This page details the various metals and alloys that have been used for coins and medals over the centuries.
When I was at University I gave a talk to the college Science Society on the subject, and it is also of interest to me as my first job involved carrying out research into alloys of such exotic materials as niobium, hafnium, tantalum, zirconium and titanium for superconducting, chemical and aeronautical applications.
We also had some gallium, but somebody left it above a radiator and it melted!
Some (but by no means all) of the information came out of 'The Teach Yourself Guide to Numismatics' by C.C.Chamberlain published in 1960, and I also wish to acknowledge the help of many correspondents on the newsgroup rec.collecting.coins; they are too numerous to mention individually.
Additional information has been gleaned from an article published in World Coin News (February 17 1992 and March 2 1992) entitled 'World's coinage uses 24 chemical elements' by Jay and Marieli.
The following materials are covered in this document:
The metal was first prepared by Oersted in 1825 and Wohler in 1827, although Humphry Davy decomposed alumina to form an aluminium-iron alloy in about 1808.
A very 'white' corrosion resistant metal used for cheap coins in a number of countries, particularly in Europe where inflation had decreased the value of money. Recent examples include the tiny 1 peseta coin issued by Spain, and the 5 and 10 lire coins of Italy.
The pure metal is very soft, and so does not wear well. Sometimes magnesium is used to harden it and improve corrosion resistance.
In addition, aluminium is used as an important alloying addition (see Aluminium Bronze).
There is an apocryphal story that the absence of the second letter i in the American spelling was the consequence of a signwriter misspelling the word when the first producer of aluminium started up in the US! After all, the Americans don't use the words sodum, potassum, chromum or titanum, do they? However, I gather that this tale is an urban legend!
Copper-aluminium alloys, with 5-11% aluminium as the main alloying addition, sometimes containing a small amount of manganese or nickel. They are yellow in colour and hard wearing. A modern example of its use is with the 5, 10 and 20 centime coins of France.
A variety called Nordic Gold has been used for some Scandinavian coins, and also for the new 10, 20 and 50 eurocent coins because it does not contain nickel. It has a composition of 89% Cu, 5% Al, 5% Zn and 1% Sn.
Aluminium Bronzes are popular as a coinage material as they are more corrosion resistant than bronze, and have a distinctive colour.
Known since ancient times.
A silvery metal which is very brittle, and is easily crushed and powdered, and is thus an unlikely candidate for use in coins. It is easily cast (melting at 631°C), and gives a clear impression of the mould. Its main use is as an alloying addition used to harden lead.
The only example of which I am aware of the use of antimony for an issued coin is a 10c piece struck(?) in China in 1931.
A pattern in this metal of a penny, struck in 1860, has recently been put on sale by Spinks of London.
It is used alloyed with tin, copper or lead to produce white metal used in the manufacture of medallions.
Barton's Metal is in fact copper overlaid with a thick layer of gold, and was used in 1825 during the reign of George IV for pattern five pound and two pound coins by the Royal Mint.
A type of cheap bronze used in the manufacture of some Irish and American tokens, and for some coins of the Isle of man. As a copper-zinc alloy (about 19% Zn) it is technically a brass. Also known as Pinchbeck.
A type of high tin bronze (around 22% tin) normally used in the manufacture of bells, but also used in France at the time of the Revolution. Generally too brittle for coinage use.
An alloy of copper and silver, with more than half copper. Large quantities of billon coins were produced in the Roman era, many with a silver wash, and in mediaeval times throughout Europe. This alloy was also used by the French during the 18th century.
An alloy of copper and zinc, although the term is loosely used to include all copper alloys. Generally the alloys used vary in composition from 3% zinc to 30% zinc, and vary in colour from the red of copper to a bright yellow.
Brass with a small quantity of nickel is known as Nickel Brass. Such alloys are used for the modern UK one pound coin.
The Roman name for the brass alloy used in coins was Orichalchum
In Old English the Latin word aes was rendered as brass, thus the use of the word brass to mean money still found today, especially in Northern England. Many brass coins have been produced in modern times, although more complex copper alloys are normally used.
