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What environmental issues causes this color.
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<p>[QUOTE="John Burgess, post: 4960574, member: 105098"]the natural oxides for copper.</p><p>Copper(I) oxide -red (4 Cu + O2 → 2 Cu2O)</p><p>Copper(II) oxide - black (2 Cu + O2 → 2 CuO) (heating copper with oxygen to 300-800 Celsius.</p><p>CuO Cupric Oxide - green/blue...... (CuCO3.Cu(OH)2) or (2CuCO3.Cu(OH)2)</p><p><br /></p><p>there's others of course, that's the main 3 that are the least complicated and replicate even on accident or naturally, this is how ceramics were colored in the glaze in the old days by using various copper oxide powders in the ceramic mix to color it.</p><p><br /></p><p>So, it could be hypothesized that a red oxidized "patina" was due to oxidization without the presence of sulfur but in a wet environment that is acidic, and likely also chlorinated to some extent, not simply freshwater with a neutral pH. a "pond penny" or "fountain coin" most likely.</p><p><br /></p><p>A black oxidized "patina" cent would be hypothesized to have been exposed to high temps above 300 Celsius but below melting with a respectable introduction of oxygen (air). a household wood fire, fireplace or wood stove burns at about 600 Celsius, wood is combustible at 300 degrees Celsius, as an aside. normally boiling water, 100 degrees Celsius just to give an idea of where conditions have to fall as far as temperature and then oxygen.</p><p><br /></p><p>Green oxidized cent would be hypothesized to be exposure to sulfur and oxygen and water. Even atmospheric sulfur from cars and factories, pretty much why the statue of liberty is the color it is.</p><p><br /></p><p>Coppers red oxide is the likely culprit here, and in my opinion, coins that look like this spent time in a chlorinated fountain under the right conditions with chlorine as the likely oxidizer.</p><p><br /></p><p>I am also certain someone that knows a heck of a lot more about science, elements and minerals, and formulas than I do, may declare shenanigans on this post and what I've written, I am not 100% clear that I understand it all.[/QUOTE]</p><p><br /></p>
[QUOTE="John Burgess, post: 4960574, member: 105098"]the natural oxides for copper. Copper(I) oxide -red (4 Cu + O2 → 2 Cu2O) Copper(II) oxide - black (2 Cu + O2 → 2 CuO) (heating copper with oxygen to 300-800 Celsius. CuO Cupric Oxide - green/blue...... (CuCO3.Cu(OH)2) or (2CuCO3.Cu(OH)2) there's others of course, that's the main 3 that are the least complicated and replicate even on accident or naturally, this is how ceramics were colored in the glaze in the old days by using various copper oxide powders in the ceramic mix to color it. So, it could be hypothesized that a red oxidized "patina" was due to oxidization without the presence of sulfur but in a wet environment that is acidic, and likely also chlorinated to some extent, not simply freshwater with a neutral pH. a "pond penny" or "fountain coin" most likely. A black oxidized "patina" cent would be hypothesized to have been exposed to high temps above 300 Celsius but below melting with a respectable introduction of oxygen (air). a household wood fire, fireplace or wood stove burns at about 600 Celsius, wood is combustible at 300 degrees Celsius, as an aside. normally boiling water, 100 degrees Celsius just to give an idea of where conditions have to fall as far as temperature and then oxygen. Green oxidized cent would be hypothesized to be exposure to sulfur and oxygen and water. Even atmospheric sulfur from cars and factories, pretty much why the statue of liberty is the color it is. Coppers red oxide is the likely culprit here, and in my opinion, coins that look like this spent time in a chlorinated fountain under the right conditions with chlorine as the likely oxidizer. I am also certain someone that knows a heck of a lot more about science, elements and minerals, and formulas than I do, may declare shenanigans on this post and what I've written, I am not 100% clear that I understand it all.[/QUOTE]
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