What is an OMM (over mint mark): Educational Series

Posted on by Minterrors
Over mint mark - A 1944 D over S Lincoln Cent. This is the FS-511 variety which has lower population numbers.

A mint error produced by the mint that is working die related

The over mint mark (OMM) series in the Lincoln Cents is special. Two over mint mark error coins occurred in the 1940’s, in close proximity to the 1943 copper cent and the 1944 steel cent. Today we are going to look at the 1944 S over D over mint mark and the 1946 S over D over mint mark.

How is an over mint mark error coin created?

  • Back in the 1940’s, The US Mint used to produce dies in mass.
  • The only thing that was left off of these dies was the mint mark.
  • The Mint workers used to have boxes of dies at their disposal. When a new die was to be put into use, they would take one out of the box and place it in a vice.
  • The mint worker would then put a visor on his head which offered significant magnification.
  • Then, The mint worker would grab a steel rod that had a mint mark on it, a “D” or an “S” at one end.
  • In his other hand he has a mallet.
  • He aligns the mint park punch in an acceptable area on the working die ( anywhere below the date, in the field (flat area) below the date.
  • Once the mint worker is happy with the placement, the takes the mallet and gives the punch a good strike, punching that mint mark into the working die.
  • The mint worker quickly inspects the working die to make sure the mint mark is sufficient enough and the die is ready to go into a mint press and start making coins.

An over mint mark occurred when two different mint mark locations are on top of another. Over mint marks that have occurred on coins that were released to the public include 1944 D over S Lincoln Cent, the 1946 S over D Lincoln Cent, the 1900 O over CC Morgan Dollar. There are a few years in the Buffalo and Jefferson Nickel series that had an over mint mark as well. There are Washington Quarters that have an OMM, and the list goes on. Today we are focusing on the Lincoln Cent over mint marks.

1944 D over S Over Mint Mark

For 1944 D over S, there were two different types of Over mint marks created, one was listed as FS-511 and the other is the FS-512 variety. We’re going to show photos of each 1944 D over S over mint mark.

1944-D/S 1C OMM, FS-511

  • This 1944 D over S OMM, FS-511 variety shows one half of the “S” mintmark to the north of the “D” mint mark.
  • In the photo below, the top portion of the “S” is evident under magnification and good lighting. You can see some of the middle part of the “S” within the top part of the hole of the “D”.
  • This is probably an earlier die state, meaning, when the die struck this particular coin, the die was relatively new.
  • This is a logical guess since we are able to see portions of the middle part of the “S” in the hole of the “D” near the top. If it was a older die state, this area would not be present as die wear would have blended it away.
  • Of the two 1944 D over S over mint mark varieties, this FS-511 variety has lower population numbers.
Over mint mark - A 1944 D over S Lincoln Cent. This is the FS-511 variety which has lower population numbers.
Over mint mark – A 1944 D over S over mint mark (OMM) Lincoln Cent. This is the FS-511 OMM variety which has lower population numbers.

1944-D/S 1C OMM, FS-512

  • This 1944 D over S OMM, FS-511 variety shows a portion of the “S” mintmark to the west of the “D” mint mark.
  • In the photo below, the bottom portion of the “S” which is directly below the “D” is evident under magnification and good lighting.
  • You can see some of the middle part of the “S” in the of the hole of the “D”.
  • This is probably an medium die state, meaning, when the die struck this particular coin, the die was pretty well used.
  • This is a logical guess since as we are able to see only small portions of the middle part of the “S” in the hole of the “D” near the center. Additionally the middle part of the “S” jutting westward is relatively weak, as well as the bottom of the “S” directly below the “D” is almost non-existent.
  • If it was a newer die state, these areas would stronger and more present.
  • Of the two 1944 D over S over mint mark varieties, this FS-512 variety has significantly higher population numbers.
Over mint mark - A 1944 D over S Lincoln Cent. This is the FS-512 variety which has higher population numbers.
Over mint mark – A 1944 D over S Lincoln Cent. This is the FS-512 variety which has higher population numbers.

Not a big fan of over mint mark (OMM) coins?  Take a look at our major mint error coins called Die Caps: Die Cap Major Mint Error Coins (minterrors.org)

Looking for “normal” coins? Please see Shop – US Coins, Silver Bullion and Numismatic products and services – TheCoinStore.org

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