Something that happens during the minting process of striking the coin. I can't remember the terminology at the moment.
NOTE to long-time professional numismatists and well-informed collectors on CT: Please, let's resolve this year NOT to over-explain , cook up wacky theories, invent possible outcomes, etc. to explain DAMAGE, LINT, DIRT...and more that we see or DON'T SEE.
I don't see any significant damage on the O, beyond normal circulation dings and wear. Remember, we're looking at an image where that letter O is blown up (on my 15" laptop screen) to the size of a half dollar itself. How does the corresponding spot on the obverse look? Anything that could damage the mint mark to that extent is likely to have left a signature on the opposite side as well.
Excellent point ...the opposite side of a counter stamped, chopped, or SEVERELY damaged coin will often show this effect (smushed out design or field *). However, in the case of minor, "micro damage" that will not be the case. If the "smush" was on anything BESIDES the "S" on this coin, no one would care or even see it. Also, as you point out, the "damage" on the "O" is not significant. In fact, no one should consider it other than normal wear and tear. Furthermore, I'll bet my posting privilege on CT : but only for the rest of the day ) that the other side of the OP's coin is normal! Problem I often see (REMEMBER - all posts are MY OPINION) on CT is everything gets exaggerated. Posters wish to call "everything" cleaned or PMD. Coins get wear and tear as they circulate... the more circulation they receive, the less SOME hairlines, cuts, scratches, rim hits, damage matters. *I've posted micrographs of both sides of a very small "punch mark" that flattened the reverse very little.
Well, first off, thanks for the compliment insider. But when it comes to threads like this, especially with such tightly cropped photo of one area, the best we can do is guess. And my guess is an educated one from what is presented mixed with experience. There are really only 3 basic things that could have happened to the mm here. Either both mm posts on the die broke off then circulation smoothed it down to a "blob" OR the mm took a few major ding hits that pushed the raised metal around then circulation smoothed it down to a "blob". As well as a third option of a heavily worn out mm punch being used. These are not cooked up wacky theories. They are educated guesses which, with the evidence presented, is all we can do. Now, as for being a vlds die, look at the denticles. And being a vlds coin, this plays to the first theory of broken posts or of an overused mm punch over localized hits that pushed the metal... And remember, what you don't see can actually be just as important as what you do see in some cases
I'm really trying here To further our education, would you be able to post photos to support your "educated guesses/" 1. A mint mark with broken posts. Never mind, I HAVE seen "D" mintmarks with one serif (post? in your example) filled in (so it appears not there - broken?). Unfortunately, they look NOTHING like the OP's coin. 2. Bingo. 100% correct. The ONLY (non-wacky IMO) explanation for an "S" that looks like the OP's coin. Props to cpm9ball ! 3. A worn MM punch: Never mind, I've seen these also and they NEVER look like the OP's coin. Guess I don't need to see any photographic proof from you; BUT I will be on the lookout for examples of #1 and #3 to post as an educational exercise sometime in the future.
Is it S or is it O. Aye, that is the question. Is there a line in the middle or is there not? Mayhaps a view from one side or the other might glimpse an end to the S or a rise in the middle connecting the arcs of the S. As I stare at that wretched blob such a ghostly line doth appear.