ford and I did this with a 1 penneyweight nugget we found on bedrock in Arizona. After the one dwt nugget was out of the hole you could hear some more, smaller targets. We took them individually where possible, but ended up just digging all the gravel at that one spot - it amounted to around one 5 gallon bucket full. The total take with all the fines we took out of that gravel was right at 5 dwt, a quarter of an ounce. This is a much more useful tip on finding gold than the suggestion of looking for black sand.

The bottom line: Gold is a MUCH, MUCH better indicator of the presence of gold than black sand. :)

Chris Ralph

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Hello Reno Chris,

I have to agree with you on this one even though Jimmy is very well known and a successful hunter. I have found locations where hundreds of gold nuggets have been recovered by detectors and very little, if any black sand is present. I've also found places where the black sand is so thick you would swear gold had to be present, but it wasn't! :(

I put very little faith in looking for black sand deposits. If you want to hunt for gold nuggets, research free milling, pocket type gold deposits. I also like to hunt areas with a lot of errosion or weathering. I have other secrect indicators, but you know ... :o

Take care,

Rob Allison

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Yo, Chris, an excellent observation and explanation...Black sand is more useful in sluicing and dredging, but pretty much worthless in beepster as a primary indicator....I regularly hunt in areas where the black sand makes it almost impossible to ground balance a PI or or VLF ... However, when you're hunting with a GB2 or a Whites in known gold patch areas, the black sand can tip you off...But so can the shape of the wash, i.e. , inside turns, gentley eroded benches, etc. ... Lots of tricks of the trade out there...Good points you made...Cheers, Ron

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  • 8 years later...

Bump

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just a hint re: this old thread :). Go to the thread "I want to know Why" by Ridge Runner and go to post # 6 by GURU Steve

H. about David "woof."

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Gosh let me add. This is an old post that somehow was revised. It is about nine years old and

Both Rob and Uncle Ron are very knowledgeable regarding the black sand conditions in Arizona

and the local geological and mineralogical conditions placer gold can or can't be found

depending upon the basic types of gold placer deposits such as alluvial, eluvial, residual,

bajada and eolian deposits.

Going back to the original post in this thread, it seems to be mostly about the ability of the

Gold Master Tracker to follow the black sand; nothing more or nothing less (and as we all agree

it is limited to the depth of the of the search-coil); and the coil certainly cannot punch down to China

as the GMT is a VLF type detector operating at 50 kHz.

With this said... let this electronic plus or minus informational thread continue to roll along...

My Best to All and Yours..... jim straight

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Gosh my bad: In my last post I said 'revised' but meant 'revived'. Also I left off mentioning that

Chris (Sorry Chis), is in Nevada and not in Arizona and black sand is not known to be as

fierce in Nevada; but Nevada is known to have more alkali. Also I should mention that David Johnson

as a freelancer added the ability to 'follow the black sand' to the Gold Master Tracker. jim

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Agree Rob. Though I do know a guy who was asked to find some highly mineralised reef refuse that was full of gold but inadvertently used as some road fill near a mining site here in OZ. The person who asked him to do it told him he would give him a share of the finds. Well the guy found it with the GMT but was told by the guy that they couldn't recover it because of some mining problem over the area. He was lying and got 20 oz of gold and the GMT guy got zilch! Apart from that though I don't know of anyone using it to find any other deposits down here.

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Roo... Do you know if'n the guy was using the "follow the back sand" setting in the GMT? Or was

he just lucky.

Actually those in the know have learned to "follow the drywashers" as the operators usually seek

out concentrations of black sand seams in the hopes they are metallogenetic.

Accomplished gold panners and those using crevice tools to work seams in the Motherlode and else

where sometimes have been doing pretty good... The Chinese were especially good at sinking

a vertical drift and then in following more horizontal gold bearing (pay-streak) leads as long as the

"back" and "ribs" were competent and their candle would stay burning. But if the flame got "punky"

they would stop...

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He was using the mineralisation numbers from memory. The ground he was searching showed a big difference in the numbers in a certain area from the rest. Stood right out. He was told they couldn't go back to the area but ran in to the mine manager a number of months later who said "hey, that machine of yours worked good, ******** got 20 ounces from that throw out you found".

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Roo...by the mineralization numbers do you mean the phase number of the soil? To say it another

way; the number displayed on the visual screen when the GMT was ground balanced to the soil?

I believe the phase number is a technical term for the number that is flashed on the screen which

can indicate the TYPE of ground (under the search coil) that could be associated with higher

concentrations of magnetic (magnetite) black sands.

