S Over D Mint Mark? ?

Looks like the D took a few hits while in circulation, so post-mint damage.

It would be practically impossible for such an over-date to occur, as the San Francisco mint only produced proof cents in 1979, with the S mint-mark. The Denver mint produced only circulation strikes during this year, with a D mint-mark.

A proof die is very different from a circulation strike die; the proof one has polished fields, to give it that "mirror" look, whereas the business strike one does not.

The only way this over-date would be possible is if a circulation die from Denver found its way to San Francisco and the mint-mark was re-punched as an S. However, mint workers pay more attention with proofs than they do on circulation strikes, so they would have noticed they had the wrong die type and wouldn't have re-punched the mint-mark at all.

You are correct that this is just a PMD mintmark, but the way a D or S or S over D would occur would NOT be at the Denver or San Francisco mint. The error would have happened at Philadelphia. At that time ALL of the dies were made at Philadelphia and that was where the mintmarks were punched into the dies (Since 1997 Denver makes its own dies, San Francisco dies are still made in Philadelphia). The mintmarks were punched in before the proof dies were polished so the proof dies and the dies intended for business strikes in Denver would have looked the same. That is how the 98,99,and 00 WAM cents and the 98 S and 99 S CAM cents happened. Dies intended for proofs were accidently used in Philadelphia to make business strikes and business strike dies were accidentally polished and sent to San Francisco where they were used to make proofs.



Doubtful, just looks like PMD.