1970 S. It Looks Like The The S Is Too Close To The 9 And Rusty

The mintmarks were added to the dies until 1990 when they are since then, part of the design. The mints not create there own dies on location. On the mintmarks pre 1989, they were added to the die with a mintmark punch. There target area for the mintmark was not on the digits, inside the bust to rim area and below the date. So you see them very close or very far from the date. They were added by hand to the dies with a mintmark punch:

So the mintmarks will vary in location. Some of the mintmarks were in the digits and they were relocated to the correct area:

These are RPMs.

Note how many times they changed the mintmark location until it was at the acceptable level. Some are angled:

So are far away:

They landed pretty much where they landed. All done by hand for locations. I prefer the mintmarks added by hand, as it makes identifying attributions easier to determine.

Certainly close, but I don't think that it is touching the number 9. A close-up of this area might help to confirm as this is the best that I can do with the current pics.

Yes, good ol' hand-placed mint marks. Location will vary. The 'rustiness' appears to be the result of prolonged exposure to somewhat harsh environmental agents.