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Terrestrial Use Of Impulse AQ

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I will make a video soon, I detect in the wet sand, a gold ring 18k of 2grs at 25 cm below a bag of 10Kgrs of volcanic sand 325,000 x 10 ^ -6 SI + 1 Kgrs of 100% iron powder in bottle + a few iron nails.





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16 minutes ago, Steve Herschbach said:

This equates to around a 3.0 grain gold nugget, which for me is plenty small. There are many places in Nevada in particular where there are gold nuggets larger than this and where the ground is not very mineralized with magnetic minerals. There are however large areas where alkali salt really troubles some detectors, like the GPZ 7000 in particular. A detector tuned specifically to work on alkali/salt while still having sufficient sensitivity to small gold may work very well in some gold nugget locations, salt flats in particular. There may be areas where hot rocks prove problematic, but there will be areas I am sure where the Impulse AQ can find gold nuggets. I plan to be one of the first to find out. :smile:

The photo below has 24 grams of Nevada gold I found with the GPZ 7000, with none of it exceptionally large or small, but all more than the 0.2 grams we are talking about as a cut off point for the Impulse AQ.


It's very interesting, I didn't know at all.
They keep repeating that for the USA and Africa, we have to find more small, 1 grain, 1/2 grain and 1/4 grain if possible.

While in the field I have a lot of prospecting friends who tell me the opposite, they want to look for big nuggets larger than 2 grs.

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The reality of naturally occurring gold nuggets is that the smaller nuggets are more common than the larger nuggets. The larger nuggets are also easier to detect. Unlike jewelry, natural gold except in active placers does not replenish. That means that in order to sell metal detectors the ability to find the small gold that is left is becoming ever more critical.

However, if you are prospecting for an actual income, either full-time or more often part-time, as is true for small numbers of people in Australia and the U. S. and in far larger numbers in the third world, there is the reality of diminishing returns. I have run my prospecting as a business licensed for profit operation since 1979, and turned a profit in nearly all those years. I have only shown a loss a few times, typically when making large equipment investments in a single year. In most years I have all my equipment and costs are merely food, travel, etc. Since I work for myself there is no labor expense per se. Yet the hours do matter to me. I am only willing to devote so much time to prospecting and only if it makes a reasonable return or at least breaks even.

My cut off point has declined over the years as the price of gold has gone up, and was last set at an average of 1/2 ounce per week or about 2 grams a day, figuring at least 50 hours of detecting in the week. To make this happen I need to be seeing at least half gram and 1 gram nuggets (or larger) turning up now and then. To make it on sub-grain gold I would have to be parked all day in one place using the detector to find tiny bits at a fairly constant rate. I once detected nearly 100 nuggets in one day, all under a few grains, in a 10 foot area. That made my half ounce for the week. The thing is, if that is the situation a washing device like a high banker or dry washer usually makes more sense.

There are places where there is a lot of small gold, and rules make using anything but a detector difficult. I have no doubt in Africa some people exist on just the tiny bits, but they live on nothing compared to us.

When full time detecting one has to be searching for new ground constantly. There are many days with no gold. So when a few nuggets do get found, they need to be good enough to cover all those non-productive days.

Hobbyists on the other hand just want to find gold, any gold. They will spend a great deal of time and money to find a few tiny nuggets. That’s who buys most detectors in the U.S. The problem for me is I am one of the older hard core more serious types. If all I want to do is find stuff for fun I’d as soon go to a nearby park or beach and look for jewelry, and be home for dinner. Real prospecting for me means weeks or months in the field at a time, and lots of work. I have found many pounds of gold nuggets over the years, so simply finding a gold nugget is no real challenge for me. I almost never come home empty handed if I go nugget detecting. However, I am finding it hard to justify the time spent to use a metal detector to find gold nuggets and am slowly shifting more to doing it for fun.

Long winded explanation but the bottom line in my opinion is there is a place in the nugget hunting world for a detector that can handle alkali conditions, and that by default means small gold will be lost for reasons we have already covered. Tune out the salt, you lose the small gold anyway. But many gold nuggets do hide in alkali conditions.

The other lesson there is that having a salt compensation mode would be very useful on the gold prospecting version of the Impulse.

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Here are some MS values for minerals from the same table. Nice collection of hot rocks Alexandre! Thank you for inventing the Impulse AQ!



Magnetic Susceptibility Range (10-6 SI)1



















1.       Compilation from Hunt et al. (1995)

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Any prospecting version will have to deal with Australian ironstone....the stuff from Western Australia is legendary. Small pieces will jump an inch to a strong magnet, will deflect a compass needle and outcrops struck by lightning will fuse together into a smooth mass 😳

But it is often a good sign of gold being nearby.......generally speaking, VLF’s go to these areas to die a painful death and you will find more gold swinging a golf club.


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I will make a video soon, I detect in the wet sand, a gold ring 18k of 2grs at 25 cm below a bag of 10Kgrs of volcanic sand 325,000 x 10 ^ -6 SI + 1 Kgrs of 100% iron powder in bottle + a few iron nails.


Alexandre , if you add small bits of nails to your mix , say  5, 10 , 15 , 20, and 30mm length , will the AQ recognize them as ferrous or as good targets ? I ask the question because I think that the conductivity of such bits of nails is close  to a gold ring conductivity. In summay ,the AQ éliminâtes iron powder and nails this is ok , but what about intermediate conductivity targets like bits of nails ? Thanks for your answer 


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