Discussion on: Why do some coppers corrode on one side only

[Don in SJ]

On Today's Finds a discussion started concerning Chris's 1794 Large Cent that is great on one side and not so on the other and it sounds like a good discussion item so rather than have it attached to Chris's nice 1794 post I thought a separate post here might work.

Here are some of my early morning thoughts on the subject:

Some reasons for one side good, other side bad: Sitting undisturbed in one position I believe is first and foremost condition for this to happen, but could be wrong, however I do not hunt plowed fields and have quite a few coins from the 1700s with one side great and the other side damaged by corrosion.

My thoughts are, man applied fertilizers, cow/deer/horse, etc urine. Laying in one position in normal acidic soil (Southern NJ soil is naturally highly acidic) that remains wetter than other areas. I am sure there are others, I don't buy the acid rain being a major contributor since it would be more general finding the damaged coins.

Type of soil and drainage is of the utmost importance in determining the condition of coppers in the ground.

Another thought, are we positive it is the top side that gets the corrosion and not the bottom? If you leave a piece of wet metal on top of the ground, of course the top side dries first and the bottom stays wet very long, so a coin buried in ground that does dry out at times, would leave the top drying out more often than the bottom side, just another thought.

Attaching 3 coins found at the same sawmill site in 2007 or so and two of the three have same type of one sided corrosion. Now is it from there position in the ground, since one copper does not have it. The soil was well drained sandy soil, it was not farmed at all unless it was done before the 1790s. The area now is lightly wooded with Oak and Pine trees and minimum underbrush.

These two 1796 Liberty Caps were found within 100 feet of each other, but I do believe the one with the corrosion was found and couple inches deeper (8-10") and on what was once an old wagon road next to the sawmill.


But the KGIII counterfeit was found uphill from the two 1796s, but within 100 feet of the other corroded one and yet it has the same type of one sided corrosion. This was about 5-7 inches down in sandy soil.



Don

 

Amazon Forum Fav 👍

Agony and Death on a Gold Rush Steamer: The Disastrous Sinking of the Side-Wheeler Yankee Blade - Grab it through Amazon!

[jeff of pa]

most likely the bottom side is
protected somewhat.

 

[DGDancer]

Just a guess but depending on what side was "up" when it went under might be the determining factor.
The bottom side may be more shielded to water sitting on top of the coin where as the bottom
stayed relativly dry. Moister on top would probly tend to collect there for longer allowing more
corossion to take place. Also possible that the coin may have been stepped on and the top side
had materials ground into it just enough to let corrosion take effect. A thought....

 

[ivan salis]

just like the roof of a house when it rains --the top of the roof gets wet but the inside (bottom part)does not -- if the coin is in a flat position the "up" side gets wet as the rain goes on top and then drains off going past leaving the "bottom" basically dry ( like the roof of a house does or a carport area)--all the chemicals in the water and soil too will effect the wet top side more so than the dry bottom side -- if the soil is basically well drained soil that is

 

[ppratt]

Very good topic I guess I have to think about it more. But to add to your acidic theory I think your right any copper coin I have found under a pine tree has been nothing more than a slug. Also I just built a house and were the Pines once stood I cant grow grass cuz of the acidic levels.

 

[Iron Patch]

Ah yes, the old days of park hunting. Been quite a while since I've dug one side good, one bad, coppers.