What coin is this??

[kjob72]

Hi i'm new on here so i apologise in advance if my etiquette is not up to scratch.
I found this coin yesterday, no idea what it is. i found it roughly 5 inches down in very wet soil (now there's a novelty) at first i thought it was another old penny but after a slight clean it appears it may be something else? i've sat it on top of a 1919 penny in the one photo to give an idea of size.  i'd really appreciate any help/suggestions. thanks. kev.

[david995]

Anything to be seen on the reverse ?

[kjob72]

Not a great deal at all unfortunately David995.

[Chef Geoff]

I'm afraid your first suspicions were right in that it's a penny of George V....

[kjob72]

Well thank you for clearing that up. i honestly began to think it was something a bit more exciting by the appearance of it.

[kjob72]

I'm still very new to all this but thanks again for your help. Would you have any idea how it cane to be in that condition? Has it been heated?

[Chef Geoff]

Power harrows are the usual culprits they can cut a coin clean in half if they catch it right but usually just chew it up a bit

[probono]

I'd have thought the particular geology and land use would have caused the problems you see - I find that where I detect different fields have different uses (and underlying rocks) and so the coins that come out of them can vary quite a lot - although brass 3d always come out shot to pieces.

It seems to me that the introduction of nickel in any form to coinage makes it rot much worse than pure copper.

It is also interesting to see how the various silver alloys that were in use between 1920 and 1945 come out of the ground - the earlier ones tend (at least in my experience) to be far worse than the later ones.

[Greg]

If you have a coin made of two or more metals or even another dissimilar metal near by, add some acid rain and you have created small batteries that will erode the coin over time.

[kjob72]

Hmm it's all food for thought. Thank you all for your input, it's all greatly appreciated.

[probono]

If you have a coin made of two or more metals or even another dissimilar metal near by, add some acid rain and you have created small batteries that will erode the coin over time.

Well, it's not quite as simple as that - copper and silver have very similar potentials, so it has to be sufficient I suppose (such as zinc and copper - this last gives a PD of ~1.1V) - and of course you need an electrolyte (not necessarily acid rain - anything that has a salt in solution) - but I've found that the ground conditions also have a large effect - dark soils (at least here) seem to be more gentle to coppers than 'subsoil'. Today I've dug quite a number of old pennies out of a park and many are surprisingly solid (although for  some, when touching, the 'touching faces' were un-corroded).

[Greg]

I think, too much detail for the layman.
It was an attempt to simplify what had happened to his coin.
Metals not so significant, can be done with two types of lead. You are correct acid or alkali.
1.1 volts DC is the voltage required to overcome the internal resistance of a battery when charging, we are not charging, we are discharging mV and micro amps over tens of years.
The lemon experiment in schools produces 0.7 to 0.9 volts.
Head hurts time for bed.