I think this cent has a die chip in the b on liberty and a chip above the I in the word in. My question is about the mint mark is this a d over d or just damage?I originally thought damage but I noticed the d don't look damaged and it kinda looks like a line in the d for a different d. Thank you for looking. Can't wait to hear what you guys say. I'm confused on this one.
By why did zinc rot set in? Because the plating on that area was split. When a split happens, then the zinc is exposed. Then the oxygen reacts with the zinc and makes the area swell: So the area is affected. E&V had the correct answer, I just added a bit to help you to visualize what caused the issue.