Jump to content
Sign in to follow this  
doc holiday

Why Is Gold A Low Conductor And Silver A High Conductor When

Recommended Posts

The smooth flow of electrons in a metal is the key to high conductivity. In bulk metals the electron shells of individual atoms morph into electron bands. The outer sp bands in copper, silver and gold all conduct well, but can be effected by the next inner d band that can cause scattering (i.e. lower conductivity). “This is least important in silver where the 4d-electrons are about 4 eV away from the Fermi-level (which is also why silver is colorless). But the 3dbands in copper and the 5dbands in gold are closer to the Fermi level (absorption in the blue) and they cause more scattering with the sp electrons.” Silver wins.

  • Like 4

Share this post

Link to post
Share on other sites

The answer you are looking for is both simple and complex.  I will try to explain the simple part.  First, whether a target is a high or a low conductor is determined by the GB control and just where it is set.  If the GB is set so the ground signal is nulled, then any detected object that generates a low tone has a longer time constant than the ground signal.

This results in the GB signal channel being greater than the metal response channel.  Thus, the summed signals results in a negative response, and this results in a low tone.  

In the case of gold nuggets this means the nugget has to be pure enough, the right size and density and often the right shape or right surface characteristics.  Over the years, much of the  gold I found came from Rich Hill AZ.  Fortunately, this gold is quite pure (92% or so).  As such, gold larger than a quarter OZ was large enough to generate a low tone.  All gold smaller would create a high tone,.  Early US gold coins follow this pattern, meaning a $5 US gold coin would or could fall in the GB hole and be almost not detected.  All lower valued gold coins would be a high tone or a low conductor.

As the purity of gold is reduced, the conductivity of the gold diminishes, thus, much if not most is detected as low conductors.  A good example is the gold we found about 5 miles from Rich Hill where all the gold found registered as low conductors even up to the 1 oz nugget found.  At this site almost a pound of gold was found with many of the nuggets greater than 1/4 oz and all tested with the TDI registered as low conductors.


  • Like 7
  • Thanks 1

Share this post

Link to post
Share on other sites

Finding the amount of reduction of the conductivity of gold as it is alloyed has turned out to be quite difficult.  Fortunately, I did find some shocking information on the old PI forum that does help.  Here is that info.

Here are some numbers for copper-gold and silver-gold alloys.
The first column is the % of gold in the alloy.
The second column is the conductivity relative to copper of the copper-gold alloy.
The third column is the conductivity relative to copper of the silver-gold alloy.
% au cu ag
100 .75 .75
90 .14 .23
80 ??? .17
70 .11 .14
60 .12 .14
50 .14 .15
40 .17 .17
30 .22 .21
20 .30 ???
10 .47 .44
0 1.0 1.05
Lead shot is usually alloyed with antimony, so its conductivity is less than pure lead.

(The above info was posted by  the late Robert Hoolko).

Hi Beachcomber,
Alloying even a few percent of other metals causes the conductivity of gold to drop dramatically. Even if the other metal is a good conductor, like silver. I haven't seen any published values for the different alloys either. I have a conductivity meter which gives a reading as a percentage of that of annealed copper. A 9K ring gives a reading of 18%. Unfortunately the object has to have a surface area of about a square centimeter, otherwise you do not get enough signal to read. This is a very wide ring, so it can be done. No other rings I have work. Great for coins though, a nickel reads 5.3%


As an example from the chart we see that gold can go from a reading of 77 at pure gold to 16 when alloyed with silver such that the gold is only 75%. The 16 reading would place that same gold closer to the conductivity of lead, while the pure reading is much closer to copper.

This last post refers to a website where standardize gold alloys were listed by a company, deringerney, in 2010.

Hope this info helps.


  • Like 3

Share this post

Link to post
Share on other sites

Thanks everyone for your informative replies---I think the takeaway from all this is Dig Everything when gold hunting.

Share this post

Link to post
Share on other sites

Thanks Reg, this helps explain why gold has such a wide response on my CTX 3030 screen. 

Share this post

Link to post
Share on other sites

FWIW, it seems that silver production was down last year as high-producing lodes are increasingly hard to come by. 

The argument has been made that there will be VERY little relatively easily mineable silver left on the planet in a few decades. 

It's also claimed that at any given time there may actually be more above-ground useable non-bullion gold on Earth than silver because most gold is kept "intact" i.e. not used in manufacturing but instead kept as jewelry or bullion; OTOH, most non-bullion silver is used-up in manufacturing. The silver bullion market is incredibly small compared to gold.

