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A pattern coin is a coin which has not been approved for release, but produced to evaluate a proposed coin design.  They are often off-metal strike (using metals of lower value to test out the dies), to proof standard or piedforts. Many coin collectors collect and study pattern coins because of their historical importance. Many of the world's most valuable coins are pattern coins; nearly 25 of the pieces listed in 100 Greatest US Coins are pattern coins. 
The first English coin that can be identified with certainty is a groat, originally worth fourpence. This piece, an example of which was illustrated and sold in the Dodsley Cuff sale of the mid-19th century, had crowns in place of the usual three pellets in each quarter of the reverse.[ citation needed ]
Patterns are particularly identifiable and exist in larger numbers from the reign of Elizabeth I onwards. The experimental base metal issues of all coinage prior to the mid-18th century have been well preserved.[ citation needed ]
Boulton's mint in Soho produced large quantities of patterns, which were supplemented by Taylor some fifty or so years later from the same dies. [ citation needed ]
After the Declaration of Independence was signed on July 4, 1776, discussion arose over what sort of currency should be adopted in the United States. At the time, people in North America relied upon a mixture of foreign coins, none of which were struck to a consistent standard, making day-to-day financial transactions difficult. In 1783, Congress resolved to create a mint, tasking Superintendent of Finance Robert Morris with developing a plan for a system of coinage. The first coins struck by the United States – the Nova Constellatio patterns – were made to illustrate this plan. 
In 1792 the United States Mint opened in Philadelphia. In that year several more patterns were created, including the half dime, then known as a "half disme". It is believed that c. 1,500 pieces were struck as patterns, and that these patterns themselves entered circulation during the next decade.[ citation needed ]
Over the next 40 years, more patterns were created but there is little information currently known about these pieces. Technically, these coins were not patterns but rather off-metal strikes, with the coins struck in a different metal than those destined for general use in circulation. An example is an 1807 Half Eagle, or five dollar gold piece struck in copper.
Starting in 1836, more patterns were created by the United States Mint in Philadelphia. These consisted of several types of patterns:
One example of a pattern coin for proposed coinage is the half-union, a gold pattern coin with a face value of 50 U.S. dollars that was minted in 1877 and weighed 2.5 ounces (71 g). The U.S. Mint deemed the idea of a 2.5-ounce gold coin infeasible, and only two were ever minted.  
Transitional pieces are patterns dated before coins with the new design officially went into circulation. These were often produced during final stage of the pattern process, used to present the newly adopted design to the public. One famous example is the 1856 Flying Eagle cent, although that coin has been commonly and incorrectly believed to be regular issue due to its high mintage for collectors.[ citation needed ]
Fantasy pieces include many struck in the 1860s and 1870s as patterns and sold to numismatists for the sole purpose of raising cash for the mint. This practice ended in the 1880s, when the U.S. Mint enforced regulations to prevent the sale of pattern coins. 
The U.S. Mint experiments with new coinage occasionally, such as when silver was removed from coin designs. The Mint began using dies with Martha Washington for trial strikings, since they would not be confused with real circulating money  since they do not resemble money. Thus, no restrictions exist on the sale of Martha Washington pieces. Mint-produced modern patterns are very rare, with only a few pieces existing in private collections. The United States mint has placed restrictions on the sale of modern patterns that do resemble coins, such as the 1974 aluminum cent.[ citation needed ] One of the most expansive collections of American pattern coins is the Harry W. Bass, Jr. collection housed at the American Numismatic Association Money Museum in Colorado Springs, Colorado. 
Pattern coins of France and of French-speaking countries such as Monaco are described by the French term essai. The essai coins of New Hebrides are of interest to collectors of British Commonwealth coinage, as New Hebrides gained independence in 1980 as the Republic of Vanuatu.
The word essai is found inscribed on the pattern coins of Namibia along with the German word Probe.[ citation needed ]
The British crown was a denomination of sterling coinage worth 1/4 of one pound, or 5 shillings, or 60 (old) pence. The crown was first issued during the reign of Edward VI, as part of the coinage of the Kingdom of England.
A nickel is a five-cent coin struck by the United States Mint. Composed of cupronickel, the piece has been issued since 1866. Its diameter is 0.835 inches (21.21 mm) and its thickness is 0.077 inches (1.95 mm).
The dollar coin is a United States coin with a face value of one United States dollar. Dollar coins have been minted in the United States in gold, silver, and base metal versions. Dollar coins were first minted in the United States in 1794.
The two-cent piece was produced by the Mint of the United States for circulation from 1864 to 1872 and for collectors in 1873. Designed by James B. Longacre, there were decreasing mintages each year, as other minor coins such as the nickel proved more popular. It was abolished by the Mint Act of 1873.
A double eagle is a gold coin of the United States with a denomination of $20. The coins are 34 mm x 2 mm and are made from a 90% gold and 10% copper alloy and have a total weight of 1.0750 troy ounces.
