Glossary of Numismatic Terms

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mail-bid sale: Similar to an auction, but all bids and transactions are completed through the mail, online through the Internet or by telephone; no bidding is conducted "in person."

Maple Leaf: A brand of gold, silver and platinum bullion coins of Canada. Issued in many different designs and sizes, with several different degrees of fineness of .999 or finer.

Maria Theresia taler: An Austrian silver trade coin dated 1780, but struck repeatedly since then with the one date.

master die: A metal punch used to produce "working hubs," which are then used to produce "working dies." See also die and hub.

master hub: A metal punch used to produce "master dies." See also hub and master die.

Matte Proof: Especially U.S. gold coins of 1908 to 1916, coins produced from dies entirely sandblasted with no mirror surfaces. See also frost and Proof.

maverick: An unidentifiable example, generally referring to a token.

medal: Usually a piece of metal, marked with a design or inscription, made to honor a person, place or event; not intended to pass as money.

medalet: Depending on sources, a small medal no larger than 1 inch in diameter or a medal 35 millimeters in diameter or less.

medallion: A large Roman presentation piece of the fifth century. Sometimes used for a large medal, usually 3 or more inches in diameter.

medieval coin: A coin struck from about A.D. 500 to 1500.

Mercury: The unofficial nickname given to the Winged Liberty Head dime of 1916-45. The designer never intended the coin to depict Mercury, a male Greek god with wings on his ankles. The bust on the dime is an allegorical female Liberty Head figure with a winged cap. Also, some coins have been plated outside the Mint with mercury to give them a "Prooflike" appearance; mercury metal is highly toxic and these coins should be handled with caution.

microprinting: Extremely small lettering difficult to discern with the naked eye, used as an anti-counterfeiting device on paper money.

milling; milled coin: Milling refers to the devices on the edge of a coin; a milled coin is one struck by machine. They are related due to the rise of the importance of the collar with machine-produced coinage.

minor coin: A silver coin of less than crown weight, or any coin struck in base metal.

Mint luster: The sheen or bloom on the surface of an Uncirculated numismatic object resulting from the centrifugal flow of metal caused by striking with dies. Mint luster or bloom is somewhat frosty in appearance as opposed to the mirrorlike smoothness of the field of a Proof. See also luster.

Mint mark: A letter or other symbol, sometimes of a privy nature, indicating the Mint of origin.

Mint set: Common term for an Uncirculated Mint set, an official set containing one of each coin struck during a given year.

mirror: Highly reflective surface or field of a coin; usually mirror field with frosted relief.

model, plaster: A clay or plaster three-dimensional design for a coin or medal.

modern coin: Traditionally, a coin struck after about A.D. 1500. The term is also used to describe recent U.S. coins as contrasted with older U.S. coins, though no universally accepted definition defines when the modern era of U.S. coinage began.

money: A medium of exchange.

mule: A coin, token, medal or note whose obverse/face is not matched with its official or regular reverse/back. Denominational mules bear designs intended for different denominations, such as the mule struck with the obverse of a Washington quarter dollar and reverse of a Sacagawea dollar. A design mule is made from two designs for the same denomination but intended for use together, such as the Uncirculated 2008-W American Eagle silver dollar with the Reverse of 2007 (subtle differences in letter help distinguish the two reverse subtypes). Some Canadian mules pair a coin design and a medal design instead of two coin or two medal designs.