A coin is a small, flat, (usually, depending on the country or value) round piece of metal or plastic used primarily as a medium of exchange or legal tender. They are standardized in weight, and produced in large quantities at a mint in order to facilitate trade. They are most often issued by a government. Coins often have images, numerals, or text on them.
Coins are usually metal or an alloy, or sometimes made of synthetic materials. They are usually disc shaped. Coins made of valuable metal are stored in large quantities as bullion coins. Other coins are used as money in everyday transactions, circulating alongside banknotes. Usually the highest value coin in circulation (excluding bullion coins) is worth less than the lowest-value note. In the last hundred years, the face value of circulation coins has occasionally been lower than the value of the metal they contain, for example due to inflation. If the difference becomes significant, the issuing authority may decide to withdraw these coins from circulation, possibly issuing new equivalents with a different composition, or the public may decide to melt the coins down or hoard them (see Gresham's law).
Exceptions to the rule of face value being higher than content value also occur for some bullion coins made of copper, silver, or gold (and, rarely, other metals, such as platinum or palladium), intended for collectors or investors in precious metals. Examples of modern gold collector/investor coins include the British sovereign minted by the United Kingdom, the American Gold Eagle minted by the United States, the Canadian Gold Maple Leaf minted by Canada, and the Krugerrand, minted by South Africa. While the Eagle, Maple Leaf, and Sovereign coins have nominal (purely symbolic) face values, the Krugerrand does not.
Historically, a great quantity of coinage metals (including alloys) and other materials (e.g. porcelain) have been used to produce coins for circulation, collection, and metal investment: bullion coins often serve as more convenient stores of assured metal quantity and purity than other bullion.
Metal ingots, silver bullion or unmarked bars were probably in use for exchange among many of the civilizations that mastered metallurgy.
Coins were an evolution of "currency" systems of the Late Bronze Age, where standard-sized ingots, and tokens such as knife money, were used to store and transfer value. In the late Chinese Bronze Age, standardized cast tokens were made, such as those discovered in a tomb near Anyang. These were replicas in bronze of earlier Chinese currency, cowrie shells, so they were named Bronze Shell.
The earliest coins are mostly associated with Iron Age Anatolia of the late 7th century BC, and especially with the kingdom of Lydia. Early electrum coins (a variable mix of gold and silver, typically with a ratio of about 54% gold to 44% silver) were not standardized in weight, and in their earliest stage may have been ritual objects, such as badges or medals, issued by priests. The unpredictability of the composition of naturally occurring electrum implied that it had a variable value, which greatly hampered its development.
Most of the early Lydian coins include no writing ("legend" or "inscription"), only an image of a symbolic animal.
Many early Lydian and Greek coins were minted under the authority of private individuals and are thus more akin to tokens or badges than to modern coins, though due to their numbers it is evident that some were official state issues.
The first electrum coins issued by a monarch are those minted by king Alyattes of Lydia (died c. 560 BC), for which reason this king is sometimes mentioned as the originator of coinage.
The successor of Alyattes, king Croesus (r. c. 560–546 BC), became associated with great wealth in Greek historiography. He is credited with issuing the Croeseid, the first true gold coins with a standardized purity for general circulation. and the world's first bimetallic monetary system circa 550 BCE.
Herodotus mentioned the innovation made by the Lydians:
Coins spread rapidly in the 6th and 5th centuries BC, leading to the development of Ancient Greek coinage and Achaemenid coinage, and further to Illyrian coinage.
Standardized Roman currency was used throughout the Roman Empire. Important Roman gold and silver coins were continued into the Middle Ages (see Gold dinar, Solidus, Aureus, Denarius). Ancient and early medieval coins in theory had the value of their metal content, although there have been many instances throughout history of governments inflating their currencies by debasing the metal content of their coinage, so that the inferior coins were worth less in metal than their face value. Fiat money first arose in medieval China, with the jiaozi paper money. Early paper money was introduced in Europe in the later Middle Ages, but some coins continued to have the value of the gold or silver they contained throughout the Early Modern period. The penny was minted as a silver coin until the 17th century.
When Cyrus the Great (550–530 BC) came to power, coinage was unfamiliar in his realm. Barter and to some extent silver bullion was used instead for trade. The practice of using silver bars for currency also seems to have been current in Central Asia from the 6th century.
Cyrus the Great introduced coins to the Persian Empire after 546 BC, following his conquest of Lydia and the defeat of its king Croesus, who had put in place the first coinage in history. With his conquest of Lydia, Cyrus acquired a region in which coinage was invented, developed through advanced metallurgy, and had already been in circulation for about 50 years, making the Lydian Kingdom one of the leading trade powers of the time. It seems Cyrus initially adopted the Lydian coinage as such, and continued to strike Lydia's lion-and-bull coinage.
