I'm pretty astute on many elements of Large Cents, but this one has me scratching my head. http://coins.shop.ebay.com/i.html?_...kw=&_osacat=11945&_trksid=p3286.c0.m270.l1313 It is a variety S-221 R2 so not rare as a variety. It is said to be incused on the obverse, but I can't figure out how. A brockage is incused, but has a reverse image. It happens when a previously struck coin fails to clear the coining chamber and the new planchet recieves a strike from the previous coin rather than the die causing the incusion and reversed image (not to be confused with an image of the Reverse). This coin has a normal orientation and yet incused. I just can't figure this one out. Any ideas would be appreciated. ps The reverse is normal.
Sorry about that. http://cgi.ebay.com/1801-Large-Cent-ERROR-Incused-Strike-Obverse-L-K-/250762576200?pt=Coins_US_Individual&hash=item3a629d4148 Could it be a counter brockage rather than incused? A coin struck BY a brockage rather than a die or properly struck coin?
Your right, the letters/date would be in reverse going counter clockwise. I think this might be a dug coin, the acidic soil attacked the raise area of the date letters eating into the coin creating this look. I can't be 100% sure about any of what I just said, it's one of those conundrums, but is not what the seller is describing.
BR549 has the answer, it is the result of exposure to some kind of weak acid environment. In this case it has attacked the relief areas of the design more strongly that the fields. My 1798 S-152 has the entire reverse like this coin.