Gold/Silver coins detection

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Mark Messa

Member
Joined
Nov 4, 2015
Messages
23
If you have a small bag of coins, till what extent a metal detector (or other kind of detector) can identify whether you have some precious metals in it or not?
 
justinhcase said:
"Optional Reception of Announcements by Coded Line Electronics
Socrates and Apollo's Oracle at Delphi: "The Delphic Oracle exerted considerable influence throughout the Greek world, and she was consulted before all major undertakings"

Even so, I'm removing it from all my messages.
 
Mark Messa said:
If you have a small bag of coins, till what extent a metal detector (or other kind of detector) can identify whether you have some precious metals in it or not?

It's my understanding that metal detectors are not reliably discriminating enough to say this is gold and this is nickel, etc.

An XRF scanner can, if properly maintained and used by a skilled person, determine the surface content of the coin. Whether the coin is the same composition as the surface throughout is another question though.
 
The detector I use can definitely tell me the difference between copper, silver, and nickel coinage. I gives me two readings based on the ferrous and the conductivity of the target. Just passing the machine over a coin in the air, I can tell the difference. In the ground, things get trickier, as you have interference from mineralization. But quite often I can guess correctly whats coming out of the hole. Now fineness,etc. no way. The machine I use is a Minelab Explorer 2, and I have 10 years of experience on that machine. XRF for fineness, or if you don't want to spend $30,000 for a one of those. Go to your public library and look them up in a world coin catalogue for free. (Krause World coin Catalogue) Every world coin is listed along with its metal content and fineness. Sometimes even its actual silver weight. Or actual gold weight if you're lucky. Look them up. It won't take long to find out what's good and what's not. Good luck
 
Minelab explorer 2 is one of the best detectors around. It is here for quite some time but it is still one of the best. I know what I am talking about, I too have one. :mrgreen:
 
Metal detector discrimination systems are based on size and conductivity. So they can distinguish between iron (low conductivity) and copper (high conductivity) easily. They do a poor job between a copper cent and a dime -(both high conductivity and roughly the same size). They distinguish fine a dime from a quarter (both high conductivity but significant size difference). They do poorly distinguishing between silver dimes and copper clad dimes as they are the same size and both silver and copper are high conductivity. Gold is only a fair conductor, so it is distinguished from silver and copper (high conductors) and iron (poor conductors) but gold is not easily distinguished from lead or aluminum, both of which are also fair but not great conductors the same as gold. Many detector operators tune the discrimination on their detectors so that aluminum pull tabs (a common trash item in many parks) are ignored. The problem with this tactic is that you also tune out most gold jewelry at the same time.

To answer the initial question, if you have a bag of coins of mixed make up - combining many different types - copper, nickels, silver, gold - the detector sees an average of all of them. I have dug pocket spills with multiple coins and you get a discriminator reading that is a combination of all. So no detector will tell you silver if you have two nickels and a silver dime as the nickels will lower the average reading so that the total might indicate zinc cents even when the coins are nickels and a silver dime, because the average of all looks like a couple zinc cents to the detector.
 
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