The coinage metals comprise, at a minimum, those metallic chemical elements which have historically been used as components in alloys used to mint coins. The term is not perfectly defined, however, since a number of metals have been used to make "demonstration coins" which have never been used to make monetized coins for any nation-state, but could be. Some of these elements would make excellent coins in theory (for example, zirconium), but their status as coin metals is not clear. In general, because of problems caused when coin metals are intrinsically valuable as commodities, there has been a trend in the 21st century toward use of coinage metals of only the least exotic and expensive types.
Historically, most coinage metals (or alloys) are from the three nonradioactive members of group 11 of the periodic table: copper, silver and gold, the copper usually being augmented with tin and often other metals to form bronze. Gold, silver and bronze or copper were the coinage metals of the ancient world, and most medieval coins.
All western histories of coins begin invention at some time slightly before or after 700 BC, in Aegina Island, or, according to others, in Ephesus, Lydia, 650 BC. Ancient India in circa 6th century BC, was one of the earliest issuers of coins in the world.
Since that time, coins have been the most universal embodiment of money. These first coins were made of electrum, a naturally occurring pale yellow mixture of gold and silver that was further alloyed with silver and copper.
However, the Persian daric was the first gold coin which, along with a similar silver coin, the siglos, (From Ancient Greek σίγλος, Hebrew שֶׁקֶל (shékel))represented the bimetallic monetary standard of the Achaemenid Persian Empire which has continued till today.Also, the Persian coins were very well known in the Persian and Sassanids era. Most notably, in Susa and in Ctesiphon.
However, there are many more, even for coins made from intrinsically precious metals. Precious metals are always used in bullion coins and some collectable coins. Coins not intended for circulation or for intrinsic value have also been made experimentally using an even larger variety of metals, since they function as fiat money. In general coins intended for circulation must have metal values considerably less than their face values, for reasons discussed below.
Coins that are intended for circulation have some special requirements based on the conditions they will encounter. For example, a coin may be in circulation for up to 30 years, and so must have excellent wear resistance and anti-corrosion properties. Achieving this goal necessitates the use of base metal alloys. Some metals like manganese have occasionally been used in coins, but suffer from making the coins too hard to take an impression well (or metals apt to wear out stamping machines at the mint).
When minting coins, especially low denomination coins, there is a risk that the value of metal within a coin is greater than the face value. This leads to the possibility of smelters taking coins and melting them down for the scrap value of the metal. Pre-1992 British pennies were made of 97% copper; but as of 2008, based on the price of copper, the value of a penny from this period is 1.5 new-pence. Modern British pennies are now made of copper-plated steel. For similar reasons, American pennies (cents) were once made of copper alloys, but since 1982 have been made of copper-plated zinc.
This problem has led to nearly the end of use for a common base metal alloy for everyday coinage in the 20th century, called cupronickel, with varying proportions of copper and nickel, most commonly 75% Cu 25% Ni. Cupronickel has a silver color, is hard wearing and has excellent striking properties, essential for the design of the coin to be pressed accurately and quickly during manufacture. In the 21st century with the prices of both copper and nickel rising, it has become more common to experiment with various alloys of steel, often stainless steel. For example, in India some coins have been made from a stainless steel that contains 82% iron, 18% chromium, and many other countries that have minted coins that contain metals now worth nearly the coin face-value, are experimenting with various steel alloys.
Chemical elements used in non-circulating (commemorative, demo or novelty) coins, medals, patterns, and trial strikes:
Beginning in 2006, Dave Hamric (Metallium) has been attempting to strike "coins" (technically tokens or medals, about the size of a US cent) of every primordial chemical element (hydrogen through bismuth, excluding the radioactive technetium and promethium, but including the long-lived thorium and uranium). To date he has struck tokens of the following elements:
World Coin News magazine published an article titled "World's Coinage Uses 24 Chemical Elements" by Jay and Marieli, which appeared in two consecutive issues: Feb. 17, 1992, pages 24–25; and Mar. 2, 1992, pages 18–19.
The article was based on an award-winning exhibit that was assembled by Jay and Marieli Roe (a.k.a. Dr. John Westel Rowe, an organic chemist in Wisconsin, and his wife Marieli Rowe), and shown during the 1987–1990 period. The 24 elements named are: Al, Sb, C, Co, Cu, Au, Hf, Fe, Pb, Mg, Mo, Ni, Nb, Pd, Pt, Re, Ag, Ta, Sn, Ti, W, V, Zn and Zr.
