Indian Head vs Copper Lincoln Mystery

[Iron Buzz]

1864 - 1909 Indian Head Penny : 95% copper, 5% zinc, 3.11 grams
1909 - 1982 Copper Lincoln Cent : 95% copper, 5% zinc, 3.11 grams
1982 - 2014 Zinc Lincoln Cent: 97.5% zinc, 2.5% copper, 2.5 grams

So... why do those Indian Heads ring up with the same ID as a zinc penny? On my XP Deus at 18K, a copper Linc reads 90-91. An Indian Head and a Zincoln both read 85-87. Why?

 

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[Electricfrontporch]

Also if you want another conundrum.
Put two nickels together and test discrimination or ID.
It's a perfect pull tab signal.

 

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[TerryC]

Iron Buzz... one more thing that might help. If you "plant" a silver dime directly underneath a copper penny, you will most likely only display the copper penny. Moist, mineralized soil (high in iron oxide), will probably give you a display somewhere in between copper and silver. There is no such thing as perfect conditions, hence the display can only give an educated guess, based on the presented conditions and the state of its technology. A fancy way of saying the current VDI circuitry is not quite "there" yet. The VDI cannot "see" through the outer skin of coins. I had a target display that was jumping all over with different angles of the coil sweep. I normally don't dig such targets. I did, and found 65 cents of assorted coinage in the one hole. The display was confused by the copper, nickel, and silver coins. A pretty good "haul" for a jumpy display! I hope I haven't made my answer to your question just more confusing. TTC

 

[TerryC]

Also if you want another conundrum.
Put two nickels together and test discrimination or ID.
It's a perfect pull tab signal.

AND gold will very often ring in as the same as a nickel. Go figure! TTC

 

[Iron Buzz]

I did a quick unscientific trial on three non dug cents. A 1908 Indian, 1956 wheat 1981 Lincoln and a 2009 zinc Lincoln with my T2. The Indian came in at 79, the 1956 at 83, the 1981 at 83, and the Zinc at 78. Really odd, no idea why.

Yes, that pretty much matches what I'm talking about.

 

[Iron Buzz]

Ever tried non dug examples in an air test? Might be interesting to see if it has something to do with having been in the ground longer, maybe something to do with the zinc leaching out?

Yes. My post is based upon air tests as well as real life experience. And with multiple coins. It is consistent.

 

[Iron Buzz]

Do you think your thinker is thinking too much here maybe? As much as I too wonder about VDI's and tones and all at the end of it I just hear a tone check the VDI and dig it. Time and experience has led me to know the language whichever machine I am using is speaking to me pretty well. I try to avoid thinking about all the inconsistencies with the technology and just dig the targets. I spare racking my brain on more serious issues. Have fun and dig that beep.

I have a curious nature. I am not asking because it will help me metal detect. I am asking because it doesn't make sense.

The responses I'm getting lead me to believe that I may not have clearly stated my question. Let's forget about the Zincolns. My real question is just about Indian Heads vs pre-1983 copper Lincolns. Same size. Same alloy. Same weight. Different readings (TID, sound... whatever... different phase shifts). Not only have I tested and verified this with several different coins, but even XP's TID chart in their manual shows IHs reading differently than copper Lincs.

 

[diggummup]

I'm glad I always dig all targets, for the most part. That's all I got to say about that.

 

[l.cutler]

I have a curious nature. I am not asking because it will help me metal detect. I am asking because it doesn't make sense.

The responses I'm getting lead me to believe that I may not have clearly stated my question. Let's forget about the Zincolns. My real question is just about Indian Heads vs pre-1983 copper Lincolns. Same size. Same alloy. Same weight. Different readings (TID, sound... whatever... different phase shifts). Not only have I tested and verified this with several different coins, but even XP's TID chart in their manual shows IHs reading differently than copper Lincs.

Yes, I follow you, and I would also like to know why. If I can find a couple, I would like to try a 1909 Indian and a 1909 Lincoln. maybe the amount of zinc used to vary a little.

 

[TerryC]

Yes sir, Diggum! Most straight forward answer to a complex question. I like it. TTC

 

[Iron Buzz]

Yes sir, Diggum! Most straight forward answer to a complex question. I like it. TTC

Not really. As I said, this is not about hunting them. I'm not having any problem finding them. I am simply asking "why".

 

[TerryC]

Yes, I follow you, and I would also like to know why. If I can find a couple, I would like to try a 1909 Indian and a 1909 Lincoln. maybe the amount of zinc used to vary a little.

Cutler, If you are as curious as the rest of us.... call the coin shops or troll the internet until you find the right coins. That's also a form of research worth trying. TTC

 

[TerryC]

Not really. As I said, this is not about hunting them. I'm not having any problem finding them. I am simply asking "why".

Even though all here sincerely want to help answer your "why", too many answers tend to "muddy" the question. TTC

 

[l.cutler]

I tried a 1909 Philadelphia Indian cent and a 1909 vdb. The Indian came in at 79 and the vdb nearly the same at 80. I suspect that there was just a little more zinc in the earlier cents.

 

[Iron Buzz]

I tried a 1909 Philadelphia Indian cent and a 1909 vdb. The Indian came in at 79 and the vdb nearly the same at 80. I suspect that there was just a little more zinc in the earlier cents.