Remember a few years ago when waste companies would offer free "recycling" of old computer motherboards? They were doing that to salvage the tiny amounts of gold those motherboards contained. Since silver is only about 1/80th the price of gold on an ounce-to-ounce basis at this time it's just not worth it from a financial standpoint to salvage all the silver deposited in landfills across the nation. If silver rises to a few hundred dollars per ounce, as some speculate it eventually will, it might be a good idea at that point to invest in companies specializing in the recovery and recycling of silver used-up in manufacturing. Some financial experts say that the "normal" ratio between gold and silver in terms of price should be more along the lines of 1:15 than the present 1:80. Time will tell. If it does, look for metal detector companies to begin marketing machines specializing in finding silver.

  • Like 1

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Similar Content

    • By phrunt
      Has anyone had any experience with these things? 

      Electromagnetic and magnetic interferences could be extremely annoying when you are looking for that hard to find gold nugget. Most of the noise is picked up by the search coil but a significant level of noise is being picked up as well by the sensitive electronics inside the control box.
      The control box is made of aluminium therefore the magnetic field easily penetrates it.
      To prove that, approach a magnet to the right side of your detector when switched on. 
      Millions of less obvious noise signals are interfering with your detector.  
      We have developed this Shield from the best quality material primarily used in sensitive 
      medical and scientific electronics. After years of studying and testing different materials we have found this one ticks all the boxes. 
      I have revisited the places where I've previously cleaned up and found more gold after installing the shield.
      It is 0.35 mm thick, held firmly around your control box by the armrest and  the new improved version with dual layer shielding on the right side is only 175 g!
      We have tested it on the GPX 5000 with amazing results such as quieter threshold, better GB, resulting in slightly increased depth.
      The shield allows you to increase the Rx gain by a notch or two without compromising the threshold. Use Inverted Response when hunting for big deep nuggets. 
      I noticed it on Ebay today while I was looking for a cover for my GPX.
      I have noticed I've been able to quieten down my GPX by opening the control box up and scraping some paint away where the shielding touches the casing, on one end they had scraped away paint from one screw point during production, and the other end had no paint scraped away at all by the factory so it's sheilding was basically useless.  By scraping paint away from a few areas on each end of the detector I was able to give the GPX a bit of a noticable quieten down.  I am sure on later models Minelab would of scraped away more paint but as mine is a very early model made in Australia version this wasn't done.
    • By Steve Herschbach
      We just went through a few years on constant releases of new prospecting detectors. And now the flood has subsided, with almost nothing on the horizon.
      There is the “any moment now” Makro Gold Kruzer, running at 61 kHz and waterproof to 15 feet. After that however it gets pretty thin.
      First Texas has new detectors in the works, but nothing rumored that is aimed specifically at prospecting this year, but maybe later. Right now a PI beach detector appears to be up next. Garrett - maybe they are working on it but personally I have given up waiting on a lighter weight ATX. Tesoro - nothing going to happen there obviously.
      Minelab still “owes” us GPZ owners a smaller coil but with Equinox occupying all their efforts....?
      Nok/Mak outside of the Gold Kruzer has been working on a PI for years, but absolutely no hints on it getting any closer to market.
      XP I thought might bring a version of the low cost DPR 600 to first world markets but no sign of it happening.
      And White’s? Who knows. Maybe we will see a repackaged GMT but the shine has worn off of repackaged detectors these days.
      Long story short is it often takes new detectors to stir up activity on forums. For now at least the future is looking pretty quiet. The good news is we can just focus on using what we already have to best effect without being tempted or distracted by new shiny toys! 
    • By oldmancoyote1
      Hi Steve:
      Just re-read your "Steve's Guide to Threshold, Autotune..."  It helped a lot.  Thanks.  
      I do have a question though.  I understand V/SAT.  It's about how fast autotune re-adjusts the threshold after encountering some disturbance like a target.  However, I'm unclear on how that relates to Ground Balancing and Tracking.  It sounds like they are the same.  Would you please explain that?
    • By wanderer
      What are some of the least expensive pi machines? Can used ones be found?
    • By vive equinox
      Hello , 
      It would be great if the youtubers like calabash and others  who have lot of followers make a video of that to share at maximum .
      - Take 12-15 differents coins of your country ( the coins you use all the day ) 
      -Make a pile (heap ?) with that coins ,like a little tower 
      -Keep this pile beetween your thumb and other finger .
      -Swing that in front of the coil , at 3-4 inches , the side of the coins ! 
      -Now try that with all the detect mode , not need to change factory presets ( maybe only the accept to 0,1,2 in field 2 ) , you are free to try differents settings later .
      -The only and important setting for the moment is to change frequency , try 5,10,15,20,40 and multi in each detect mode . Of course multi in the two beach and 20,40,mutli in gold .
      What is happening ?
      I know the results , but i want to know the result of the coins of USA,England, australia ,canada .... So please share your results in comments or video
      Make that with different detectors , if you have impact or deus or other who have various frequency , try to switch all frequency . 
      You can try that with HF white coil if you have , but ....
      The conclusion is multi IQ obsolete the others single freq .   It is more or less to say what calabash said in his video .
      We can debate of that .