The half dime, or half disme, was a silver coin, valued at five cents, formerly minted in the United States.
The United States Bicentennial coinage is a set of circulating commemorative coins, consisting of a quarter, half dollar and dollar struck by the United States Mint in 1975 and 1976. Regardless of when struck, each coin bears the double date 1776–1976 on the normal obverses for the Washington quarter, Kennedy half dollar and Eisenhower dollar. No coins dated 1975 of any of the three denominations were minted.
The Eisenhower dollar was a one-dollar coin issued by the United States Mint from 1971 to 1978; it was the first coin of that denomination issued by the Mint since the Peace dollar series ended in 1935. The coin depicts President Dwight D. Eisenhower on the obverse, and on the reverse a stylized image honoring the 1969 Apollo 11 Moon mission based on the mission patch designed by astronaut Michael Collins. Both sides were designed by Frank Gasparro. It is the only large-size U.S. dollar coin whose circulation strikes contained no silver.
The American twenty-cent piece is a coin struck from 1875 to 1878, but only for collectors in the final two years. Proposed by Nevada Senator John P. Jones, it proved a failure due to confusion with the quarter, to which it was close in both size and value.
The Seated Liberty dollar was a dollar coin struck by the United States Mint from 1840 to 1873 and designed by its chief engraver, Christian Gobrecht. It was the last silver coin of that denomination to be struck before passage of the Coinage Act of 1873, which temporarily ended production of the silver dollar for American commerce. The coin's obverse is based on that of the Gobrecht dollar, which had been minted experimentally from 1836 to 1839. However, the soaring eagle used on the reverse of the Gobrecht dollar was not used; instead, the United States Mint (Mint) used a heraldic eagle, based on a design by late Mint Chief Engraver John Reich first utilized on coins in 1807.
The Indian Head cent, also known as an Indian Head penny, was a one-cent coin ($0.01) produced by the United States Bureau of the Mint from 1859 to 1909. It was designed by James Barton Longacre, the Chief Engraver at the Philadelphia Mint.
The Kennedy half dollar, first minted in 1964, is a fifty-cent coin currently issued by the United States Mint. Intended as a memorial to the assassinated 35th president of the United States John F. Kennedy, it was authorized by Congress just over a month after his death. Use of existing works by Mint sculptors Gilroy Roberts and Frank Gasparro allowed dies to be prepared quickly, and striking of the new coins began in January 1964.
This glossary of numismatics is a list of definitions of terms and concepts relevant to numismatics and coin collecting, as well as sub-fields and related disciplines, with concise explanations for the beginner or professional.
The quarter eagle was a gold coin issued by the United States with a value of two hundred and fifty cents, or two dollars and fifty cents. It was given its name in the Coinage Act of 1792, as a derivation from the US ten-dollar eagle coin.
The Shield nickel was the first United States five-cent piece to be made out of copper-nickel, the same alloy of which American nickels are struck today. Designed by James B. Longacre, the coin was issued from 1866 until 1883, when it was replaced by the Liberty Head nickel. The coin takes its name from the motif on its obverse, and was the first five-cent coin referred to as a "nickel"—silver pieces of that denomination had been known as half dimes.
The half union was a United States pattern coin with a face value of fifty U.S. Dollars. It is often thought of as one of the most significant and well-known patterns in the history of the U.S. Mint. The basic design, featuring Liberty on the obverse, was slightly modified from the similar $20 "Liberty Head" Double Eagle, which was designed by James B. Longacre and minted from 1849 to 1907.
The Coinage Act of 1965, Pub. L. 89–81, 79 Stat. 254, enacted July 23, 1965, eliminated silver from the circulating United States dime and quarter dollar coins. It also reduced the silver content of the half dollar from 90 percent to 40 percent; silver in the half dollar was subsequently eliminated by a 1970 law.
The Fugio cent, also known as the Franklin cent, is the first official circulation coin of the United States. Consisting of 0.36 oz (10 g) of copper and minted dated 1787, by some accounts it was designed by Benjamin Franklin. Its design is very similar to a 1776 Continental Currency dollar coin that was produced in pattern pieces as potential Continental currency but was never circulated.
The copper-nickel three-cent piece, often called a three-cent nickel piece or three-cent nickel, was designed by US Mint Chief Engraver James B. Longacre and struck by the United States Bureau of the Mint from 1865 to 1889. It was initially popular, but its place in commerce was supplanted by the five-cent piece, or nickel.
The three-cent silver, also known as the three-cent piece in silver or trime, was struck by the Mint of the United States for circulation from 1851 to 1872, and as a proof coin in 1873. Designed by the Mint's chief engraver, James B. Longacre, it circulated well while other silver coinage was being hoarded and melted, but once that problem was addressed, became less used. It was abolished by Congress with the Coinage Act of 1873.