Huh!! Interesting!*

According to this site, both IH's and Lincolns (wheat and otherwise) are 95% Copper - 5% Tin and Zinc . I've never seen zinc mentioned anywhere else as a part of the alloy. Maybe IHs had more zinc and less tin, and Lincs just the opposite?

*I didn't know about VDBs before. Thanks... now I have to go through my pile of Wheaties to see if I have any! LOL! Such is life.

 

[b3y0nd3r]

Huh!! Interesting!*

According to this site, both IH's and Lincolns (wheat and otherwise) are 95% Copper - 5% Tin and Zinc . I've never seen zinc mentioned anywhere else as a part of the alloy. Maybe IHs had more zinc and less tin, and Lincs just the opposite?

*I didn't know about VDBs before. Thanks... now I have to go through my pile of Wheaties to see if I have any! LOL! Such is life.

Did you read my response? The answers are right there. More tin inidians and more zinc in wheats and NO tin in memorials(1963 to 83). Information from the Red book.

 

[Electricfrontporch]

The difference maybe due to different foundry techniques rather than the advertised alloy mixture.
Maybe the difference in density of the actual slug used at the mints?
I'm sure a lot changed in the process through those years.
Food for thought.

Noah

 

[cudamark]

Did you read my response? The answers are right there. More tin inidians and more zinc in wheats and NO tin in memorials(1963 to 83). Information from the Red book.

Except that the '44-58 Wheats don't have any tin either, but, still read different. To add another wrinkle in the discussion.....the '44-46 wheats are made from used shell casings, not virgin copper/zinc sheets.

 

[Iron Buzz]

Did you read my response? The answers are right there. More tin inidians and more zinc in wheats and NO tin in memorials(1963 to 83). Information from the Red book.

I read "Now here is the tricky part. It's the amount of that .050 tin/zinc ratio that affects the phase. I would say in indians, there is more tin than zinc and in wheats, there is more zinc than tin. Also, from 1959-1962 the composition of this memorial coin was the same as wheats and on my CTX they read like them."

Bolding is mine. You gave an opinion. This time you are giving facts, and especially, the source of those facts. Thank you. I like sourced facts.

 

[Tom_in_CA]

1864 - 1909 Indian Head Penny : 95% copper, 5% zinc, 3.11 grams
1909 - 1982 Copper Lincoln Cent : 95% copper, 5% zinc, 3.11 grams
1982 - 2014 Zinc Lincoln Cent: 97.5% zinc, 2.5% copper, 2.5 grams

So... why do those Indian Heads ring up with the same ID as a zinc penny? On my XP Deus at 18K, a copper Linc reads 90-91. An Indian Head and a Zincoln both read 85-87. Why?

I haven't read through all the other replies, but I think I know what you are trying to ask, and I think I have the answer:

Looking at the metallic compound recap you give, wheat pennies and IH pennies SHOULD have the same TID, right ? But they don't. And to FURTHER confuse the matter: There are year-spans of wheat pennies that ALSO read differently than each other. Eg.: the teens read different than the 1940s/50s wheaties. DESPITE the exact same supposed makeup. And EVEN when testing never-before-buried coins (like if you pulled them out of a coin store, and not md'ing related finds).

Here's the explanation I've heard: That copper varies in trace mineral contained in it. So therefore a copper mine in Utah, has subtle differences in their copper than copper mined in Montana, for instance. And as the years and decades progress, Uncle Sam buys the bulk metal on the open market. From wherever the current production is going on . And that moves around depending on the spot-market of selling price for whomever/wherever is being mined.

Same for gold: Notice that "Rose" gold is a slightly different color than regular gold. Yet both are simply "gold" right ? The color difference is because rose gold is mined in one location, versus regular gold mined in other locations. The trace elements cause the color difference. And so too do the trace mineral differences skew the TID's on our machines.

This is the way I've heard it explained anyhow.

 

[Iron Buzz]

I haven't read through all the other replies, but I think I know what you are trying to ask, and I think I have the answer:

Looking at the metallic compound recap you give, wheat pennies and IH pennies SHOULD have the same TID, right ? But they don't. And to FURTHER confuse the matter: There are year-spans of wheat pennies that ALSO read differently than each other. Eg.: the teens read different than the 1940s/50s wheaties. DESPITE the exact same supposed makeup. And EVEN when testing never-before-buried coins (like if you pulled them out of a coin store, and not md'ing related finds).

Here's the explanation I've heard: That copper varies in trace mineral contained in it. So therefore a copper mine in Utah, has subtle differences in their copper than copper mined in Montana, for instance. And as the years and decades progress, Uncle Sam buys the bulk metal on the open market. From wherever the current production is going on . And that moves around depending on the spot-market of selling price for whomever/wherever is being mined.

Same for gold: Notice that "Rose" gold is a slightly different color than regular gold. Yet both are simply "gold" right ? The color difference is because rose gold is mined in one location, versus regular gold mined in other locations. The trace elements cause the color difference. And so too do the trace mineral differences skew the TID's on our machines.

This is the way I've heard it explained anyhow.

This may not always have been true (most certainly has not!) but one site I found says, "Copper is routinely refined to 99.98% purity (even more pure than Ivory Soap) before it is acceptable for many electrical applications.". But I think that would only be true in the post-electrical part of the industrial age, since I think that sort of purity is only reached by electroplating.