The ANA did not award Best-of-Show "because the exhibit was downgraded for incompleteness" due to two missing pieces. However, the author defended his choices: The British Royal Mint's rhodium token "is only rhodium-plated", and the Pobjoy Mint's iridium coin "does not exist (possible confusion with palladium?)."
Curiously, chromium and manganese were not mentioned, even though both elements had been used in common circulation coins (Canada wartime V nickels and US wartime Jefferson nickels, respectively) long before the time of the article's publication.
|Material||Example of usage|
|Paper||Paper 50 kopecks (1923, Soviet Russia)|
|Wood||Used for coin-like tokens, such as wooden nickel|
|Stone||Rai stones from Yap island|
|Cardboard||Cardboard, 15 kopecks (1915, Russian Empire)|
|Ceramics||75 pfennig, notgeld, Zielona Gora, 1922|
|Leather||Leather rubles of the Russian-American Company in Alaska|
|Plastic||Transnistrian ruble coins|
|Compressed charcoal||1000 mark private notgeld, Conradty Company, 1922)|
|Porcelain||Notgeld produced in 1920—1921 at the Meissen Porcelain Works|
|Fiber||1 and 5 fen coins, Manchukuo, 1944-45 .|
|Silk||Khorezmian silk money|
Acmonital (Acciaio Monetale Italiano or Italian monetary steel) is a stainless steel alloy consisting mostly of iron, with 0.14% carbon, 17.5-19% chromium, 0.50% magnesium, 1.15% silicium, 0.03% sulfur, and 0.03% phosphorus by weight. Acmonital was used for the Italian Lira coins.Alternative periodic tables
Alternative periodic tables are tabulations of chemical elements differing significantly in their organization from the traditional depiction of the periodic system. Several have been devised, often purely for didactic reasons, as not all correlations between the chemical elements are effectively captured by the standard periodic table.
Alternative periodic tables are developed often to highlight or emphasize different chemical or physical properties of the elements which are not as apparent in traditional periodic tables. Some tables aim to emphasize both the nucleon and electronic structure of atoms. This can be done by changing the spatial relationship or representation each element has with respect to another element in the table. Other tables aim to emphasize the chemical element isolations by humans over time.Arsenical bronze
Arsenical bronze is an alloy in which arsenic, as opposed to or in addition to tin or other constituent metals, is added to copper to make bronze. The use of arsenic with copper, either as the secondary constituent or with another component such as tin, results in a stronger final product and better casting behaviour.Copper ore is often naturally contaminated with arsenic; hence, the term "arsenical bronze" when used in archaeology is typically only applied to alloys with an arsenic content higher than 1% by weight, in order to distinguish it from potentially accidental additions of arsenic.Arsenical copper
Arsenical copper contains up to 0.5% arsenic which, at elevated temperatures, imparts higher tensile strength and a reduced tendency to scaling. It is typically specified in boiler work, especially locomotive fireboxes. It also helps prevent embrittlement of oxygen free copper by bismuth, antimony and lead by the formation of complex oxides. Copper with a larger percentage of arsenic is called arsenical bronze, which can be work-hardened much harder than copper.Coin
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 are usually metal or 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 (i.e. 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.Cupronickel
Cupronickel or copper-nickel (CuNi) is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. The copper contents typically varies from 60 to 90 percent. (Monel metal is a nickel-copper alloy that contains a minimum of 52 percent nickel.)
Despite its high copper content, cupronickel is silver in colour. Cupronickel is highly resistant to corrosion by salt water, and is therefore used for piping, heat exchangers and condensers in seawater systems, as well as for marine hardware. It is sometimes used for the propellers, propeller shafts, and hulls of high-quality boats. Other uses include military equipment and chemical, petrochemical, and electrical industries.Another common modern use of cupronickel is silver-coloured coins. For this use, the typical alloy has 3:1 copper to nickel ratio, with very small amounts of manganese. In the past, true silver coins were debased with cupronickel.Electrum
Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. It has also been produced artificially, and is often known as green gold. The ancient Greeks called it 'gold' or 'white gold', as opposed to 'refined gold'. Its colour ranges from pale to bright yellow, depending on the proportions of gold and silver.
