A bronze lookin error 20p from the same period the mint started applying a copper coating on steel cores 1 and 2 pence coins this coin however is not magnetic so it has only been coated over a normal cupronickel 20p
This looks like a regular cupronickel 20p which got discoloured by being in a hostile climate for too long, e.g. in the ground, in a ditch or in the sewers.
Impossible, cupronickel coins can tone but dont turn into a smoot bronze surface like that. Cupronickel is an alloy of copper and nickel, while bronze is a distinct alloy of copper and tin. A hostile environment cannot change the fundamental metallic composition of a coin to transform it into a different alloy.
A cupronickel coin can certainly look like it has turned bronze due to chemical reactions on its surface., caused by the copper in the alloy reacting with environmental factors. If buried the coin will have vivid green, fuzzy corrosion that pits the surface. Unlike attractive toning, this is irreversible and can destroy the coin. Since this coin dosnt show any of that i would say you are 100% wrong
I know little about metallurgy, but during my collecting carreer, I've come about at least 4 discoloured copper nickel coins. I don't like them, so after getting a decent one, I simply give away the discoloured one for free. In your case, I would spend the 20p. Discoloured copper nickel coins are not rare.
That's just environmental damage. Denickelification happens easily in salty or acidic conditions, which is why CuNi coins found in the ground or water, or if improperly cleaned, will have this problem almost all the time. The coin does not have to show obvious signs of corrosion. I believe even few nanometers is enough for copper-spots to appear. Although I am not sure where you see “smooth bronze surface” there. It looks corroded even from those pictures
Edit: CuNi also can have dark patina. Earlier in this message I was referring to the corrosion spots. Though denickelification certainly could have contributed to it having a more “coppery” look
The introduction of copper plated steel for 1p and 2p was already in 1992. Moreover the planchets of those coins and the 20p have different sizes and even a different shape. There is no relation between the use of copper plated planchets and the odd colour of your 20p from 2011.
Discolouration of copper nickel coins can go from yellowish to chocolate brown. Very dark ones are not common, but they happen and are nothing to be exited about.
I dont think so, it sounds like the usual denier jargon!!! If the coin was subjected to environmental damage or present in a harsh acidic environment it should show some pitting and this coin dosnt so jargon i would say
You all realise that Cupronickel is usually at least 75% copper and 25% nickel, so discoloured coins can happen. American coins are worse, they are 11/12 copper and just 1/12 Nickel clad.
The 20p in question does not look that bronzed, possibly just more than 75% copper. Or more likely discoloured from being in a ditch or dirt for a few years. The fact the OP is delusional and claiming their coin is some type of super rare treasure is hilarious. Its common junk and I would not accept it as who knows where it has been.
We are talking about very cheap muck metal coins here, I would spend it as in my opinion that coin is worth 18 - 19p. They mint them in the 10s to 100s of millions and are as common as dirt.
I love coins. Especially silver, gold and anything really old.
Member of the Royal Numismatic Society of New Zealand and the Auckland Numismatic Society
American coins are worse, they are 11/12 copper and just 1/12 Nickel clad.
That is a very misleading statement. All the modern US Cu-Ni alloy coins are 75Cu/25Ni. You are confusing Cu-Ni clad Cu coins with the actual C-Ni alloy composition.
N#53 - for dime says 8.33% nickel and 91.67% Copper that is 1/12 and 11/12 if you do the maths. This is a coin which has an extremely high amount of copper in it, despite it being a “silver/white” coloured coin.
N#6918 - Clad Kennedy halves say the actual percentages as well
N#44 - Jefferson nickels have the most actual “nickel” in them, a whole 25% and the rest again, more of that near worthless copper.
So you owe me an apology, these are nickel plated copper, not copper nickel coins. The modern US series is amongst the most coppery of the “Cupro nickel coins”. Most commonwealth Cupronickel has 3 x as much nickel or 25%.
I love coins. Especially silver, gold and anything really old.
