Help needed with very strange coins The Polish 5 groszy 1923

Hello,

As we all know the Polish 5 groszy 1923 was struck for business both in brass and in bronze:
N#4114 (brass)

N#5632 (bronze)

Brass Composition coin weight is 3.5 g, whereas Bronze composition coin weight is 3 g.

Brass generally 66% copper and 34% zinc or typical composition being 70% copper and 30% zinc.

Modern commercial bronze should be 90% copper and 10% zinc. 

I have a bunch of the Polish 5 groszy 1923 coins which weight is neither 3.5 nor 3 g but 3.2 and 3.3 g.

Those coins have a different color denoting different material composition. 

I sent 3 coins to NGC for XRF Elemental Analysis. Here is what I got from them.

First coin below weight 3.2 g with composition Cu 67% and Zn 32%. 

Second coin below weigth 3.3 g with composition Cu 76% and Zn 23%. 

Third coin below weight 3.3 g Cu 92% and Zn 8%. 

First coin might be classic Brass coin except for weight.

Second coin has too high conten of Cu for Brass and too low for Bronze.

Third coin has very high content of Cu 92%. Which looks like actually like Tombac. 

Tombac with high copper content and 5–20% zinc content.

Especially that third coin's composition is close to what is called "Red tombac of Paris": copper 90%, zinc 7.9%.

All 1923 5 groszy coins minted in Warsaw color should be yellow (brass) or bronze. So what are the coins that I have? Any idea?

It looks to me like material composition trial coins. Parchimowicz mentions such trail coins in his book. Can this be it?

dr_ghanj

 

…

Modern commercial bronze should be 90% copper and 10% zinc. 

…

…Would you confuse zinc (Zn) and tin (Sn)?

Frenchlover

dr_ghanj

 

…

Modern commercial bronze should be 90% copper and 10% zinc. 

…

…Would you confuse zinc (Zn) and tin (Sn)?

Have a look on this coin:

https://www.ngccoin.com/certlookup/3928543-011/NGCDetails/

NGC says it is Bronze coin with composition 89%Cu 11%Zn

NGC is just wrong :)

Without tin (Sn) it is no bronze.

dr_ghanj

Hello,

 

All 1923 5 groszy coins minted in Warsaw color should be yellow (brass) or bronze.

Depends on storage conditions and wear. You probably won't distinguish them, if there are no other visual differences.

Two of them are brass. Other two are bronze.

And I did not go into even darker patina.

tokul

dr_ghanj

Hello,

 

All 1923 5 groszy coins minted in Warsaw color should be yellow (brass) or bronze.

Depends on storage conditions and wear. You probably won't distinguish them, if there are no other visual differences.

 

Two of them are brass. Other two are bronze.

 

And I did not go into even darker patina.

And those storage conditions and wear may change coin composition? Like increasing content of Cu and decreasing content of Zn? Especially those coins that I have show gradual steps in increasing in Cu and decreasing Zn. If those coins are the same and have been minted the same time so they experienced similar storage conditions and wear therefore theirs composition should be similar. But I have coins with 92% Cu and 67% Cu. So your explenation does not make sense to me. 

yvon

Without tin (Sn) it is no bronze.

I can agree to that, no tin no bronze, but that's not the point of my post. 

The point was that you can't distinguish between brass and bronze alloys that are impacted by patina and wear. Unless you find catalogue entry telling you which one of those is brass. Both brass and bronze can be "yellow" unless you start puling pantone palette and colorimeters to recognize colors

If you do not melt your coins and separate all the metals, you can't say that your coins got x % of copper. You know copper percentage only cause some reference book told you so.

dr_ghanj

I can agree to that, no tin no bronze, but that's not the point of my post. 

So you might precise the purpose of your post.

Frenchlover

dr_ghanj

I can agree to that, no tin no bronze, but that's not the point of my post. 

So you might precise the purpose of your post.

Point of my post is quite precise and is stated at the very bottom of my post -→ It looks to me like material composition trial coins. Parchimowicz mentions such trail coins in his book. Can this be it?

I think it's obvious what the point of this post is (and the other 3 posts about the same coins with no firm conclusions):

Stated very simply:

1. Three coins of two possible compositions.

2. One coin is Cu 67% and Zn 32%.

3. One coin is Cu 76% and Zn 23%.

4. One coin is Cu 92% and Zn 8%.

How is that possible?

Forget the needless distractions of color differences and small variations in weight and focus on the three widely different compositions.

tokul

The point was that you can't distinguish between brass and bronze alloys that are impacted by patina and wear. Unless you find catalogue entry telling you which one of those is brass. Both brass and bronze can be "yellow" unless you start puling pantone palette and colorimeters to recognize colors

 

If you do not melt your coins and separate all the metals, you can't say that your coins got x % of copper. You know copper percentage only cause some reference book told you so.

