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Metal Detector does not react to material that attracts magnet


Dusty Slim

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There must be a simple answer to this, but for the life of me I can not figure it out.. so I came to where the experts are :)

I have some material - call them rocks - found on my claim in Arizona. They are dark black, very heavy and strongly attract my rare earth magnet. [see picture] This attraction is so strong I can almost drag the largest one across the table with my magnet tied to a string..

So here is my question: Why does my Eureka Gold detector act like nothing is there when I pass it over these "rocks"? I have tried every setting and have it set to "all metals".

I would think that if a material attracts magnets, it would set off any detector. What am I missing here?

BTW, I asked Minelab and they were unwilling to answer a question and just directed me to my "local dealer". This did not make me very happy with Minelab..

Thanks so much in advance for any information..

post-27096-0-09717500-1407779708_thumb.j

Edited by Dusty Slim
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I would get somebody who has another gold specific VLF detector and have them pass over it with the machine and see what it does.
Like a Gold bug or whites gmt or Tesoro super track
See if possibly the other detector(s) respond or not

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I'm guessing magnatite ... Cheers, Unc

But magnetite would set off the detector - correct?... My detector "seems" to be working well.. I found a very tiny boot nail burried about 3 inches down with it just the other day.. and lots of lead shot.. and it sings very loud on my solid gold ring... so it just befuddles me as to why a material that is so attractive to magnets is invisable to the Eureka Gold detector... My 1/2 rare earth magnet snaps so hard against the big rock that I am afraid I'll pinch my fingers.. that is how strong the pull is...

I gound the smaller one with my Dremel and the inside looks like solid iron.. [see photo]

I'll see if I can find anyone around this area with another gold specific VLF as Frank C suggested..

The other thing is these three "rocks" are the only ones I have found on my 20+ acrea claim.. and they were within 3 feet of each other.. they are very "alien" to the rest of the geology on my claim.. but I did find them in the bottom of a very narrow and steep wash.. so maybe they washed down from higher up somewhere..

post-27096-0-49281300-1407785342_thumb.j

Edited by Dusty Slim
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The rocks certainly resemble magnetite (i.e., ironstone). My GB2 would scream bloody murder if I got within a foot of those bad boys you've photoed. I am not familiar with the workings of a Minelab Eureka Gold machine so I have no clue as to why your detector does not react to such a dense concentration of iron. Have you tried throwing down a gold nugget underneath one of your ironstones? What happens then? Just curious.

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The rocks certainly resemble magnetite (i.e., ironstone). My GB2 would scream bloody murder if I got within a foot of those bad boys you've photoed. I am not familiar with the workings of a Minelab Eureka Gold machine so I have no clue as to why your detector does not react to such a dense concentration of iron. Have you tried throwing down a gold nugget underneath one of your ironstones? What happens then? Just curious.

I'll give that a try.. maybe I found a new "stealth" or "cloak" stone.. I can sell to the Department of Defense... but as heavy as these babies are, I doubt is would be good on fighter jets...

Yea, makes no sense at all why these do not set of the detector.. but Minelab would not even attempt to comment.. weird - and - very poor customer service.. I will buy from Garrett or another company when it comes time to replace this Minelab unit..

The other weird thing like I said is there are no other "rock" like these on my entire 20.66 acre claim.. it is like someone placed them there...

Maybe Captin Kirk time traveling... just to tease this old prospector..

Thanks for the comment

DS

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Hi Slim,

Any experienced meteorite hunter would see why your very magnetic rocks won't sound off on your detector. One of your detector's features

is "Accutrak" which is an automatic ground balance. If an object is mostly mineral iron/iron oxides, with little or no metallic iron or nickel, your detector

deletes the signal as ground mineralization. The Eureka Gold is known for it's "Iron Mask/Iron Reject" programming, and the only way around it is to

turn off the auto ground balance (Accutrak), if the detector allows it. I have seen many people with a wide variety of detectors from different makers

complain that there are no more meteorites left, after a day at Gold Basin or Franconia, but when I check their machine, their auto ground balance is on.

They would have saved battery strength and achieved the same result, if they had just not bothered to turn their detectors on at all. If you can eliminate any iron mask/iron discrimination, you'll hear your ferrous ore loud and clear.

Example: I have a bucket of silver ore (66+ ounces per ton) from a mine in Colorado that the locals have completely ignored, because the ore also has enough

iron minerals to make the ore chunks jump to a neodymium magnet, so their auto ground balance blanks the signal out as ground mineralization. There was a nice silver nugget hiding in one of the pieces that I crushed. I would have missed that, if I was using any form of automatic ground cancelling.

Sometimes an area has so much iron trash, that you have to use the iron reject. Just remember, that you're also eliminating some possible targets.

Good Hunting, Ben

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That stuff is very common around Wickenburg...I've got a few I bothered to bring home and they are identical to your samples ... If you do a scratch test on ceramic or even on a piece of quartz or even concrete, I believe you'll get a red streak ... It streaks really easy so you'll find you can write "LEAVERITE" in any language you want!!! :4chsmu1: Cheers, Unc

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If you build a Detector and set up the GB using a peace of Ferrite Rod as a sample., they will not see stuff like that. Adjust your GB and I bet they will show up.

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  • 6 years later...

I have the same stone it attracts a magnet ( strongly ) but not a metal detector .......  its dark with reddish quartz in it and very heavy ........ it has no magnetic pull at all ? my pointer reads a staple but not this stone ?????????? rock was found in area of monzonite - scratch test leaves a dark blackish-brown on ceramic - seems to have a outside polish similar to being burned ? Dusty Slim's photo looks the same as mine - I've had this rock years now and still have no clue of what it may be ? may send an image when I get a PHOTO ..................

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1 hour ago, bigwall said:

I have the same stone it attracts a magnet ( strongly ) but not a metal detector .......  its dark with reddish quartz in it and very heavy ........ it has no magnetic pull at all ? my pointer reads a staple but not this stone ?????????? rock was found in area of monzonite - scratch test leaves a dark blackish-brown on ceramic - seems to have a outside polish similar to being burned ? Dusty Slim's photo looks the same as mine - I've had this rock years now and still have no clue of what it may be ? may send an image when I get a PHOTO ..................

If it is magnetic and leaves a streak of grey to black it is magnetite. If it leaves streak of brown or red it is hematite. These are common iron minerals.

It does not cause a reaction on your detector because it is not conductive. 

Metal detectors generally do not react to non conductive minerals. If they do it is usually a "negative" signal.

They are designed to find metals. Not minerals. That is why they won't beep on your rock. They purposely ignore minerals and only give a positive signal on conductive metal.

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Minelab’s answer is based on the fact that they do not support the eureka since it was discontinued long ago and customer service has no info on it, but most dealers do and have used it.

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4 hours ago, bigwall said:

looking at my heavy stone with a magnifying glass i see that it's a mineral  ..... a hydro thermic rock ?

If it is heavy stained quartz with lots of iron yes. It sounds like a hydrothermal deposit. Probably an oxidized hematite gossan. That is classically formed at alteration zones in metamorphic rock or at contacts between igneous and metamorphic geology. 

That is just what a gold prospectors looks for. 

Do you have a photo of the rock?

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  • 3 months later...

https://photos.app.goo.gl/CbpToKfhAQ5FrX5R9

On 8/11/2014 at 2:59 PM, frank c said:

I ran across similar incident here in Ohio?

 

On 8/11/2014 at 2:59 PM, frank c said:

I would get somebody who has another gold specific VLF detector and have them pass over it with the machine and see what it does.
Like a Gold bug or whites gmt or Tesoro super track
See if possibly the other detector(s) respond or not

 

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