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1976 no mint penny

10 posts in this topic

Hi, can some one please tel me why is the difference in colors for this 1976 penny, I have kept some of them , but not seen this redish color, is it oxidation or an external substance that causes it, it doesnt look damage. Appreciate your comments




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Different forms of exposure cause different forms of tarnish. For example, if you took two identical coins, set one on sulfured paper and another on a bed of dry soil, you'd probably expect different coloring if you left them long enough.

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On 1/27/2022 at 10:34 AM, Vero86 said:

I thought soil corroded  the coin structure did not think about this tanishing was caused by it. Thanks

It would depend on the soil and length of time. For example, the coin that started me collecting was a worn, blackened Barber dime outside my grandparents' ranch house in Kansas. I'm neither enough of a chemist nor enough of a soil analyst to say how that blackening would differ from, say, the soil in my back yard here in Oregon, but I do know that my lodgepole pines need and create acidic soil, whereas most of Kansas is pulverized limestone (I don't think lodgepoles would even sprout) mixed with organic matter from many millennia of grasses. It would seem reasonable that two identical coins, dropped in those two locations and left for sixty years or so, might acquire different coloring.

Cu is pretty reactive and can form a lot of compounds that have different colors. Of course, corrosion can also pit a coin and eventually eat it away. When they find old copper hoards in Europe from Roman times, the first job is to break apart the huge coin clod into which they have connected due to dirt and corrosion. (In that case, I think electrolysis is the preferred method, but I've never done it.)

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