Trying to figure this one out and would like some expert opinions.
At first glance, I thought it was PMD
caused by someone scratching or gouging the coin, but on closer inspection the lines are too fine and too even in depth for this to have been done by hand.
All of the lines appear to radiate from the center of the coin, or at least cross through the center, but not from a center point. Most of them come from the area of Lincolns neck just above his collar and under the ear, but a few (not many) miss that and go above, below or to either side.
The lines are definitely incuse and not stains and some of them go up to the rim while other look like the cross it, but not with as much depth as on the fields. Also, many of the lines appear to stop right before the rim.
Plus, it's both the obverse and reverse with a similar pattern (looks identical, but can't say for sure).
I don't see any crossing lines that would indicate a woven fabric type material was involved, and the incuse nature of the lines suggests no acid or etching chemical was involved.
Thanks for your time,