RPM stands for a Re-Punched Mintmark.
MM stands for Mintmark (aka, Mint-mark).
RPMs are related to re-punched dates (RPDs).
RPMs are a type of die error that is considered a VARIETY
RPMs are often designated as being a D over D, or S over S, in shorthand it would appear as:
D/D
S/S
D/D/D (for a triple punched RPM)
RPMs are found on coins during certain years when punches were used.
To distinguish coins minted at branch mints from one another (except Philadelphia) branch mints had the first initial of the city punched into the die face by hand until 1989. Being this was done by hand, mishaps occurred - these mistakes are called RPMs. CONECA catalogs and attributes RPMs.
- Carson City (NV) CC 1870-1893
- Charlotte (NC) C 1838-1861
- Dahlonega (GA) D 1838-1861
- Denver (CO) D 1906-1989
- New Orleans (LA) O 1838-1861, 1879-1909
- Philadelphia (PA) P (1942-45 with nickels), 1979-1989 (except Lincoln cents)
- San Francisco (CA) S 1854-1955, 1968-1985
- West Point (NY) W 1984-Present
- Mint marks were placed on the reverse of coins until 1968 when they moved to the obverse
- No mint marks appeared on circulating coins from 1965 to 1967
- Note: the US Mint no longer punches the MM into the die face
Or in other words from the clearest deepest MM to the lightest weakest MM.
Alan Herbert apparently designed this order to be opposite that of doubled dies.
We are using the following directional terms as per the chart below:
NW: northwest
N: north
E: east
NE: northeast
SW: southwest
W: west
S: south
SE: southeast
Pivoted (which is sometimes called tilted)
Rotated (which can be directional)
CW: clockwise
CCW: counter-clockwise
Horizontal
Inverted
MM-OVERLAY-CHART copy.jpg
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