Luster question

So two friends and I have been in an on going argument whether or not a coin can be dug up from the ground with luster still remaining (in soil, keep in mind the rain washing down the soil on top of it) since we metal detect. What are your personal opinions on this (I will not give away our opinions and explanations yet so none are swayed a certain way). Also we are assuming it's a silver coin so factor in the length of how long it's been buried.
Thank y'all for looking,
SCDigginWithAK

 

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I'm not a metals expert, but I fathom it's unlikely to keep its original luster. That probably doesn't mean it's impossible. I guess it depends on what actually comes into contact with the surface of the coin and whether that can be removed without damage.

 

I think it will greatly depend on what the coin is made of and how long its in the ground.

 

I'd vote Yes/No because you didn't provide any other options.

Chris

 

Do you know what makes lustre? here are photo micrographs of the surface of a MS Peace dollar surface with lustre at approx. 350x and 800X. Notice the vertical ridges that act as reflector surfaces to produce a 'wagonwheel' effect as you rotate the coin. This is also what produces toning when thin layers of chemicals overlay the reflective surface. Any solution of chemicals or mechanical wear that reduces these tiny vertical protrusions will remove lustre and produce a flattened area on the surface, So it is the amount of such attenuation that reduces luster. Yes/no is a good answer....but almost always towards the negative effect.

 

Do you have a micrograph of a low grade coin?

 

No silver coin could have any luster left if in the ground for 50+ years. IMHO.

 

That is most likely the case. However, maybe it gets "encased" by something that doesn't damage the coin and may even prevent damage from outside substances. Maybe similar to the movie Jurassic Park. The dinosaurs DNA was found in hardened amber and stayed preserved for millions of years.

 

Maybe we should have the motion picture industry make our coinage. I'm sure they could probably come up with better alternatives to dead presidents.

Chris

 

Jim has provided a good example showing how luster occurs. These ridges are produced along the surface of the coins as the metal flows outward toward the rim.

Being buried in the ground would remove these ridges due to water and soil materials flowing over the surface.

Chris

 

I do, however we wanted to have a nice claim and "scientific" explanation, which you provided. Thank y'all for commenting and voting.

 

Next time I have that scope setup, I will take some photos of a low grade coin.

 

Great! That would be interesting to see the difference.

 

Shouldn't this picture give us our answer?

 

Yes, to a certain extent. The coins at the top of each stack were probably exposed to the greatest wear (slowly!) over time. The fact that the coins were in containers probably slowed that action.

Chris

 

I voted "Yes" because I believe it is POSSIBLE for a coin to retain its luster while in the ground, but only under certain conditions.

Is it probable? I think no.

 

You didn't mention what kind of coin!! I voted yes cause gold coins likely would copper not a chance silver possibly dependent it the environment. A hot dry climate like a desert it could would likely be toned yet still have luster

 

Depends on how long they're in. After a month, year, sure it will still have luster. Eventually it will go away though

 

In my original post i stated "assuming silver". Thanks for your reply