Original coins of the Achaemenid Empire were issued from 520 BCE – 450 BCE to 330 BCE. The Persian Daric was the first truly Achaemenid gold coin which, along with a similar silver coin, the Siglos, represented the bimetallic monetary standard of the Achaemenid Persian Empire.
The Achaemenid Empire already reached the doors of India during the original expansion of Cyrus the Great, and the Achaemenid conquest of the Indus Valley is dated to circa 515 BC under Darius I. An Achaemenid administration was established in the area. The Kabul hoard, also called the Chaman Hazouri hoard, is a coin hoard discovered in the vicinity of Kabul, Afghanistan, containing numerous Achaemenid coins as well as many Greek coins from the 5th and 4th centuries BCE. The deposit of the hoard is dated to the Achaemenid period, in approximately 380 BCE. The hoard also contained many locally produced silver coins, minted by local authorities under Achaemenid rule. Several of these issues follow the "western designs" of the facing bull heads, a stag, or Persian column capitals on the obverse, and incuse punch on the reverse.
According to numismatist Joe Cribb, these finds suggest that the idea of coinage and the use of punch-marked techniques was introduced to India from the Achaemenid Empire during the 4th century BCE. More Achaemenid coins were also found in Pushkalavati and in Bhir Mound.
- Punch-marked coin minted in the Kabul Valley under Achaemenid administration.
- Gandharan "bent-bar" punch-marked coin minted under Achaemenid administration, of the type found in large quantities in the Chaman Hazouri and the Bhir Mound hoards.
- Early punch-marked coins of Gandhara. Taxila-Gandhara region.
The Karshapana is the earliest punch-marked coin found in India, produced from at least the mid-4th century BC, and possibly as early as 575 BC, influenced by similar coins produced in Gandhara under the Achaemenid empire, such as those of the Kabul hoard, or other examples found at Pushkalavati and in Bhir Mound.
According to Aristotle (fr. 611,37, ed. V. Rose) and Pollux (Onamastikon IX.83), the first issuer of Greek coinage was Hermodike of Kyme.
A small percentage of early Lydian/Greek coins have a legend. A famous early electrum coin, the most ancient inscribed coin at present known, is from nearby Caria. This coin has a Greek legend reading phaenos emi sema  interpreted variously as "I am the badge of Phanes", or "I am the sign of light", or "I am the tomb of light", or "I am the tomb of Phanes". The coins of Phanes are known to be among the earliest of Greek coins, a hemihekte of the issue was found in the foundation deposit of the temple of Artemis at Ephesos (the oldest deposit of electrum coins discovered). One assumption is that Phanes was a wealthy merchant, another that this coin is associated with Apollo-Phanes and, due to the Deer, with Artemis (twin sister of the god of light Apollo-Phaneos). Although only seven Phanes type coins were discovered, it is also notable that 20% of all early electrum coins also have the lion of Artemis and the sun burst of Apollo-Phaneos.
Alternatively, Phanes may have been the Halicarnassian mercenary of Amasis mentioned by Herodotus, who escaped to the court of Cambyses, and became his guide in the invasion of Egypt in 527 or 525 BC. According to Herodotus, this Phanes was buried alive by a sandstorm, together with 50,000 Persian soldiers, while trying to conquer the temple of Amun–Zeus in Egypt. The fact that the Greek word "Phanes" also means light (or lamp), and the word "sema" also means tomb makes this coin a famous and controversial one.
Another candidate for the site of the earliest coins is Aegina, where Chelone ("turtle") coins were first minted circa 700 BC. Coins from Athens and Corinth appeared shortly thereafter, known to exist at least since the late 6th century BC.
- Coin of Phaselis, Lycia. Circa 550–530/20 BC.
- Coin of Lycia. Circa 520–470/60 BC
- Lycia coin. Circa 520-470 BC.
- Coin of Lesbos, Ionia. Circa 510–80 BC.
The Classical period saw Greek coinage reach a high level of technical and aesthetic quality. Larger cities now produced a range of fine silver and gold coins, most bearing a portrait of their patron god or goddess or a legendary hero on one side, and a symbol of the city on the other. Some coins employed a visual pun: some coins from Rhodes featured a rose, since the Greek word for rose is rhodon. The use of inscriptions on coins also began, usually the name of the issuing city.
The wealthy cities of Sicily produced some especially fine coins.
