Detecting Tiny Gold Nuggets with F75

[GrantT]

So, back from some holidays which included some metal detecting and gold panning and other related activities.

I did get some gold, but by winning a chili cooking competition for the panning club, not by detecting/panning (well, we did pan some light flour/dust gold).

Anyways, figured I would use the little nugget as a test object to help fine tune my skills. I dropped the little nugget in the grass (in a tiny glass vial) and it pretty well required the stock coil to be within an inch to detect it. Any ideas if that is as good as it gets? I've tried numerous settings, sensitivities, tones.

So, while the documentation seems to indicated the F75 is usable for gold prospecting, what are the real limitations? Would have to be significantly larger nuggets? Some setting I need to use specifically. Or, realistically, is this type of detecting a waste of time with an F75?



Grant

 

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[Kray Gelder]

The reason gold is used in sensitive, high end electronics is it is an excellent conductor of electricity and offers very little resistance to the flow of electrons. When gold is hit by an electric flux field, it is transparent, or nearly so, and barely disturbs the field. This disturbance is what a metal detector detects.

When I hear hobbyists talk about gold being low conductivity, and that is why we don't pick it up, it's actually just the opposite. It is highly conductive. When we find gold jewelry the detector is seeing the non gold alloy, mainly, the same with gold coins.

That's my understanding of conductance. Others here who have experience shooting nuggets and find raw gold on a regular basis may chime in. Good luck.

 

[GrantT]

Thanks for the explanation - being an electronic engineering tech, that makes perfect sense to me, and also explains the specialty gold detecting machines, techniques etc I see as well.

 

[Rick K]

Gold, even pure 24k is not an especially high conductor - its use in electronics is due to it’s extreme corrosion resistance.

Alloying any metal can radically change its conductivity. Alloying gold a somewhat high conductor with silver - about the highest conductor - usually results in a medium conductor alloy.

Here is some data from a chart -

Electric conductivity (10.E6 Siemens/m)​

Silver	62,1
Copper	58,7
Gold	44,2