1970 Lincoln Cent RPM, Reverse Error

Cannot see the MM in the photo to well. The reverse shows a weak die (common) before it fails.

Is that a bubble on the MM? Try poking it with a tooth pick to see if it is soft.

Reverse is what we call a " Greaser"...the devices on the die were filled with grease and did not allow for a full striking

LIBERTY looks to be bold, not mushy, so further confirmation of the more common large date variety.

I'll let others comment on the rpm question. There could be something under the S, but it could be just glare as well.

Should you keep it? I live in Ohio where most of us keep all S mintmarks since they aren't real common. When the question of "should I keep it" arises, I like to quote fellow CCF member coop when he wrote, "keep what you would buy." Is it worth a couple of cents to you? Only you can answer that one. If not, throw it back. Good luck.

And I almost forgot,
to the CCF!