Amongst the first centers to produce coins during the Greek colonization of mainland Southern Italy (Magna Graecia) were Paestum, Crotone, Sybaris, Caulonia, Metapontum, and Taranto. These ancient cities started producing coins from 550BC to 510BC.
Amisano, in a general publication, including the Etruscan coinage, attributing it the beginning to about 560 BC in Populonia, a chronology that would leave out the contribution of the Greeks of Magna Graecia and attribute to the Etruscans the burden of introducing the coin in Italy. In this work, constant reference is made to classical sources, and credit is given to the origin of the Etruscan Lydia, a source supported by Herodotus, and also to the invention of coin in Lydia.
- Aegina coin type, incuse skew pattern. Circa 456/45–431 BC.
- Coin of Akanthos, Macedon. Circa 470-430 BC.
- Coin of Aspendos, Pamphylia, circa 465–430 BC.
- Coin from Korkyra. Circa 350/30–290/70 BC.
- Coin of Cyprus, circa 450 BCE.
Although many of the first coins illustrated the images of various gods, the first portraiture of actual rulers appears with the coinage of Lycia in the 5th century BC. No ruler had dared illustrating his own portrait on coinage until that time. The Achaemenids had been the first to illustrate the person of their king or a hero in a stereotypical manner, showing a bust or the full body but never an actual portrait, on their Sigloi and Daric coinage from circa 500 BC. A slightly earlier candidate for the first portrait is Themistocles, the Athenian general, who became a Governor of Magnesia on the Meander circa 465–459 BC for the Achaemenid Empire, although there is some doubt that his coins may have represented Zeus rather than himself. Themistocles may have been in a unique position in which he could transfer the notion of individual portraiture, already current in the Greek world, and at the same time wield the dynastic power of an Achaemenid dynasty who could issue his own coins and illustrate them as he wished. From the time of Alexander the Great, portraiture of the issuing ruler would then become a standard, generalized, feature of coinage.
- Coin of Themistocles as Governor of Magnesia. Obv: Barley grain. Rev: Possible portrait of Themistocles. Circa 465–459 BC.
- Portrait of Lycian ruler Kherei wearing the Persian cap on the reverse of his coins (ruled 410–390 BC).
- Portrait of Lycian ruler Erbbina wearing the Persian cap on the reverse of his coins (ruled 390–380 BC).
- Portrait of Lycian ruler Perikles facing (ruled 380-360 BC).
In China, early round coins appeared in the 4th century BC and were adopted for all China by Emperor Qin Shi Huang Di at the end of 3rd century BC. The round coin, the precursor of the familiar cash coin, circulated in both the spade and knife money areas in the Zhou period, from around 350 BC. Apart from two small and presumably late coins from the State of Qin, coins from the spade money area have a round hole and refer to the jin and liang units. Those from the knife money area have a square hole and are denominated in hua (化).
Although for discussion purposes the Zhou coins are divided up into categories of knives, spades, and round coins, it is apparent from archaeological finds that most of the various kinds circulated together.
The Hellenistic period was characterized by the spread of Greek culture across a large part of the known world. Greek-speaking kingdoms were established in Egypt and Syria, and for a time also in Iran and as far east as what is now Afghanistan and northwestern India. Greek traders spread Greek coins across this vast area, and the new kingdoms soon began to produce their own coins. Because these kingdoms were much larger and wealthier than the Greek city states of the classical period, their coins tended to be more mass-produced, as well as larger, and more frequently in gold. They often lacked the aesthetic delicacy of coins of the earlier period.
Still, some of the Greco-Bactrian coins, and those of their successors in India, the Indo-Greeks, are considered the finest examples of Greek numismatic art with "a nice blend of realism and idealization", including the largest coins to be minted in the Hellenistic world: the largest gold coin was minted by Eucratides (reigned 171–145 BC), the largest silver coin by the Indo-Greek king Amyntas Nikator (reigned c. 95–90 BC). The portraits "show a degree of individuality never matched by the often bland depictions of their royal contemporaries further West" (Roger Ling, "Greece and the Hellenistic World").
- Seleucus Nicator (312–281 BC), Ai Khanoum.
- Antiochus I (281–261 BC), Ai Khanoum.
- Bilingual coin of Indo-Greek king Antialcidas (105–95 BC).
- Bilingual coin of Agathocles of Bactria with Hindu deities, circa 180 BC.
