Excuse my ignorance, I am at a loss here. I always thought that hand punched mint marks ended circa 1987/88. At least for the US cents. Were nickels hand punched at the Denver mint as late as 1997? Below is what appears to be to me a RPM, as none of the other elements, device, legends, etc appear doubled in any way. Just this "D". How was it created? Jefferson nickel, 1997 D: Thank you.
Ah ha, according to D. W. Lange (The Complete Guide to Lincoln Cents) the hand punching of mm's ended in 1989 for the cent, with the other denominations following suit in 1991. So, again, I cannot explain the above mm for this 1997 coin.
If machine doubling, why only the "D"? Would not other elements be affected, even slightly? I would prefer to suspect that a die was made with this doubled mint mark, and that a limited number of coins struck with it. Come on, does ANYBODY have a reasonable opinion? MD is the best guess so far, and perhaps the die issue.
Agreed it is strike doubling, in this case it affected the deepest part of the die, which in this case was the deeply punched mintmark - per Fivaz and Stanton (Cherrypickers' Guide, 5th, vol. 1). Thank you Chris and Ken for helping me to see this. Case closed. (see I'm not just an old useless hillbilly, I can still learn!!
Machine doubling can happen this way. All it takes is for the coin and die to hit each other in some odd way and you get machine doubling. Perhaps the mint mark (on the struck coin) got hung up on the die during ejection. The "deeply punched mint mark" only applies to coins made from dies that had hand-punched mint marks.
You are making my brain hurt. Yes that makes sense. Probably better than suspecting that an actual die had this double D imperfection.