Member of the Royal Numismatic Society of New Zealand and the Auckland Numismatic Society
These guys are arguing over metal composition of coins but are positive about my coin!!!!! Mr scientists if it was in some ditch it would have a uniform shade and discolouration so I suggest you go and learn you keyboard scientists
These guys are arguing over metal composition of coins but are positive about my coin!!!!! Mr scientists if it was in some ditch it would have a uniform shade and discolouration so I suggest you go and learn you keyboard scientists
And I suggest you get some manners when grown folks are talking. Seriously you showed a junky coin that is discoloured through post mint damage. Its not an error, it's a common coin in damaged condition.
Please all of us, lets move on. I would rather fight about precious silver and gold, not stained 20p coins or how much nickel is in a clad American coin.
I love coins. Especially silver, gold and anything really old.
Member of the Royal Numismatic Society of New Zealand and the Auckland Numismatic Society
Really - N#55 - Copper nickel clad copper and you see on the edge its brown in the rim with very light nickel plating on the edges.
No, sorry. The copper-nickel alloy in all those coins is 75% copper/25%nickel. The copper-nickel alloy is clad onto pure copper. To imply the copper-nickel in these coins is “11/12 copper and just 1/12 Nickel” is just wrong. Obviously the properties of the alloy you're claiming it to be are vastly different than the alloy it really is, especially the reaction to environmental conditions, the very reason for this post. I owe you nothing. To help you understand I made this which is a cross section through a US quarter:
Edit: As far as the edge picture you referred to, you need to understand how blanks are made. It's essentially a shearing operation where the soft copper center is dragged over the bottom portion of the Cu-Ni cladding. It is not representative of the actual coin construction.
Really - N#55 - Copper nickel clad copper and you see on the edge its brown in the rim with very light nickel plating on the edges.
No, sorry. The copper-nickel alloy in all those coins is 75% copper/25%nickel. The copper-nickel alloy is clad onto pure copper. To imply the copper-nickel in these coins is “11/12 copper and just 1/12 Nickel” is just wrong. Obviously the properties of the alloy you're claiming it to be are vastly different than the alloy it really is, especially the reaction to environmental conditions, the very reason for this post. I owe you nothing. To help you understand I made this which is a cross section through a US quarter:
Edit: As far as the edge picture you referred to, you need to understand how blanks are made. It's essentially a shearing operation where the soft copper center is dragged over the bottom portion of the Cu-Ni cladding. It is not representative of the actual coin construction.
This version of copper-nickel is very American. It practically doesn't exist outside of the USA. Copper-nickel usually means a mixture of metals, not a clad sandwich composition. The British 20p is not clad. OP has a coin with nasty environmental damage.
Really - N#55 - Copper nickel clad copper and you see on the edge its brown in the rim with very light nickel plating on the edges.
No, sorry. The copper-nickel alloy in all those coins is 75% copper/25%nickel. The copper-nickel alloy is clad onto pure copper. To imply the copper-nickel in these coins is “11/12 copper and just 1/12 Nickel” is just wrong. Obviously the properties of the alloy you're claiming it to be are vastly different than the alloy it really is, especially the reaction to environmental conditions, the very reason for this post. I owe you nothing. To help you understand I made this which is a cross section through a US quarter:
Edit: As far as the edge picture you referred to, you need to understand how blanks are made. It's essentially a shearing operation where the soft copper center is dragged over the bottom portion of the Cu-Ni cladding. It is not representative of the actual coin construction.
This version of copper-nickel is very American. It practically doesn't exist outside of the USA. Copper-nickel usually means a mixture of metals, not a clad sandwich composition. The British 20p is not clad. OP has a coin with nasty environmental damage.
I'm not sure what this has to do with my comment correcting Moneytane's incorrect statement that the Cu-Ni alloy in US coins is 91.7% Cu and 8.3% Ni. That's like saying the composition of a 1 Euro coin is 56% Cu, 34% Ni, 10% Zn where obviously none of the three components have that composition.