Coinage followed Greek colonization and influence first around the Mediterranean and soon after to North Africa (including Egypt), Syria, Persia, and the Balkans. Coins came late to the Roman Republic compared with the rest of the Mediterranean, especially Greece and Asia Minor where coins were invented in the 7th century BC. The currency of central Italy was influenced by its natural resources, with bronze being abundant (the Etruscans were famous metal workers in bronze and iron) and silver ore being scarce. The coinage of the Roman Republic started with a few silver coins apparently devised for trade with Celtic in northern Italy and the Greek colonies in Southern Italy, and heavy cast bronze pieces for use in Central Italy. The first Roman coins, which were crude, heavy cast bronzes, were issued c. 289 BC. Amisano, in a general publication, including the Etruscan coinage, attributing it the beginning to about 550 BC in Populonia, a chronology that would leave out the contribution of the Greeks of Magna Graecia and attribute to the Etruscans the burden of introducing the coin in Italy. In this work, constant reference is made to classical sources, and credit is given to the origin of the Etruscan Lydia, a source supported by Herodotus, and also to the invention of coin in Lydia.
- Sestertius of Marcus Clodius Pupienus Maximus, AD 238
- Set of three Roman aurei depicting the rulers of the Flavian dynasty. Top to bottom: Vespasian, Titus and Domitian. AD 69–96
- Silver Drachma of Mehrdad (Mithridates I) of Persian Empire of Parthia, 165 BC
The first European coin to use Arabic numerals to date the year in which the coin was minted was the St. Gall silver Plappart of 1424.
- Lombardic Tremissis depicting Saint Michael, AD 688-700
- Silver coin of Borandukht of Persian Sassanian Empire, AD 629
- Silver Dirham of the Umayyad Caliphate, 729; minted by using Persian Sassanian framework
- Abbasid coin, c. 1080s
- Almoravid coin, 1138–1139
- Brunswick-Wolfenbüttel Thaler minted in 1629
- Japanese local currency Genbun Inari Koban Kin, c. 1736–1741
- 1768 silver Spanish Dollar, or eight reales coin (the “piece of eight” of pirate fame), minted throughout the Spanish Empire
- Ottoman coin, 1818
- One Rupee coin issued by the East India Company, 1835
Most coins presently are made of a base metal, and their value comes from their status as fiat money. This means that the value of the coin is decreed by government fiat (law), and thus is determined by the free market only in as much as national currencies are used in domestic trade and also traded internationally on foreign exchange markets. Thus, these coins are monetary tokens, just as paper currency is: they are usually not backed by metal, but rather by some form of government guarantee. Some have suggested that such coins not be considered to be "true coins" (see below). Thus, there is very little economic difference between notes and coins of equivalent face value.
Coins may be in circulation with fiat values lower than the value of their component metals, but they are never initially issued with such value, and the shortfall only arises over time due to inflation, as market values for the metal overtake the fiat declared face value of the coin. Examples are the pre-1965 US dime, quarter, half dollar, and dollar (nominally containing slightly less than a tenth, quarter, half, and full ounce of silver, respectively), US nickel, and pre-1982 US penny. As a result of the increase in the value of copper, the United States greatly reduced the amount of copper in each penny. Since mid-1982, United States pennies are made of 97.5% zinc, with the remaining 2.5% being a coating of copper. Extreme differences between fiat values and metal values of coins cause coins to be hoarded or removed from circulation by illicit smelters in order to realize the value of their metal content. This is an example of Gresham's law. The United States Mint, in an attempt to avoid this, implemented new interim rules on December 14, 2006, subject to public comment for 30 days, which criminalized the melting and export of pennies and nickels. Violators can be fined up to $10,000 and/or imprisoned for up to five years.
A coin's value as a collector's item or as an investment generally depends on its condition, specific historical significance, rarity, quality, beauty of the design and general popularity with collectors.
Collector catalogs often include information about coins to assists collectors with identifying and grading.
Coins can be used as creative medium of expression – from fine art sculpture to the penny machines that can be found in most amusement parks.
This has been a particular problem with nickels and dimes (and with some comparable coins in other currencies) because of their relatively low face value and unstable commodity prices.
31 CFR § 82.2(b) goes on to state that: "The prohibition contained in § 82.1 against the treatment of 5-cent coins and one-cent coins shall not apply to the treatment of these coins for educational, amusement, novelty, jewelry, and similar purposes as long as the volumes treated and the nature of the treatment makes it clear that such treatment is not intended as a means by which to profit solely from the value of the metal content of the coins."
Debasement and clipping
Throughout history, monarchs and governments have often created more coinage than their supply of precious metals would allow if the coins were pure metal.
The United States is unusual in that it has only slightly modified its coinage system (except for the images and symbols on the coins, which have changed a number of times) to accommodate two centuries of inflation.
