Quick mint mark question...

More than one person already noted this, but I will add a bit of clarification.
What is an RPM? The mint used to create all of the working dies from a working hub that did not have any mint mark on it. Then, before the die was to be used, a mint employee would use a punch with the mint mark on it to apply the mint mark to the die. Sometimes, the mint mark was punched in the wrong place or possibly not well struck and the mint worker would have to punch it again. The second punch may not be in the exact same place as the first one. It is also possible that the punch would bounce when it was hit and left more than one impression on the die.
This explains how an RPM is created. The two impressions on the die come out as 2 mint marks on the coin. That is also why the placement of the mint mark can vary greatly from coin to coin.
About 1990 the mint started putting the mint mark on the hubs and no longer punching them on the individual dies. Therefore, there can no longer be an RPM.
Here is a picture of a mint worker applying a mint mark to a die.

 

Log in or Sign up to hide this ad.

Well, @Dearborn , since you opened Pandora's box....what about OMMs? Am I assuming correctly, all the die preparation was done at Philly prior to being shipped to respective branch mints and they simply did an oops or changed their minds?

 

The size of the MM isn't necessarily proportional to the size of the coin. The 10c 1905-O Micro O was caused by using the MM from the quarter on a single dime die.

Yes during that era all the die preparation was done in Philly. It was tightly controlled and the branch mints had to ship all their used or previous year dies back to Philly. I can't remember what year Denver started making their own dies but it's on Wexlers somewhere.

 

It really depends on what time period you are talking about.