The gold content of naturally occurring electrum in modern Western Anatolia ranges from 70% to 90%, in contrast to the 45–55% of gold in electrum used in ancient Lydian coinage of the same geographical area. This suggests that one reason for the invention of coinage in that area was to increase the profits from seigniorage by issuing currency with a lower gold content than the commonly circulating metal. (See also debasement.)
Electrum was used as early as the third millennium BCE in Old Kingdom of Egypt, sometimes as an exterior coating to the pyramidions atop ancient Egyptian pyramids and obelisks. It was also used in the making of ancient drinking vessels. The first metal coins ever made were of electrum and date back to the end of the 7th century or the beginning of the 6th century BCE. For several decades, the medals awarded with the Nobel Prize have been made of gold-plated green gold.Group (periodic table)
In chemistry, a group (also known as a family) is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table, and the f-block columns (between groups 3 and 4) are not numbered. The elements in a group have similar physical or chemical characteristics of the outermost electron shells of their atoms (i.e., the same core charge), as most chemical properties are dominated by the orbital location of the outermost electron.
There are three systems of group numbering for the groups, that often assign the same number to different groups. The modern numbering "group 1" to "group 18" has been recommended by the International Union of Pure and Applied Chemistry (IUPAC) since about 1990. It replaces two older incompatible naming schemes, used by the Chemical Abstract Service (CAS, more popular in the U. S.), and by IUPAC before 1990 (more popular in Europe).
Groups may also be identified by their topmost element or have a specific name. For example, group 16 is variously described as the "oxygen group" and as the "chalcogens". However, iron group usually does not mean "group 8". In chemistry it may mean either iron, cobalt, and nickel, or some other set of elements with similar chemical properties. In astrophysics and nuclear physics, it usually means those three plus chromium and manganese.Group 11 element
Group 11, by modern IUPAC numbering, is a group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), and gold (Au). Roentgenium (Rg) is also placed in this group in the periodic table, although no chemical experiments have yet been carried out to confirm that it behaves like the heavier homologue to gold. Group 11 is also known as the coinage metals, due to their former usage. They were most likely the first three elements discovered. Copper, silver, and gold all occur naturally in elemental form.Italma
Italma (acronym of Italiano Alluminio Magnesio) is an aluminium alloy. It was produced by A.S.A. (Alluminio Soc. Anonima) and was introduced shortly after World War II in order to being used in the new coinage of the Italian lira, which lasted until the adoption of the Italian euro coins in 2002. It comprised 96.2% aluminium, 3.5% magnesium, and 0.3% manganese.Light metal
A light metal is any metal of relatively low density. More specific definitions have been proposed; none have obtained widespread acceptance. Magnesium, aluminium and titanium are light metals of significant commercial importance. Their densities of 1.7, 2.7 and 4.5 g/cm3 range from 19 to 56% of the densities of the older structural metals, iron (7.9) and copper (8.9).Melchior (alloy)
In metallurgy, melchior is an alloy of copper, mainly with nickel (5–30%). Its name originates from Italian: melchior, which in turn is distorted French: maillechort, honoring the French inventors of the alloy, Maillot and Chorier. The term melchior sometimes refers not only to the copper-nickel alloys, but also ternary alloys of copper with nickel and zinc ("nickel silver") and even a silvered brass. Melchior is easily deformable by application of pressure, both in the hot and cold state. After annealing, it has a tensile strength of about 40 kg/mm2. The most valuable property of melchior is its high resistance to corrosion in air, freshwater and seawater. Increasing content of nickel iron or manganese improves corrosion and cavitation resistance, especially in sea water and atmospheric water vapor. The alloy of 30% Ni, 0.8% Fe, 1% Mn and 68.2% copper is used in maritime shipping, in particular for the manufacture of condenser tubes. Thanks to the nickel, melchior, unlike brass and bronze, has not a yellow but a silver color. Together with high corrosion resistance, this silvery color is preferred for the manufacture of household utensils.Metal
A metal (from Greek μέταλλον métallon, "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typically malleable (they can be hammered into thin sheets) or ductile (can be drawn into wires). A metal may be a chemical element such as iron, or an alloy such as stainless steel.
