Is a PI machine really needed ?

[Danno]

I just watched a youtube video of some guys prospecting in the Australian goldfields using the SD2000 and looked like a 4500.

I noticed they were getting quite a few hits and a fair bit of gold for a weekends work.

What I also noticed is that 100% of the gold they found was laying on top, or just below the surface. Well within range of a 705 in prospecting mode and fitted with the DD 18.75 coil.

So my point being, in this area, they probably would have done just as well with a $1000 machine opposed to a $5000 one ?

Danno

 

[CladJunkie]

Well a PI machine is the machine of chose when working bad ground since they don't see mineralization. Is this really a true statement? The answer is both yes and no.
PI's basically do not respond to the typical iron mineralization such as magnetite or black sand. However, other minerals of the same family can and many times do cause a response. Iron oxides such as maghemite, clays, and other things such as salts commonly found in the ground can cause a PI to produce a rather strong signal. So, generally a very sensitive PI, normally used for gold hunting will respond to ground signals, especially if it does not have some form of ground balancing circuitry built in. I guess after finding a few gold nuggets at today gold prices you can affore whatever you like.

 

[Furious T]

Anyone who goes gold hunting on the Australian goldfields without a PI machine (with some rare exceptions) isn't all that serious about finding a lot of gold. JMHO

 

[Danno]

They must have been on a 'virgin' patch? Just that all the gold they were finding (and plenty of it, small nuggets) were only a few inches deep, mostly on the surface.

Wouldn't the 705 actually be a better detector to have at hand in these circumstances with its ground balancing and all the other features that a PI doesn't have?

I thought the SD2000s, up to the 4500s etc were all really designed for one main purpose, that is to go really deep and each new model, ie: the new 5000 would go even deeper.

where our 705s (and older PI's) can't penetrate.

Just thinking out loud, but my point is that a 705 is as good as a 4500 at finding nuggets (at depths to the limits of our 705) but probably even does a better job finding surface gold
and nuggets at shallow depths ?

Danno

 

[Furious T]

My understanding is that mineralization in the ground does not just affect a vlf detector at depth, it affects the depth to which the detector can actually reach, and also affects the detector's ability to distinguish the ground from a metal target, e.g. gold. Whilst to the casual observer it might look as if finding small shallow nuggets is easy pickings, the fact that both the people in the video you watched were using PI detectors indicates that those detectorists believed that in the ground conditions they were hunting, they needed PI machines. The 705 will find gold..in conditions which it can handle. From articles and reports I have seen the best coil to use for gold is the 10"x5" DD 18.75 kHz. Lots of other detectors will find gold, but in some conditions they will miss a lot too, and the state of the ground will determine whether they can even pick up a small nugget on the surface.

 

[Terra1959]

Gday

I have used my Xterra 70 multiple times in various mineralised goldfields in Victoria and South Australia,
I have given up gold hunting with it after finding my 1st gold - a 0.8g piece on the surface...I was lucky to find it
It is noisy beyond belief and hard to distinguish signals form falsing , only by drastically reducing Sens. can it be bearable.
If a big slug is under the coil it will be heard but small stuff is very easy to miss thinking it was just another false chirp.
Some people do use them as thats all they have but I am afraid to say that my Xterra is just not up to the task in our heavier mineralised soils.
I have heard that some parts of Northern Australia they behave themselves better.
JMHO

T59