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<p>[QUOTE=&quot;Oldhoopster, post: 4631330, member: 84179&quot;][USER=24314]@Insider[/USER] I&#039;ve always enjoyed your columns in the numismatic publications and learned a lot from them over the years, but I disagree with your conclusions on this coin.&nbsp; From a materials science and metallurgical standpoint, it doesn&#039;t make sense for the discoloration to be so uniform if it was caused by inhomogeneities in the melt. I would expect any poorly melted/mixed area to be random in size and shape.&nbsp; While the rolling process elongates these grains/domains, the thickness should vary due to the original shape of the poorly mixed region.&nbsp; Think of the old silly putty ads.&nbsp; When you transferred an image from a comic and stretched it, did it deform at a consistent size and shape across the entire piece?</p><p><br /></p><p>IMO, I believe that the mint was doing something in the early 80s with the rolling process. The lines in the OPs cent look like stains, not a composition variation. Process Engineers are always looking for ways to make things &quot;better, faster, cheaper&quot; (I&#039;ve spent a chunk of my career as a process engineer).&nbsp; I suspect that they made a process change that somehow resulted in oils/lubrication being pressed into the surface as the ingot was rolled.&nbsp; It may have taken a little time for this to discolor, but once it was noticed, the process was changed.&nbsp; This would explain the [USER=1859]@mikediamond[/USER] comment about seeing this discoloration on cents from this time period.&nbsp; I can also add anecdotal information about seeing these thin, even stripes on cents from the 1980-81.&nbsp; If oils are forced slightly below the surface during the pressures from the rolling process, I would expect stains from environmental exposure, not laminations.</p><p><br /></p><p>I hope this answers some of the questions you posted in previously.&nbsp; I&#039;m not 100% convinced that roller marks are the explanation, but it makes a lot more sense than improper alloying (at least to me)[/QUOTE]</p><p><br /></p>

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