Some denominations of circulating coins that were formerly minted in the United States are no longer made.
Circulating coins commonly suffered from "shaving" or "clipping": the public would cut off small amounts of precious metal from their edges to sell it and then pass on the mutilated coins at full value. Unmilled British sterling silver coins were sometimes reduced to almost half their minted weight. This form of debasement in Tudor England was commented on by Sir Thomas Gresham, whose name was later attached to Gresham's law. The monarch would have to periodically recall circulating coins, paying only the bullion value of the silver, and reminting them. This, also known as recoinage, is a long and difficult process that was done only occasionally. Many coins have milled or reeded edges, originally designed to make it easier to detect clipping.
Some convicted criminals from the British Isles who were sentenced to transportation to Australia in the 18th and 19th centuries used coins to leave messages of remembrance to loved ones left behind in Britain.
Features of modern coins
The side of a coin carrying an image of a monarch, other authority (List of people on coins), or a national emblem is called the obverse (colloquially, heads); the other side, carrying various types of information, is called the reverse (colloquially, tails). The year of minting is usually shown on the obverse, although some Chinese coins, most Canadian coins, the pre-2008 British 20p coin, the post-1999 American quarter, and all Japanese coins are exceptions.
The relation of the images on the obverse and reverse of a coin is the coin's orientation.
Bimetallic coins are sometimes used for higher values and for commemorative purposes. In the 1990's, France used a tri-metallic coin. Common circulating bimetallic examples include the €1, €2, British £1, £2 and Canadian $2 and several peso coins in Mexico.
The exergue is the space on a coin beneath the main design, often used to show the coin's date, although it is sometimes left blank or contains a mint mark, privy mark, or some other decorative or informative design feature. Many coins do not have an exergue at all, especially those with few or no legends, such as the Victorian bun penny.
Not all coins are round; they come in a variety of shapes. The Australian 50-cent coin, for example, has twelve flat sides. Some coins have wavy edges, e.g. the $2 and 20-cent coins of Hong Kong and the 10-cent coins of Bahamas. Some are square-shaped, such as the 15-cent coin of the Bahamas and the 50-cent coin from Aruba. During the 1970's, Swazi coins were minted in several shapes, including squares, polygons, and wavy edged circles with 8 and 12 waves.
- Scalloped coin of Israel
- 1996 one cent coin from Belize
- Decagonal two Piso Philippine coin 1990
Some other coins, like the British 20 and 50 pence coins and the Canadian Loonie, have an odd number of sides, with the edges rounded off. This way the coin has a constant diameter, recognizable by vending machines whichever direction it is inserted.
A triangular coin with a face value of £5 (produced to commemorate the 2007/2008 Tutankhamun exhibition at The O2 Arena) was commissioned by the Isle of Man: it became legal tender on 6 December 2007. Other triangular coins issued earlier include: Cabinda coin, Bermuda coin, 2 Dollar Cook Islands 1992 triangular coin, Uganda Millennium Coin and Polish Sterling-Silver 10-Zloty Coin.
Some medieval coins, called bracteates, were so thin they were struck on only one side.
Many coins over the years have been manufactured with integrated holes such as Chinese "cash" coins, Japanese coins, Colonial French coins, etc. This may have been done to permit their being strung on cords, to facilitate storage and being carried.
- 1917 French coin with integrated hole
- Chinese cash coin, 1102–1106
- 1941 Palestine coin
- Modern-day Japanese 5-yen coin
- 1924 East African coin
The Royal Canadian Mint is now able to produce holographic-effect gold and silver coinage. However, this procedure is not limited to only bullion or commemorative coinage. The 500 yen coin from Japan was subject to a massive amount of counterfeiting. The Japanese government in response produced a circulatory coin with a holographic image.
The Royal Canadian Mint has also released several coins that are colored, the first of which was in commemoration of Remembrance Day.
An example of non-metallic composite coins (sometimes incorrectly called plastic coins) was introduced into circulation in Transnistria on 22 August 2014. Most of these coins are also non-circular, with different shapes corresponding to different coin values.
For a list of many pure metallic elements and their alloys which have been used in actual circulation coins and for trial experiments, see coinage metals.
Physics and chemistry
To flip a coin to see whether it lands heads or tails is to use it as a two-sided dice in what is known in mathematics as a Bernoulli trial: if the probability of heads (in the parlance of Bernoulli trials, a "success") is exactly 0.5, the coin is fair.
Coins can also be spun on a flat surface such as a table.
Iron and copper coins have a characteristic metallic smell that is produced upon contact with oils in the skin.
Piloncitos are small engraved gold coins found in the Philippines.