Various forms of brass have been used to make fake gold coins to deceive gullible collectors (the density is totally wrong), and I have been informed that a brass with 15% zinc is sometimes known as Goldine in the USA.
An alloy of copper and tin, usually 80% to 95% copper. Most modern 'copper' coins are actually bronze, as pure copper is too soft and rapidly shows extensive wear. While bronze is usually copper coloured, a high tin content will give a silver colour, as in speculum.
As the price of copper has risen, so bronze is often being replaced by a copper clad metal of lower value. Examples are the copper-clad steel of UK one and two penny coins, and copper-clad zinc used for US one cent coins.
Bell Metal and Bath Metal are other types of bronze.
First isolated in 1798 by Vauquelin.
A hard white metal which is unsuitable for coinage, but which has been used to plate steel coins. An example of such use is the Canadian 5c pieces of 1944-45 and 1951-1954, which were nickel-plated steel with a surface plating of chromium to add wear resistance. A few medals have been struck in chromium.
Chromium is an important constituent of the alloy Stainless Steel and is also used in smaller concentrations to impart hardness to steels. It is not usually used in its pure form as it has too high a melting point to cast easily, and is too hard to work.
First isolated in 1733 by Brandt.
A steel-grey metal with a reddish tinge which is strongly magnetic. It is normally used as an alloying addition. 35 medals were made in this metal for a conference on cobalt, and are thought to be the only examples of this element's use in the pure form.
I gather that there is a Cameroon coin that has been coated in cobalt.
A soft reddish metal known since ancient times. It is rarely used unalloyed in modern coins, other than as a coating for other metals (modern US cents and the UK 1p and 2p are examples), because it has relatively poor wear properties. The beautiful large British pennies of Queen Victoria from 1839 to 1859 were made of copper.
One of the largest conventional copper coins that ever circulated is the Cartwheel twopence of 1797 produced by Matthew Boulton at the Soho Mint in Birmingham. Swedish plate money issued from 1644 to 1759 consisted of large lumps of copper cut roughly into squares weighing up to 6 pounds (3 kg) and 10 in (25 cm) across. They were issued because of a grave shortage of silver after a war with Denmark. I bet they wore holes in Swedish pockets!
It is the main constituent of a wide range of alloys such as aluminium bronze, brass, bronze, cupro-nickel, gun metal, Orichalchum, and Pinchbeck.
Gold with 2 carats of alloy and 22 carats of gold so called from the gold crown of 1526 which used this alloy. Previously gold coins were made from almost pure gold. Crown gold is the standard used in the British sovereign which is still minted. The alloying metal is usually copper, although silver has been used.
Self-evidently an alloy of copper and nickel, it is one of the most common alloys used in modern coins. It is also called copper-nickel in the US by some. A related alloy called Alpaca also contains zinc.
It is silvery in appearance and hard wearing, and yet easy to fabricate. In the UK was first used in 1947 where an alloy of 75% Cu and 25% Ni is used for most 'silver' coins. With this composition the coin shows no trace of the colour of its main constituent.
Other copper-nickel alloys have been used. The early US cents from 1857 to 1864 contain 87.5% Cu and 12.5% Ni, and so have a light yellow colour, while the present-day 20p coin of the UK is made from an 84% Cu and 16% Ni alloy. Some modern cupro-nickel coins of Russia also contain zinc. The Franklin Mint in the USA have developed a cupro-nickel alloy they call Franklinium. Bactrian coins of King Euthydemus (220 BC) are known in a copper-nickel alloy. The origin of the nickel in these coins is uncertain.
This naturally occurring alloy of approximately 75% gold with 25% silver and copper and other metals was used for the earliest coins struck in Lydia around 700 BC. The name electrum is also used for an artificial alloy such as used for coins in the Merovingian Dynasty of the Kingdom of the Franks around 600 - 700 AD.
It might be argued that coins made at private mints in the US from native gold at the time of the gold rush in California are made from electrum.
Gold is the most anciently known of metals, occurring as the native metal.
