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<p>[QUOTE=&quot;Oldhoopster, post: 2713280, member: 84179&quot;]I&#039;m not a metallurgist either but here is my reasoning. As the melt in the ingot cools, improperly/incompletely mixed regions crystallize with diff compositions in diff regions (I think uneven or incomplete heating could be as just as likely as improper mixing). The flattening and stretching during rolling should distribute some of these grains near the surface since the strip has more surface area than an ingot. If the acid attacks the varying alloys in the grains differently, it would result in different patterns for each compositions.</p><p><br /></p><p>On coins with a homogeneous alloy, I would expect etching within the grains to be similar, since each has the same composition. I think there was a post a few weeks ago where someone showed a cent that was dipped in acid. It showed ridges and ripples as well but not the distinct orientation as seen on this coin.</p><p>I&#039;m comfortable with the logic, but would love to here from someone with a metallurgy background to tell me what I&#039;m missing[/QUOTE]</p><p><br /></p>

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