In physics, a metal is generally regarded as any substance capable of conducting electricity at a temperature of absolute zero. Many elements and compounds that are not normally classified as metals become metallic under high pressures. For example, the nonmetal iodine gradually becomes a metal at a pressure of between 40 and 170 thousand times atmospheric pressure. Equally, some materials regarded as metals can become nonmetals. Sodium, for example, becomes a nonmetal at pressure of just under two million times atmospheric pressure.
In chemistry, two elements that would otherwise qualify (in physics) as brittle metals—arsenic and antimony—are commonly instead recognised as metalloids, on account of their predominately non-metallic chemistry. Around 95 of the 118 elements in the periodic table are metals (or are likely to be such). The number is inexact as the boundaries between metals, nonmetals, and metalloids fluctuate slightly due to a lack of universally accepted definitions of the categories involved.
In astrophysics the term "metal" is cast more widely to refer to all chemical elements in a star that are heavier than the lightest two, hydrogen and helium, and not just traditional metals. A star fuses lighter atoms, mostly hydrogen and helium, into heavier atoms over its lifetime. Used in that sense, the metallicity of an astronomical object is the proportion of its matter made up of the heavier chemical elements.Metals comprise 25% of the Earth's crust and are present in many aspects of modern life. The strength and resilience of some metals has led to their frequent use in, for example, high-rise building and bridge construction, as well as most vehicles, many home appliances, tools, pipes, and railroad tracks. Precious metals were historically used as coinage, but in the modern era, coinage metals have extended to at least 23 of the chemical elements.The history of metals is thought to begin with the use of copper about 11,000 years ago. Gold, silver, iron (as meteoric iron), lead, and brass were likewise in use before the first known appearance of bronze in the 5th millennium BCE. Subsequent developments include the production of early forms of steel; the discovery of sodium—the first light metal—in 1809; the rise of modern alloy steels; and, since the end of World War II, the development of more sophisticated alloys.Names for sets of chemical elements
There are currently 118 known chemical elements exhibiting a large number of different physical and chemical properties. Amongst this diversity, scientists have found it useful to use names for various sets of elements, that illustrate similar properties, or their trends of properties. Many of these sets are formally recognized by the standards body IUPAC.The following collective names are recommended by IUPAC:
Alkali metals – The metals of group 1: Li, Na, K, Rb, Cs, Fr.
Alkaline earth metals – The metals of group 2: Be, Mg, Ca, Sr, Ba, Ra.
Pnictogens – The elements of group 15: N, P, As, Sb, Bi. (Mc had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.)
Chalcogens – The elements of group 16: O, S, Se, Te, Po. (Lv had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.)
Halogens – The elements of group 17: F, Cl, Br, I, At. (Ts had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.)
Noble gases – The elements of group 18: He, Ne, Ar, Kr, Xe, Rn. (Og had not yet been named when the 2005 IUPAC Red Book was published, and its chemical properties are not yet experimentally known.)
Lanthanoids – Elements 57–71: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.
Actinoids – Elements 89–103: Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr.
Rare-earth metals – Sc, Y, plus the lanthanoids.
Transition elements – Elements in groups 3 to 11 or 3 to 12.Another common classification is by degree of metallic – metalloidal – nonmetallic behaviour and characteristics. There is no general agreement on the name to use for these sets: in this English Wikipedia, the name used is "category". Very often these categories are marked by a background color in the periodic table. Category names used here, without any claim to universality, are:
Alkali metals, alkaline earth metals, and noble gases: Same as the IUPAC system above.
Transition elements are instead referred to as transition metals.
Lanthanoids and actinoids are instead referred to as lanthanides and actinides respectively.
Rare-earth elements, pnictogens, chalcogens, and halogens are not used as category names, but the latter three are valid as group (column) names.
Additional element category names used:
Post-transition metals – The metals of groups 12–17: Zn, Cd, Hg, Al, Ga, In, Tl, Sn, Pb, Bi, Po. The period 7 elements Nh, Fl, Mc, Lv, and Ts are additionally predicted to be post-transition metals.
Metalloids – Elements with properties intermediate between metals and non-metals: B, Si, Ge, As, Sb, Te, At.
