Glossary List M


Welcome to the Lincoln Cent Forum Glossary.
Use the alphabetical links above to navigate to the desired term.
This glossary of terms was written and compiled by Will Brooks with the help of our forum members. A huge thanks to everyone who contributed knowledge, ideas, words, and photos to make this growing educational resource possible. Special thanks to Richard Cooper, aka “Coop” who donated many of the photos.

Machine Damage Doubling: See Machine Doubling.

Machine Doubling (Also Machine Damage Doubling, or Strike Doubling): This occurs when a loose die bounces (push-type machine doubling) after the initial strike and hits the planchet again in a slightly offset position, flattening a portion of an already struck device, creating a “shelf-like” doubling effect that cuts into the normal size of the device. This is often misconstrued as a doubled die by novices, but is common and essentially worthless. Sometimes the die will “slide” rather than bounce, creating a smeared look to the devices. (slide-type machine doubling). Ejection doubling is another form of machine doubling where the coin “sticks” to the anvil die when being ejected from the striking chamber. In addition to the examples below, please see Jason Cuvelier’s excellent tutorial Here.
1955pluralpluribusslidemachine doublingslidetypeMD

Marker: A die-specific attribute used to identify a particular die, and useful for confirming a particular die variety. A marker can be many things from a mint mark’s position to a die crack or die chip, die scratches, die clash remnants, cuds, etc., all of which are unique to each die.

Master Die: The die that is made from the master hub. The master die is then used to create many working hubs, which in turn each create many working dies, from which coins are struck. Master dies often had to have the last 2 or 3 digits of the date engraved into them, so that the master hubs could be re-used in multiple years. These engraved portions often had anomalies and imperfections that would show up on each working hub and working die spawned from the master die. These anomalies are sometimes confused with hub doubling by novices. A master die could also be itself a doubled die. (See Master Die Doubling.)

Master Die Doubling: When a master die is itself a doubled die, (or exhibits another type of doubling such as engraving doubling) each working hub and subsequent working die created from this master die will also show this doubling. Since a doubled master die creates many working hubs and dies, this doubling will be very common, if not universal, during a specific year, and is therefore not a collectible form of doubling. There are many years in the Lincoln cent series exhibit master die doubling, with 1972 being the most well-known and most often mis-attributed as a collectible doubled die. 1972 had 2 master dies. One exhibited doubling and one did not. Therefore at least half of all 1972 cents will show this master die doubling. For more detailed information on the 1972 doubled master die please see Jason Cuvelier’s tutorial Here.  See also: Engraving Doubling.

Master Hub: A master hub is the original steel rod that holds the design for a coin. In the past, the master hub was created by using a reduction lathe that would engrave the design onto the hub from a galvano. The hub would have raised design elements on it, just like a struck coin has. The master hub would then be squeezed onto another blank steel rod creating that design in reverse relief. This would be the master die. In modern times, the master hub is created by transferring designs directly from a computer image. The master hub often was created without portions of the date on it, so it could be re-used in subsequent years. The missing parts were then engraved into the master die for that year.

Matte Proof: A French method for making proof coinage. Matte Proof Lincoln cents were struck from 1909-1916. Extra striking pressure and multiple strikes created extra-sharp details on these cents. These coins also exhibit sharply squared-off rim. The dies used for making these proofs were sand-blasted, as a way of polishing the die, so matte proofs also exhibit a textured grainy surface as a result of this practice. Matte Proof Lincolns had extremely low mintages and carry large premiums.  Image from Heritage Auction Galleries.
1915 matte proof obv2

Memorial Cent (Reverse): A Lincoln cent struck from 1959 until 2008, exhibiting the Lincoln Memorial on the reverse. This reverse was designed by Frank Gasparro, the 10th chief engraver of the U.S. Mint. His initials, FG, show at the bottom right of the memorial building on these cents.

Mid Die State: Cents struck in the middle of a die’s life-span. These cents will exhibit some signs of die deterioration, such as radial flow lines, and earlier stages of die cracks, die chips, etc.

Mid-Year Design Change: In the Lincoln cents series, there were several dates that saw an intentional change in design during the year. Some examples would be 1909 cents with and without the VDB, 2009 cents with 4 different reverse designs, and all of the years with both a large date and small date.(1960, 1970S, 1974, 1982)

Mini-mule: A coin with a wrong design on one side, but still appropriate for the denomination. For example, in the Lincoln cent series, these refer to the transitional design varieties and wrong design varieties. These coins exhibit reverse designs intended for other years, even though they are all memorial reverses.

