What Metals and Materials are Used in US Coins and Banknotes?

By G.P. Thomas

Topics Covered

History of Metal Coins in USA
Requirements for a Coinage Metal
Metals Used in Coins
Materials Used in USA Banknotes
Specifications for Legal Tender Coins in USA
How are Metal Coins Produced in USA?
Sources

History of Metal Coins in USA

The United States dollar (USD/US$) is also referred to as American dollar or the U.S. dollar. It is the official currency of the United States of America and its overseas territories. One American dollar is divided into 100 smaller units called cents.

Here is a brief look into the history of currency in the U.S.:

  • In 1781, Congress chartered the Bank of North America in Philadelphia as the first national bank. It was to support the financial operations of the fledgling government.
  • In 1785, Congress adopted the dollar as the monetary unit of the United States.
  • In 1792, the Coinage Act of 1792 created the U.S. Mint and established a federal monetary system with set denominations for coins, and specified the value of each coin in gold, silver, or copper.
  • In 1861, the federal government circulated the first paper money.

Another day, another dollar...but how are they made? Credit: © 2013 Photos.com, a division of Getty Images. All rights reserved.

Requirements for a Coinage Metal

The metals used to make coins are specifically chosen to serve long term. Coins have a purpose and some special requirements based on the conditions they will encounter. The metal used must thus have excellent wear resistance and anti-corrosion properties. Hence coins are usually made using base metal alloys.

Care should be taken to ensure that the value of the metal within a coin is greater than the face value. This would allow smelters to melt the coins and re-sell them. To counter this problem, coins are now made from combination of metals such as cupro-nickel. Cupro-nickel is silver in color with hard wearing and excellent striking properties, which are essential for the design of the coin.

Metals Used in Coins

Coins available from the United States mint are made from a variety of metals. Exotic metals such as silver and gold were used by the United States mint for making coins. However, due to the increasing price of these metals, they are only used now for making bullion coins or collectors’ coins. Other metals such as copper, nickel and zinc are used to make ordinary coins. Initially, pennies were made from copper. But during wartime years the penny was even made from steel mixed with zinc so as to conserve copper for making weapons and shell casings. Today all the pennies are made primarily from copper plated zinc.

Coins that have a silver color should not be mistaken for silver. These silver-colored coins are the quarter, nickel and dime coins, made using copper-nickel combination. In the past, only the faces of the coins were plated, which caused the coins to rust. However, advanced technology has eliminated such problems. Today steel is added in the making of all the coins. Metal prices have a strong control over which metal is used even if there are new technologies available.

Materials Used in USA Banknotes

The Bureau of Engraving and Printing (BEP) develops and produces United States currency notes. American banknotes or currency paper is made of 75% cotton and 25% linen. This is what gives United States currency its distinct look and feel. The paper and ink used in the production of U.S. paper currency is as distinct as its design. The quality of the paper is very high as it would take almost 4,000 double folds (first forwards and then backwards) before a note will tear.

The BEP receives the paper in brown paper-wrapped loads of 20,000 sheets i.e. 2 pallets of 10,000 sheets. Each sheet is tracked by the BEP as it passes through the production process. The total inventory of 20,000 sheets is constantly monitored to ensure that every sheet is accounted for. Currency paper is specifically made for the BEP by Crane Paper Company. For denominations of $5 and above, a security thread and watermark are already built into the paper when it is received.

The approximate weight of a note, regardless of denomination, is 1g. In 1929, small-sized notes were introduced in green color, as a pigment of that color was readily available in large quantities. The color was also known to have high resistance to chemical and physical changes. Psychologically speaking, green was identified with the strong and stable credit of the Government. Soon these notes acquired the nickname "greenback".

The currency design is updated with added complexity from time to time to make counterfeiting more difficult. It has also been updated with features that will aid the public in easily distinguishing the denomination. These features were designed keeping in mind the needs of people with visual impairments.

Specifications for Legal Tender Coins in USA

The following table provides the specifications regarding legal tender coins in the USA.

Denomination Metal used Composition (%) Weight (g) Diameter Thickness (mm) Edge No. of Reeds
Cent Copper -plated Zinc 2.5 Cu Balance Zn 2.500 0.750 in. (19.05 mm) 1.55 Plain N/A
Nickel Cupro-Nickel 25 Ni Balance Cu 5.000 0.835 in. (21.21 mm) 1.95 Plain N/A
Dime Cupro-Nickel 8.33 Ni Balance Cu 2.268 0.705 in. (17.91 mm) 1.35 Reeded 118
Quarter Dollar Cupro-Nickel 8.33 Ni Balance Cu 5.670 0.955 in. (24.26 mm) 1.75 Reeded 119
Half Dollar Cupro-Nickel 8.33 Ni Balance Cu 11.340 1.205 in. (30.61 mm) 2.15 Reeded 150
Presidential $1 Manganese-Brass 88.5 Cu 6 Zn 3.5 Mn 2Ni 8.1 1.043 in. (26.49 mm) 2.00 Edge- Lettering N/A
Native American $1 Coin Manganese-Brass 88.5% Cu 6 Zn 3.5 Mn 2 Ni 8.1 1.043 in. (26.49 mm) 2.00 Edge-Lettering N/A

How are Metal Coins Produced in USA?

All U.S. coinage is minted by the United States Mint. The production of millions of metal coins per day is a complex process that requires men and machine to work together efficiently and in unison.

The six main steps in the manufacture of American coins are given below:

  • The first step is known as blanking. Blanks are punched from coiled strips of metal measuring 13 in by 1,500 ft in a blanking press. The leftover webbing is cut up and recycled. The cent is the only coin that is stamped onto pre-made blanks.
  • The next step involves annealing, washing and drying of the blanks. The blanks are heated in an annealing furnace to soften them, and then they are sent through a washer and dryer.
  • The third step is called upsetting, where the good blanks are passed through an upsetting mill so as to raise a rim around their edges.
  • The fourth step is striking. The blanks are passed to a coining press. In the press, they are stamped with the designs and inscriptions which provide them the authentic appearance of United States coins.
  • The fifth step is inspection during which press operators use magnifying glasses to spot-check each batch of newly struck coins.
  • In the sixth and final step the coins have to counted and bagged. This is done using an automatic counting machine which counts the coins and drops them into large bags. Forklifts transport the pallets of sealed bags to vaults for storage. From there trucks, take the new coins to Federal Reserve Banks, and later to local banks.

Sources


Date Added: Jan 24, 2013 | Updated: Dec 12, 2013
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