Perhaps the most ideal metal for coins, as it is malleable and chemically inert, to the extent that gold coins discovered after long periods in the ground still maintain their lustrous appearance. As it is a soft metal it is nowadays almost always used alloyed with copper to make it more durable, although gold-silver alloys have been used, particularly by Australia in the manufacture of sovereigns and half-sovereigns during the period 1855-1870.
At present the only gold coins minted are for bullion purposes, guaranteeing fineness and weight.
Early english coins were made of pure gold, but a number of other alloys have been used, examples including Crown Gold and Electrum.
An alloy of 88 % copper, 10% tin and 2% zinc, used for making cannons. Not normally used for coins, although the famous Gun Money was produced from 1689 by James II for use in Ireland. It was cast in scrap metal from old cannons, bells, etc., and is unusual in having the month as well as the year of issue indicated. Imagine collecting Lincoln cents from 1909 to date if there were 12 different coins per year (or more if you include mint mark variations)!
First isolated as recently as 1923 by Coster and Hevesy.
Fred Zinkann has struck a few private pattern 'coins' in this metal, which has few uses except in the nuclear industry, where its high neutron capture cross-section makes it useful for control rods in some nuclear reactors.
Hafnium is chemically very similar to zirconium with which it is normally found in nature. Indeed, zirconium ores always contain hafnium in a proportion of between 0.7% and 50%.
As mentioned above, hafnium absorbs neutrons very readily, whereas zirconium does not. The need to remove hafnium from zirconium for nuclear applications is one reason for the high cost of the latter material.
First isolated in prehistoric times, for many years iron was not used as currency as it was heavy, brittle in the most commonly available cast form, and liable to rust.
(Before someone tells me that copper and gold are denser, I mean heavy in terms of its weight per unit value.)
Cast iron contains between 3% and 4.2% C, melting at between 1150°C and 1250°C, depending on the carbon content. Iron alloys containing small levels of carbon are normally called steel.
Iron coins were issued by Finland between 1943 and 1953, and also Bulgaria in 1943.
To get round the corrosion problem in modern coins various coatings have been used, from copper (modern UK 'coppers') and brass (German 5 and 10 pfennig) to nickel and chromium (Canadian post-war 5 cents), nickel alone (Finnish 1 & 5 markaa 1953-1962) or zinc (US cent of 1943). Some of these have actually got a steel rather than iron core.
A medal has been made from the "Campo del Cielo" meteorite, which was of an iron-nickel composition.
Lead is a very soft bluish-grey metal, and so early lead coins do not survive too well. However, it has been used, particularly in southern India around the time of Christ, in China, and in Burma and Siam during the 19th century. Because it casts well and has a silvery appearance when new it has often been used for forgeries, especially when plated to replicate gold coins.
In Roman times lead was used for tesserae, which were tickets or tokens (also made in bronze) that were distributed by the emperor (amongst others) entitling the holder to either food or money.
In its normal state it tarnishes rapidly to a dark grey colour, and has extremely poor wear resistance.
First isolated as a metal by Davy in 1808.
Magnesium is a silver-white ductile metal 40% lighter than aluminium. It is an important alloying addition in many metallurgical applications, and it is used in an aluminium-magnesium alloy for recent coins of India. The addition of magnesium improves the hardness and corrosion resistance of aluminium.
There have been some minor issues - the Jay and Marieli article refers to a 10 pfennig Lodz Ghetto issue.
The Dow Chemical Company struck some tokens in Dowmetal, an alloy of this metal with about 6% Al and ½% Mn, in 1933.
First isolated by Gahn in 1774.
A grey metal resembling polished steel. It is not used as a pure metal in coins or medals because it reacts with water, but often found in alloys. The WWII 5c pieces of the USA were made from a 56%Cu 35%Ag 9%Mn alloy from 1942 to 1945 as nickel is a vital material in war. I am grateful to Louis S. Flocco of the USA for the information that this alloy was chosen in order to match the electrical properties of the original cupronickel alloy so that it could be used in pay telephones and other vending machines.