Mint: The place where U.S. Coins are struck. Most Lincoln cents were struck at the Philadelphia, Denver, or San Francisco mints; however, between 1974 and 1986, some Lincoln cents were struck at the West Point mint. These cents also did not bear a mint mark, making them indistinguishable from those minted in Philadelphia. The word “mint” can also refer to the condition of a coin.

Mint Luster: The reflective qualities of a newly struck coin. The flow of metal toward the rim from the striking process creates tiny radial flow lines that reflect light. As a lustrous coin is tilted under light, the reflected light will appear to move around the coin. This is called “Cartwheel Luster.”  This cent below exhibits cartwheel mint luster. Photo donated by RLM’s Cents.

Mint Mark: A letter or letters that appear on a coin designating which mint struck the coin. On Lincoln cents, coins struck at the Philadelphia Mint have no mint mark. Cents struck at the Denver Mint bear a D below the date, and cents struck at the San Francisco mint bear an S below the date. For business strikes, mint marks were punch by hand into the working dies through 1989, thereby creating variance in position, orientation, depth of punch, and even re-punchings. In 1990, the mint mark became part of the master die for business strikes, putting an end to the aforementioned variations. For proof strikes, the practice of hand-punching mint marks into the working dies ceased in 1985.

Mint Mark Punch: The device used to add the mint mark to the working dies. The mint mark was punched by hand into the working dies for business strike Lincoln cents up through 1989. Starting in 1990, the mint mark was part of the master die, so punches were no longer used. For proof coinage, the practice of hand-punching the mint marks into the working dies stopped in 1985.

Mint Mark Style: Over the years, the font of mint marks changed many times. Commonly used “MMS#s” are proprietary to See D Mint Mark and S Mint Mark entries to see these variations.

Mint Set: A group of uncirculated coins packaged by the mint and released to collectors.

Mint State: A grading standard of 60-70. See our grading guide Here.

Mintage: The number of coins struck of any particular mint issue.

Misaligned Die: This refers to a coin that was struck by dies that were not in correct position in relation to each other. A coin struck by a misaligned die can be determined by noting a difference in its relative centered-ness between the obverse and reverse of a coin. Below is an example of a cent struck by slightly misaligned dies.  These do not command a premium unless the misalignment is severe enough to have part of the design cut off.  Photos courtesy of historyhound.

Misaligned Die Clash: A misaligned die clash is a die clash that happens with dies that are not properly lined up with each other. Clash remnants from these events can be rotated, offset, or even pivoted from the normal position. There was a sudden increase in these that occurred in the 1990s.

Misplaced Mint Mark: A mint mark that is punched into the die in an area outside of its normal location. On Lincoln cents, anything in the field below the date is considered acceptable. Many of these supposed misplaced mint marks are disagreed upon by experts. Some publications list what are most likely die chips in the date as misplaced mint marks. Others, like the 1958D 1MM-021, which has supposed punchings in the vest area, are still debated. 1953D 1MM-033 is a nice example of a D tilted and lightly punched into the vest area. It can be seen Here at

Modified Hub Doubling: Also called a class 7 doubled die, modified hub doubling occurs when a hub is altered in between hubbings of a die, or when a die is hubbed with one normal hub and one altered hub. This alteration can be intentional, like the grinding off of an element, or it can be accidental, like a piece of the hub breaking off. An example of class 7 doubling in the Lincoln cent series occurs in 1941, where we see many different dies exhibiting both a normal and a “broken” 2nd T of TRUST on the same die.
1941brokenT1 1941bokenTcoin2a

Motto: On a Lincoln cent, as well as other coinage, the motto almost always refers to “IN GOD WE TRUST,” although LIBERTY and E PLURIBUS UNUM are also technically mottos.

Mule: This is a coin which has mismatched obverse and reverse designs, not normally found on the same issue, such as the 2000 Sacagawea dollar/Washington quarter mule. Other than the transitional design and wrong designwide AM,” “close AM,” and “1988 RDV-006mini-mules, the only known major mule in the Lincoln series is a lone specimen of a 1959D with wheat reverse, which the mint has confirmed as genuine.

Mylar: A brand name for a clear polyester film used for, among other things, safe, long-term storage products for coins.