My point was, if my coin with Cu 92% is for example this coin from the pic below.  

rsirian1

I think it's obvious what the point of this post is (and the other 3 posts about the same coins with no firm conclusions):

 

Stated very simply:

1. Three coins of two possible compositions.

2. One coin is Cu 67% and Zn 32%.

3. One coin is Cu 76% and Zn 23%.

4. One coin is Cu 92% and Zn 8%.

How is that possible?

 

Forget the needless distractions of color differences and small variations in weight and focus on the three widely different compositions.

 

Exactly that's the point! Thank you rsirian1!

dr_ghanj

rsirian1

I think it's obvious what the point of this post is (and the other 3 posts about the same coins with no firm conclusions):

 

Stated very simply:

1. Three coins of two possible compositions.

2. One coin is Cu 67% and Zn 32%.

3. One coin is Cu 76% and Zn 23%.

4. One coin is Cu 92% and Zn 8%.

How is that possible?

 

Forget the needless distractions of color differences and small variations in weight and focus on the three widely different compositions.

 

Exactly that's the point! Thank you 

OK, so you can remove any reference to Bronze in your question.

Now let's look at the accuracy of the proportions given by XRF for very close elements in the Mendeleiv table: CU (29) and ZN (30) on coins oxidized by time.
Even though XRF is very precise, it can't do miracles..

Especially due to the fact that the XRF accuracy falls off with metals with low atomic weights.

Frenchlover

dr_ghanj

rsirian1

I think it's obvious what the point of this post is (and the other 3 posts about the same coins with no firm conclusions):

 

Stated very simply:

1. Three coins of two possible compositions.

2. One coin is Cu 67% and Zn 32%.

3. One coin is Cu 76% and Zn 23%.

4. One coin is Cu 92% and Zn 8%.

How is that possible?

 

Forget the needless distractions of color differences and small variations in weight and focus on the three widely different compositions.

 

Exactly that's the point! Thank you 

OK, so you can remove any reference to Bronze in your question.

Now let's look at the accuracy of the proportions given by XRF for very close elements in the Mendeleiv table: CU (29) and ZN (30) on coins oxidized by time.
Even though XRF is very precise, it can't do miracles..

So if I understand you correctly coins a) Cu 67% Zn 32% and b) Cu 92% and Zn 8% might be just simply XRF metro issue.

Then how do you explain difference in colors between those coins?

I'm not an expert in XRF accuracy, so I'm not concluding anything, and references to color are deemed inappropriate as previously stated.

Frenchlover

I'm not an expert in XRF accuracy, so I'm not concluding anything, and references to color are deemed inappropriate as previously stated.

I have different opinion about color. I understand issues related to color but nevertheless color might be also indicator that cannot be totally ruled out from the equation.  

dr_ghanj

Frenchlover

I'm not an expert in XRF accuracy, so I'm not concluding anything, and references to color are deemed inappropriate as previously stated.

I have different opinion about color. I understand issues related to color but nevertheless color might be also indicator that cannot be totally ruled out from the equation.  

If you're going to use color as a discriminator you'll need to remove the effects of environmental damage/tarnish/tint/etc. by removing enough surface material to expose unaffected base metal, something you're probably not prepared to do.

rsirian1

dr_ghanj

Frenchlover

I'm not an expert in XRF accuracy, so I'm not concluding anything, and references to color are deemed inappropriate as previously stated.

I have different opinion about color. I understand issues related to color but nevertheless color might be also indicator that cannot be totally ruled out from the equation.  

If you're going to use color as a discriminator you'll need to remove the effects of environmental damage/tarnish/tint/etc. by removing enough surface material to expose unaffected base metal, something you're probably not prepared to do.

understand and agree with you. That's why like I said not as discriminator but more like indicator. 

Color of brass, before oxydation, is depending on copper/zinc percentage.

In brasses, the red of copper is toned to a range of attractive yellow hues by the addition of varying amounts of zinc, ranging from the gold-like colors of the 95% copper/5% zinc (95/5), 90 /10, 85 /15 and 80 /20 alloys (appropriately called "gilding metals") through the more subtle variations in the 70 /, 67 /33 and 64 /36 series of brasses to the stronger yellow color of the 60 /40 alloy, which was formerly known as "yellow metal."  Then adding manganese (which is not present in your XRF analysis) will lead to a bronze-like color.

Frenchlover

Color of brass, before oxydation, is depending on copper/zinc percentage.

In brasses, the red of copper is toned to a range of attractive yellow hues by the addition of varying amounts of zinc, ranging from the gold-like colors of the 95% copper/5% zinc (95/5), 90 /10, 85 /15 and 80 /20 alloys (appropriately called "gilding metals") through the more subtle variations in the 70 /, 67 /33 and 64 /36 series of brasses to the stronger yellow color of the 60 /40 alloy, which was formerly known as "yellow metal."  Then adding manganese (which is not present in your XRF analysis) will lead to a bronze-like color.

When Manganese is added, the alloy is lightly atracted to a magnet.

yvon

Frenchlover

Color of brass, before oxydation, is depending on copper/zinc percentage.