Technically a nickel brass containing an additional amount of manganese. It is a copper alloy containing zinc, manganese and a small quantity of nickel which is used for the new US dollar. The composition used for the dollar is 88.5% Cu, 6% Zn, 3.5% Mn and 2% Ni overall, with a cladding of 77% Cu, 12% Zn, 7% Mn and 4% Ni. This combination was chosen in order to match the electrical properties of the earlier Susan B. Anthony dollar to avoid costly changes to vending machines.
First isolated in 1781 by Hjelm.
An silvery-white element usually used as an alloying addition to steels and titanium alloys, although there are applications where the pure metal is used. It has not been used for circulation coins, although a small number of patterns have been made in this metal by Fred Zinkann.
First isolated in 1751 by Cronstedt, an event commemorated by Canada in 1951 with a special 5c piece. However, the element is present in alloy form in early Bactrian coins dating from about 200 BC.
Usually used in an alloy with copper (see cupro-nickel) or iron (see stainless steel), although the pure metal has been (and is) used a great deal, notably for the coins of Switzerland and Canada. It was first used in this form by Switzerland in 1881. The pure metal is magnetic, and is noticeably yellower than some of the silvery metals such as chromium and aluminium.
In 1965 the United States produced pattern coins in a 95% nickel 5% silicon alloy, but it appears that all specimens were melted down. More recently UK 5p and 10p coins have been issued in steel with nickel plating.
There is some concern that a number of people are allergic to nickel, thus the avoidance of this element in alloys used for the new euro coins.
A copper alloy containing zinc and a small quantity of nickel which is used for the UK 'brass' threepenny bit and the pound coin. The composition used for the threepenny bit was 79% Cu, 20% Zn and 1% Ni, while that for the pound coin and early single metal two pound coins is 70% Cu, 24.5% Zn and 5.5% Ni. The outer ring of the bimetallic two pound coin is 76% Cu, 20% Zn and 4% Ni.
A copper alloy containing 18-22% nickel, 15-20% zinc and sometimes manganese and other metals which is made with a wide variety of compositions.
The alloy is sometimes known as German Silver or Argentan. One variety of nickel silver is an alloy of 70% copper, 15% nickel and 15% zinc used in Peru and Chile and known locally as Alpaca.
First isolated in 1801 by Hatchett.
An expensive grey metal mainly used for superconducting applications in alloy form. The occasional medal has been made using this metal. This element used to be called Columbium (symbol Cb) in the USA.
Trials using this metal have been carried out at the Sherritt Mint in Canada, and at the Philadelphia Mint in the USA.
Austria has issued a number of bimetallic 25 euro coins with a niobium centre. The niobium centres are coloured by anodising - making the coin the anode in an electrolyte which build up a thin oxide film that is coloured by interference effects. The colour depends on the oxide thickness which in turn depends on the voltage used. This is similar to the same type of effect used with titanium.
A word used by the Romans to denote their brass, containing 80% copper and 20% zinc, approximately. The dupondius was distinguished from the as by being in orichalchum rather than copper, as well as by having the emperor with a radiate crown, whereas the sestertius, also in orichalchum, was larger. (1 dupondius = 2 asses, 1 sestertius = 4 asses, 1 denarius = 16 asses)
First isolated and identified as an element in 1803 by Wollaston, but artifacts containing palladium alloyed with platinum date from earlier times.
An interesting history of palladium is to be found at the Stillwater palladium website.
A scarce ductile metal of the platinum series which does not have quite the same economic importance of platinum at present. Some bullion coins have been made of this metal, the first being the 1967 ½ Hau from Tonga which was actually an alloy containing 2% ruthenium. The metal work-hardens quickly which makes striking coins more difficult than silver or gold. Northwest Territorial Mint (amongst others) strike bullion rounds in this metal.
Originally an alloy of tin with about 15% lead, and sometimes antimony and copper. Modern pewters are usually lead-free.
Pewter coins include the 1757 1 and 3 kreuzer of Bohemia struck during the siege of Prague, and a 5 franc French piece of 1831.
A cheap brass, mainly copper with some zinc, invented in the 18th century as a cheap imitation of gold. Also known as Bath Metal, it was used for medals rather than coins.
Now known as Gilding Metal.
First isolated in 1735 by De Ulloa.
