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Pocket Full Of Kryptonite (pennies)


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13 hours ago, kac said:

Updated, just looked it up and they had 2 different alloys

For sure, they started out with 12% nickel (remainder copper) and switched to 'modern' composition of 95% copper in the sometime in 1864.  Those definitely give different dTID's.

What I (and F350, and Tim) were speculating was how different TID's are for all the 95% copper pennies from 1864 to 1982.  There do seem to be variations even among those, possibly (my contention) due to variations in the composition of that last 5% (which the mint didn't delineate, until 1962 anyway).

Another big uncertainty in my mind is how much being in the ground changes dTID's.  Obviously the Zincolns get eaten up so they vary noticeably, but do other coins?  There was a big discussion a couple years ago as to what causes the variation in Jefferson silver-composition nickels ('Warnicks') dTID's and that was my thinking then -- leaching out of the manganese.  Others thought differently -- including alloy variations at the mint, and no solid conclusions were reached.

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13 hours ago, kac said:

Didn't the content vary over the years? I have found IH with very low numbers and some with high numbers. Think I need to check and sort by year the ones I have and see what the differences are.

You know way more on the coins GB.

Updated, just looked it up and they had 2 different alloys over the years which may explain much of the variation on the IH's anyways.

https://en.wikipedia.org/wiki/Indian_Head_cent

How accurate the mixes where are probably negligible on the machines ability to tell the difference other than the major change of alloying between the 1859-1864 and 1864-1909.

 

Don't forget that an ingredient like "copper" can vary in TID, depending on where it was mined.   Because of trace minerals that exist in various parts of the USA.  For example Rose gold vs yellow gold.  Each is equally gold, but they have slightly different make-up colors, d/t the trace minerals of where they were mined. 

 

So too is it the same with copper :  Uncle Sam might have been buying his copper on the open market (wherever was cheapest) in ... say... Montana during a few decades of the 1880s/90s.   But then switch to Idaho where a new mining strike of copper was the new source, etc.....  

 

Because notice that wheaties from the early teens sound different than wheaties from the '20s, vs wheaties from the 30/40s, etc.... (not to mention the sickly corrosion/color that 30s to 50s wheaties take on, while teens/20s wheaties take on a desirable green patina).   This is true even though all the wheaties and IH's supposedly had the exact same composition .   Thus it's apparently the trace minerals in the ingredients, that make for the differences we see, and our subtle TID differences.

 

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1 hour ago, Tom_in_CA said:

This is true even though all the wheaties and IH's supposedly had the exact same composition .

I disagree.  The mint reports (paraphrased) 95% copper with the remainder tin and zinc.  If trace impurities can lead to different dTID's, then certainly varying tin and zinc at the few percent level should be even more noticeable.

I swear I'm going to do a study on this.  I don't have an extensive collection of Indian Head Pennies (IHP's) but enough Wheaties (other than ones I've found with a detector) that I should be able to get a better handle on when variations occur.  Unfortunately (in this sense anyway) they are locked away at the bank.  If I had easy access I'd do the study today.

I've read a fair amount about gold purity back in the California Gold Rush days (say prior to 1860) when there were several private mints producing gold coins due to the lack of official USA specie making it out to the West.  From what I've read, the assayers and refiners there (working in modest confines) were very good at getting the composition&purity accurate.  Of course you're talking about copper.  I don't know if similar care was taken at the mint with that metal.  But the USA mints even back much earlier than the middle of the 19th Century were quite persnickety (official government word 😁) when it came to precious metal compositions.  Would they have been lax with their base metal tolerances?  Maybe, but it doesn't strike me as going along with the attitudes of that time period, particularly for such an organization.

I'm surprised this hasn't been worked out years ago.  Hasn't discrimination been accurate for 15-20 years?  I mean I've seen people say they can tell the difference between a 95% copper cent, clad dime, and silver dime.  If accuracies that good can be surmized, surely the differences we're talking about (more than a couple ticks on the Equinox scale) should have been noticed, leading to investigation.  I've also seen complaints that the Equinox doesn't have as accurate dTID's as some other models.  What the hell, owners of those super accurate detectors??

IMO this is more than an esoteric discussion.  If I'm missing IHP's because of too strict of a discrimination requirement I want to know,... yesterday!

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Metallurgy back then was not as precise. They melted proportions of ingots to get the percentages but those ingots and the exact amount and impurities from crude refining techniques must have played a little bit in the quality of the alloy. Unlike today where companies have better ways of analizing the metals. With that being said I seriously doubt a metal detector can really discern the slight differences on them unless the mix was drastically different such as the year changes.

I believe ground conditions play more of a roll in tid's and emi than most realize. I heavy emi wobble must have some impact on the machine if the signal is being interupted giving unsteady numbers and hot ground vs dry ground effects conductivity. Add in minerals and I am amazed how well these machines do.

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If anyone wants my help with this, y'all can PM me with specs on how you want it done. I can take what wheats and IHPs I have and check 'em. Of course since I have a 600, the settings would not be exactly the same. 🤔😀

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Just lay them out and see how they read, shouldn't matter what detector really as it is a comparison between coins not detectors right?

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5 hours ago, GB_Amateur said:

IMO this is more than an esoteric discussion.  If I'm missing IHP's because of too strict of a discrimination requirement I want to know,... yesterday!

Exactly... GBA.  This is the essence of where my detecting is right now.   The alternative is to dig everything over a 9.   Unfortunately my IHP collection wouldn't make a good statistical sample.  But I'm willing to purchase sample size of them in the name of science.  ~Tim.

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14 minutes ago, Tiftaaft said:

The alternative is to dig everything over a 9.

I'm just a "noob with a stick", but that's pretty much what I do. Many of my best buttons are 7-23. Even found some 3s. Concave Tombacs with iron shanks exhibit the 3-8 behavior particularly.

The "discrimination" I go through is first to try and get a repeatable signal, sometimes lift the coil a foot above the target, but mostly do a complete 360. If the signal acts a certain way I will dig it. I've learned to distinguish between aluminum "all over the place" and other metals. I also use 4 and 5 khz, which often makes iron iron. I run the detector in all metal almost all the time.

Another bit would be after I've been in a certain area  for a while I pretty much know what I'm gonna get.

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