Reactive nonmetals – Nonmetals that are chemically active (as opposed to noble gases): H, C, N, P, O, S, Se, F, Cl, Br, I
Superactinides – Hypothetical series of elements 121 to 157, which includes a predicted "g-block" of the periodic table.Many other names for sets of elements are in common use, and yet others have been used throughout history. These sets usually do not aim to cover the whole periodic table (as for example period does). Some examples:
Precious metals – Variously-defined group of non-radioactive metals of high economical value.
Coinage metals – Various metals used to mint coins, primarily the group 11 elements Cu, Ag, and Au.
Platinum group – Ru, Rh, Pd, Os, Ir, Pt.
Noble metal – Variously-defined group of metals that are generally resistant to corrosion. Usually includes Ag, Au, and the platinum-group metals.
Heavy metals – Variously-defined group of metals, on the base of their density, atomic number, or toxicity.
Native metals – Metals that occur pure in nature, including the noble metals and others such as Sn and Pb.
Earth metal – Old historic term, usually referred to the metals of groups 3 and 13, although sometimes others such as beryllium and chromium are included as well.
Transuranium elements – Elements with atomic number greater than 92.
Transactinide elements – Elements after the actinides (atomic number greater than 103).
Transplutonium elements – Elements with atomic number greater than 94.
Minor actinides – Actinides found in significant quantities in nuclear fuel, other than U and Pu: Np, Am, Cm.
Heavy atom – term used in computational chemistry to refer to any element other than hydrogen and helium.Nordic Gold
Nordic gold is the gold-coloured copper alloy from which the middle three denominations of euro coins (50, 20, and 10 cents) are made. It has also been in use for a number of years in other countries, most notably in the Swedish 5- and 10-kronor coins, the latter of which it was originally developed for (hence the Swedish name: nordiskt guld), as well as the Polish 2 złote commemorative coins. Its composition is 89% copper, 5% aluminium, 5% zinc, and 1% tin.Being a brass alloy, it contains no gold and its colour and weight are quite unlike pure gold. It is non-allergenic; its other advantages include antimycotic and weak antimicrobial (especially after abrasion) attributes, and resistance to tarnishing.Potin
Potin (also known as billon) is a base metal silver-like alloy used in coins. It is typically a mixture of copper, tin and lead (in varying proportions) and it is debated whether any actual silver needs to be present. While the term billon is more commonly applied to ancient Roman coinage, potin is usually used for Greek or Celtic coinage.Precious metal
A precious metal is a rare, naturally occurring metallic chemical element of high economic value.
Chemically, the precious metals tend to be less reactive than most elements (see noble metal). They are usually ductile and have a high lustre. Historically, precious metals were important as currency but are now regarded mainly as investment and industrial commodities. Gold, silver, platinum, and palladium each have an ISO 4217 currency code.
The best known precious metals are the coinage metals, which are gold and silver. Although both have industrial uses, they are better known for their uses in art, jewelry, and coinage. Other precious metals include the platinum group metals: ruthenium, rhodium, palladium, osmium, iridium, and platinum, of which platinum is the most widely traded.
The demand for precious metals is driven not only by their practical use but also by their role as investments and a store of value. Historically, precious metals have commanded much higher prices than common industrial metals.Sterling silver
Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.
Fine silver, for example 99.9% pure silver, is relatively soft, so silver is usually alloyed with copper to increase its hardness and strength. Sterling silver is prone to tarnishing, and elements other than copper can be used in alloys to reduce tarnishing, as well as casting porosity and firescale. Such elements include germanium, zinc, platinum, silicon, and boron. Recent examples of alloys using these metals include argentium, sterlium, sterilite and silvadium.Systematic element name
A systematic element name is the temporary name assigned to a newly synthesized or not yet synthesized chemical element. A systematic symbol is also derived from this name. In chemistry, a transuranic element receives a permanent name and symbol only after its synthesis has been confirmed. In some cases, such as the Transfermium Wars, controversies over the formal name and symbol have been protracted and highly political. In order to discuss such elements without ambiguity, the International Union of Pure and Applied Chemistry (IUPAC) uses a set of rules to assign a temporary systematic name and symbol to each such element. This approach to naming originated in the successful development of regular rules for the naming of organic compounds.