Here is a penny I got back in change a year or so ago. Just wonder what caused it. The coin is missing alot of letters and detail. Thanks, Ben
Just a guess - but I'd say somebody placed a few drops of acid on the obverse. The reverse appears to have normal wear.
Might be what is known as a "strike through" type error, where there was grease on the obverse die, obscuring the details when the planchet was struck.
Definitely a "grease strike". The coin was struck through a layer of gunk that clogged the recesses of the die. These sorts of errors are also called "filled die errors" and "strike-through errors".