In brasses, the red of copper is toned to a range of attractive yellow hues by the addition of varying amounts of zinc, ranging from the gold-like colors of the 95% copper/5% zinc (95/5), 90 /10, 85 /15 and 80 /20 alloys (appropriately called "gilding metals") through the more subtle variations in the 70 /, 67 /33 and 64 /36 series of brasses to the stronger yellow color of the 60 /40 alloy, which was formerly known as "yellow metal."  Then adding manganese (which is not present in your XRF analysis) will lead to a bronze-like color.

When Manganese is added, the alloy is lightly atracted to a magnet.

no attraction to a magnet. just checked. 

Frenchlover

Color of brass, before oxydation, is depending on copper/zinc percentage.

In brasses, the red of copper is toned to a range of attractive yellow hues by the addition of varying amounts of zinc, ranging from the gold-like colors of the 95% copper/5% zinc (95/5), 90 /10, 85 /15 and 80 /20 alloys (appropriately called "gilding metals") through the more subtle variations in the 70 /, 67 /33 and 64 /36 series of brasses to the stronger yellow color of the 60 /40 alloy, which was formerly known as "yellow metal."  Then adding manganese (which is not present in your XRF analysis) will lead to a bronze-like color.

thank you very much Frenchlover for your detailed analysis. what you wrote brings exactly to my question. Who and why would produce such series of brasses as you described? As I was asking in my post, is it possible that I have trial mint coins? It is confirmed such conins were minted.   

yvon

 

When Manganese is added, the alloy is lightly atracted to a magnet.

Can you provide an example of this?  A reference to support it? I've never heard of an alloy that had magnetic properties that didn't contain some of the ferromagnetic elements.  I'm not talking about diamagnetism but about stationary attraction (no matter how weak) to a magnet.

rsirian1

yvon

 

When Manganese is added, the alloy is lightly atracted to a magnet.

Can you provide an example of this?  A reference to support it? I've never heard of an alloy that had magnetic properties that didn't contain some of the ferromagnetic elements.  I'm not talking about diamagnetism but about stationary attraction (no matter how weak) to a magnet.

I do not know of the use of this alloy in coins, but in propellors from ships it is widely used. It is an alloy with copper, zinc and maganese and maybe others,  the colour is like brass and it is atracted to a magnet, but not strong like steel or iron.

yvon

rsirian1

yvon

 

When Manganese is added, the alloy is lightly atracted to a magnet.

Can you provide an example of this?  A reference to support it? I've never heard of an alloy that had magnetic properties that didn't contain some of the ferromagnetic elements.  I'm not talking about diamagnetism but about stationary attraction (no matter how weak) to a magnet.

I do not know of the use of this alloy in coins, but in propellors from ships it is widely used. It is an alloy with copper, zinc and maganese and maybe others,  the colour is like brass and it is atracted to a magnet, but not strong like steel or iron.

Thanks. I'm still doubtful. Maybe some of the nickel aluminum bronzes like Nibral but I'm not sure about that.

I'm not sure if it is the percentage of Mn in an alloy that influences the ferromagnetic properties of that alloy.

Manganese is one element (as Iron, Cobalt and Nickel)  that have unpaird D shell electrons.
The exchange interaction (the forces that allow the unpaired D shell electrons in each Mn atom to 'communicate' with other nearby atoms) is too strong for manganese to show ferromagnetism but if the atoms are diluted in an alloy of some other material, it becomes right for atoms to talk to each other and have all their spins aligned to form a large moment.

Reference Here

And from the same reference…

While Jim may be right about the manganese being the source of magnetism in your sample, I am pretty sure it is due to the nickel in mine. If what you have is 630 it is probably the nickel as well.

Edit - I just noticed that 630 also contains iron - another suspect for magnetism.

and

Sounds like aluminium nickle bronze, hard and slightly magnetic.  (aluminum nickel bronze → nickel bronze aluminum → Nibral)

I think we're getting off topic.

rsirian1

And from the same reference…

 

While Jim may be right about the manganese being the source of magnetism in your sample, I am pretty sure it is due to the nickel in mine. If what you have is 630 it is probably the nickel as well.

Edit - I just noticed that 630 also contains iron - another suspect for magnetism.

 

and

 

Sounds like aluminium nickle bronze, hard and slightly magnetic.  (aluminum nickel bronze → nickel bronze aluminum → Nibral)

 

I think we're getting off topic.

"I think we're getting off topic". -→ true haha 😄

dr_ghanj

"I think we're getting off topic". -→ true haha 😄

On the contrary, I think we are really on the subject !
Don't forget what happened to the Polish Navy in 1922 with the events of Dantzig! 

And as yvon rightly points out, the alloys for the Navy contain manganese!

In order to seriously study the magnetic property of your coin, you can very simply place it horizontally at a distance of 1.414 times the radius of a plasma ball and a single green ray may then shoot out as Jules Verne showed in 1882.

This effect only appears if the ball and the coin are placed in your freezer at a temperature below -15°C. 

Other complementary experiments can be done by placing the coin in the microwave oven for 15 minutes after having previously stripped it with a blowtorch.