As an example if a VLF detector (i.e., the GMT) is calibrated to ground balance between '0' to '100,'

wet alkali soils will balance out very close to '0' in the scale. Raw metallic iron will read about '5-25.'

Then the various clay-iron rich brownish-reddish-and yellowish to whitish soil mixtures will typically

register around 40 to a high of 75 or more on the screen.

Thus, it could have been your friend found that the soil that carried the placer gold read numerically

higher than the usual in a certain area, such as over 75 on the screen and as the throw out was also

a metalliferous soil. Just my thoughts.... And I have no issues with any of the prior posts on this thread

and fully agree with them; but also looking at it as a 'newbie' who does not understand anything

other than prospecting with a detector such as a GMT. More later tailgate jim straight

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Yes, I believe those were the numbers he watched Jim. The gold in the crushed up ore was all fine and he never actually detected one bit with the GMT amongst it all. He found it by numbers. He wasn't looking for soil as such that would hold the gold, he was looking for the crushed up ore. The track was made up of previously crushed up rock and quartz which had held no gold from the site, but the mine manger who was new at the time and didn't realise they were on a good part of the load needed some track fill and crushed up some rich stone and used it. The mine guys were on to such rich stone, which they actually knew of, that it wasn't worth their time chasing down where they had dumped just several ton of it and so let the weasel guy have a go at it. Weasel guy 20 oz richer, GMT guy stooged.

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I have been thinking too that you could perform a similar thing with a Minelab X Terra 705 by having it in Auto track and then hit the ground balance button and bounce the coil, so to speak, along the ground watching for drastic number changes.

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You are right. Barnicle Bill who posts on the Tesoro forum back a couple of years ago

posted how to do this with the x70 and 705. Likely the post is lost in the zillions of posts. This trick

can be adapted to the original Teknetics T2 as just one example.

However it was first applied to the GMT and there are GURUs out there that have used it and

find it worthwhile in metallogenetic areas.... But for reasons some of the most positive users

are silent about the GMT's ability. I'm sorta sticking my neck out by bringing this post to life

and I truly appreciate way2cools last post.

Rob who's forum I'm posting on not only sells VLF's as well as the Pulse detectors... VLF/Pi

can co-exist together and enhance the owners chance of success. Ditto Bill Southern too.

Roo... many years ago I exchanged e-mails with kiwi who was in New Zeaand and have lost

track of him... and I'm a great longtime fan of Doug Stone beginning in the 1970's when Peter

Bridge started the detector's success in Australia which slowly has spread throughout the world.

More later... jim

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way2cool... Thanks for thanking me for bringing 'new life' back to this thread... Variations of it have been discussed on

other forums over the years... This subject for some reason is akin to politics, religion, and sexual preferences. It has

been a "hot" topic and notice how many times this thread was visited with only a few actual posts...

Actually it is not 'such a much' and just a software tool that can aid a newbie to get up to speed in successfully finding

potential placer electrum (gold/silver) that is often associated within the various metalliferous black sands. Hey, even

scheelite can be recovered by drywashing as it has a sg. of about 5-6 and much of the black sands are simply ferro-

magnesian minerals that are more resistant in weathering and are usually found to have a sg. from about 3.2 to 5.0

depending upon their mixture... So what is all of the "hullaboo" about...???? :wacko:

Remember placer gold is usually not pure and vary in purity as electrum 600 to 900 fine and there are many basic types

of placer deposits so I'm also saying just re-saying what the other posters in this thread have already said....

But keep in mind if you happen to have a VLF type has the software it does work bigtime. And those of you who happen

to have a copy of the revised September 2010 or the latest July 2013 update of my booklet "ADVANCED" that also has an Appendix on Meteorites but focusing on the stony chondrites that are often associated with placer gold....

And on pgs xv-c1 and xv-c2 this software ability is explained... and both Rob and Bill have these books for sale... And for

those of you who will attend the various GPAA gold shows there are many ADVANCED September 2010 copies yet to be

sold....

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  • 2 weeks later...

Also I might add Chris Ralph published a "complete guide to the art of prospecting." It was copyrighted

in 2009 and the first edition, Fists Full of Gold, was in print by September 2009.

I mention this outa fairness as in my last post I mentioned pages xv-c1 and xv- c2. which could help to explain Jimmy

Sierras post. And again I will add: All of the above discussions are good... There is no right or wrong simply because

there are many basic types of gold placers and they can grade into each other and the hardrock source of the placers

are diverse. So gold may not be found where geology may indicate; but it can be found most anywhere and that is why

it is so elusive... tailgate

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