Discovered in quantity in Russia in about 1822, and used by that country during the period 1828 to 1835 for coins. Platinum is the most common of the platinum group of metals, and is ductile, making it relatively easy to make into coins. However, supplies are relatively limited, and the metal has a far more important use as a catalyst in chemical reactions.
It is seen as a bullion metal as well as an important metal for chemical applications, and a number of bullion coins have been struck.
One of the earliest uses of platinum for medals was in France during the Napoleonic period around 1800. I am indebted to David Block of the USA for this information.
An ancient alloy of copper, zinc, lead and tin found in coins of Ancient Gaul. Unlike billon, it normally contains no silver, although some alloys containing silver have also been called potin, such as some from Egypt in the 1st to 3rd century A.D.
Apparently this alloy was also used in 1st century coins from southern India.
First isolated in 1925 by Noddack, Tack and Berg.
Fred Zinkann has struck a fantasy coin in this very scarce white metal.
An attractive white metal extensively used for coins from ancient times to the present day, although the increasing value of the metal has meant that few countries now use it except for proof specimens. It is harder than gold, but is easily worked. Unlike gold, it tarnishes readily if there is sulphur in the atmosphere. It recent times is was normally used in alloy form.
Mexico issues composite coins with a .925 silver centre. As far as I am aware this is the only country using silver for circulation coins.
A large number of silver alloys have been used over the years. A silver-lead alloy has been used in Bhutan.
Sterling silver (92.5% Ag) is usually alloyed with copper. This alloy was used for British silver coins up until 1920.
During 1920 the silver content was reduced to 50%, with 40% Cu and 10% Ni. It was found that this alloy tarnished badly, going an unattractive yellow-brown colour, so the alloy was changed to 50% Ag with 50% Cu. This in turn was changed to 50% Ag, 40% Cu, 5% Ni and 5% Zn in 1927, with a significant improvement in appearance.
A silvery alloy of tin and bronze used in Gaul and Britain during the period around the time of Caesar's invasion.
A hard-wearing alloy of iron, chromium and nickel. The 50 and 100 lire coins of Italy use this material. Because it is a hard material, and thus fairly difficult to strike, you usually find that stainless steel coins have a fairly low relief.
The alloy used by Italy is sometimes known as Acmonital, an acronym for Aciaio Monetario Italiano
A general name given to iron-carbon alloys having smaller amounts of carbon than cast iron. Strictly speaking most modern iron coins are made of steel. Steel rusts very readily so it needs a coating when used for coins.
Nickel and copper clad steel coins were in use in Bolivia from 1965 to 1987, when hyper-inflation led to a new series of stainless steel coins.
Zinc coated steel was used for 2 Franc coins during the Allied Occupation of Belgium in 1944. They were made from the same blanks as the zinc coated steel US 1 cent piece of 1943.
The 'bronze' coinage of the UK has been copper-clad steel since 1992, with a couple of minor exceptions.
First isolated in 1802 by Ekeberg.
A hard blue-coloured metal with a very high melting point. Too expensive and difficult to work for regular coinage, but once again Fred Zinkann has made a medal in this material.
Some fantasy coins for the Islas Malvinas (Falkland Islands) are known, as is a bimetallic silver-tantalum coin from Kazakhstan.
First isolated in 1783 by Muller.
A hard grey semi-metal, or metalloid, similar to selenium but not used for coinage. However, in an alloy with 11% copper it has been used for a commemorative medal. This may be the 1896 medal from Hungary that has been reported; it is possible that the latter was made from 'pure' tellurium.
Silver-like in colour and very malleable, but too soft to stand up to wear, and the metal is more often used as an alloying addition in copper to make bronze.
One such alloy, known as speculum, was used by the Belgic people of Gaul and Southern Britain during the two centuries before the birth of Christ.
Farthings and halfpennies were struck in tin with a central copper plug in England during the 17th century. The intention was to try and deter forgers, but the experiment was not a success.
The metal has two (or perhaps three) allotropic forms:
Thus on an ordinary English winter day white tin should turn into a grey powder. In fact this does not happen unless in extreme cold, but once some is formed, the transformation is more rapid, giving rise to what is known as tin-pest. I have heard it said that Napoleon's troops invading Russia in 1812 had tin buttons holding their trousers up, with disastrous consequences when winter set in!
