coin terms

Coin terms

Letter M

mail bid sale

An auction sale where bidding is limited to bids by mail. (Today, that also may include by phone, fax, or email.)

major variety

A coin that is easily recognized as having a major difference from other coins of the same design, type, date, and mint.

market grading

A numerical grade that matches the grade at which a particular coin generally is traded in the marketplace.


Imperfections acquired after striking. These range from tiny to large hits and may be caused by other coins or foreign objects.

master die

The main die produced from the master hub. Many working hubs are prepared from this single die.

master hub

The original hub created by the portrait lathe. Master dies are created from this hub.

Matte Proof

An experimental Proof striking, produced by the U.S. Mint mainly from 1907 to 1916, which has sandblasted or acid-pickled surfaces. These textured surfaces represented a radical departure from brilliant Proofs, having even less reflectivity than business strikes.

medal press

A high-pressure coining press acquired by the U.S. Mint, circa 1854-1858, to strike medals, patterns, restrikes, and some regular-issue Proofs.

medium date (MD)

Term referring to the size of the digits of the date on a coin. (Use of this term implies that a large or small date exists for that coin or series.)

medium letters (ML)

Term referring to the size of the lettering of the date on a coin. (Use of this term implies that large or small letters exist for that coin or series.)

melt or melt value

Slang term for the intrinsic value of a particular numismatic item.
Mercury dime

Common name for the Winged Liberty Head dime issued from 1916 until 1945. The A.A. Weinman motif was quickly compared to the Roman god Mercury and the name stuck with the public.

metal stress lines

Radial lines, sometimes visible, that result when the metal flows outward from the center of the planchet during the minting process.

milling mark

A mark that results when the reeded edge of one coin hits the surface of another coin. Such contact may produce just one mark or a group of staccato-like marks.

minor variety

A coin that has a minor difference from other coins of the same design, type, date, and mint. This minor difference is barely discernible to the unaided eye. The difference between a major variety and a minor variety is a matter of degree.


A coining facility.

mint bloom

Original luster that is still visible on a coin.

mint error

See “error coins in coin collecting”

mint mark

Variation of mintmark

mint set

A set of Uncirculated coins from a particular year comprising coins from each Mint. (Usually, this term refers to government issued Mint Sets, although for many years, it has been loosely used for any set of Uncirculated coins from a particular year. Also, the government Mint Sets issued from 1947 until 1958 were double sets.)

mint set toning

This term refers to the colors and patterns coins have acquired from years of storage in the cardboard holders in which Mint Sets were issued from 1947-1958. Since 1959, Mint Sets have been issued in plastic sleeves, thus they do not tone as spectacularly.

Mint State

The term corresponding to the numerical grades MS-60 through MS-70, used to denote a business strike coin that never has been in circulation. A Mint State coin can range from one that is covered with marks (MS-60) to a flawless example (MS-70).


The number of coins of a particular date struck at a given mint during a particular year. (This may not equal the “official” mintage for that calendar year, especially for pre-1840 coinage. The Mint reported coins struck in the calendar year, regardless of the date(s) on the issue. For instance, the 1804-dated dollar was included in Proof Sets struck in 1834 because the “official” mintage figures for 1804 included silver dollars although it is now known that these were dated 1803 or possibly even earlier.)


The tiny letter(s) stamped into the dies to denote the mint at which a particular coin was struck.


Term applied to the error coins that have striking irregularities.

mishandled Proof

A Proof coin that has been circulated, cleaned, or otherwise reduced to a level of preservation below PR-60.

Miss Liberty

Term applied to the various incarnations of the emblematic Liberty represented on United States coinage.


Slang for an incredible coin, usually one that grades MS/PR-67 or higher. A secondary use is as an adjective, such as monster luster or monster color.


Slang for an incredible coin, usually one that grades MS/PR-67 or higher.

Morgan dollar

The common term used for the Liberty Head silver dollar struck from 1878 until 1904 and again in 1921. George Morgan was the assistant engraver but his design was selected over William Barber’s for the dollar.

Morgan was passed over for the Chief Engraver’s job when William Barber died in 1879. Charles Barber, William’s son, received the job and Morgan remained an assistant until Charles died in 1918. Morgan was then elevated to position of Chief Engraver, which he held until his death in January, 1925.

mottled toning

Uneven toning, usually characterized by splotchy areas of drab colors.

Mule Error

This is a rare Mint error where the obverse die is of one coin and the reverse die is of another coin. The most famous of the Mule errors is a Sacagawea dollar/Washington quarter Mule, where a Washington quarter obverse is paired with a Sacagawea reverse.


See Also —   double-struck


A term used to describe a coin that has been damaged to the point where it no longer can be graded.

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