Tin was used for coins in Thailand in the mid 1940's, but then the temperature does not fall so low there. Japan used a tin-zinc alloy in 1944.
When a rod of tin is bent, it emits a characteristic noise known as the 'Cry of Tin'. However, this phenomena has also been observed with other elements, particularly cadmium.
First isolated in 1791 by Gregor.
Titanium is a strong light metal that is corrosion resistant. It could be used for coins, and has been used to strike medals. However, there are problems in producing a sheet of the metal with a smooth enough surface for coinage purposes, and this increases the cost of producing coins in bulk using this metal. As the basic cost of the raw metal is high as well, other cheaper alternatives are more attractive to governments!
I have a few tokens struck in this metal during trials at Imperial Metal Industries Ltd. Birmingham during the late 60's.
Apparently a new zinc-titanium alloy has been developed for coinage, but no information as to its use is available. Austria has made bimetallic commemorative coins of silver and titanium.
Tombac is a brass alloy famous in numismatic circles for its use by Canada in the emergency 5 cent coins of 1942 and 1943, but more generally known for its use in cheap jewellry, especially in the East Indies. Apparently the word derives from the Malay word 'Tombaga'. The particular alloy used by Canada was 88% copper with 12% zinc.
First isolated in 1783 by D'Elhuyars.
Tungsten is a very hard and brittle metal at room temperature, and is consequently unsuitable for coinage. It is very dense (although not the densest material known), and has the highest known melting point of any metal. Despite these well-known properties, I am told that the US mint tried to make some patterns using tungsten. The dies did not make much of an impression.
Fred Zinkann has made a pattern coin out of an alloy containing 5% Ni, 3% Fe with smaller quantities of copper and cobalt. The dies reputedly broke after three coins had been made.
First isolated in 1831 by Sefstrom.
An element very similar to titanium. A token has been struck by Wah Chang Albany to demonstrate their ability to work in this metal, but no circulating coins have been been struck in this poisonous metal.
Virenium is a German Silver type of alloy containing nickel as well as copper and zinc with a magnetic element as a built in security device. It was first used by the Isle of Man. It has the composition 81% Cu, 10% Zn and 9% Ni. (I am indebted to Jørgen Sømod and Louis Carlson for the latter information).
A name given to a range of alloys usually containing antimony alloyed with tin, copper or lead to produce a white silvery metal used in the manufacture of medallions.
First isolated in 1746 by Marggraf.
A lightweight metal which is cheap and can readily be made into coins. It does oxidise steadily and inexorably, and so is not a very satisfactory coinage metal in its pure form. Generally superseded by aluminium, zinc was used by the Germans for occupation coinage during the two world wars. The metal is an important constituent of brass.
For some years now US and Canadian cents have been made using copper-clad zinc rather than bronze.
First isolated in 1789 by Klaproth.
Similar to Titanium, and used for flash-bulbs and nuclear fuel-rod casings. No true coins have been struck in this metal, but a token has been struck by Wah Chang Albany to demonstrate their ability to work in this metal, and there are reports of an "Islas Malvinas coin" in zirconium, but that is clearly not one produced by the Falkland Islands themselves!
A small number of 'coins' were struck using coal during Germany's hyperinflation period in 1922 as Notgeld.
The Japanese circulated a baked clay 1 sen coin just before the end of the Second World War.
A variety of fibres were used to make coins in a province of China, and I have reports of an asbestos/rubber token for a tramway during the Notgeld period in Germany.
Small glass tesserae of the 1st to 4th centuries AD have been found in Egypt, and were probably used as coins. It is also believed that glass weights found in Arabia were used as currency, as well as some Notgeld items.
Embossed pieces of leather have been used during a number of sieges around the 16th century, and examples of leather tokens are known from Germany after the First World War.
Well, not coins but certainly bank-notes, and Russia allowed postage stamps to act as 'coins' at one time. I have been told that cardboard was used the Netherlands in 1574, in Mexico in 1915, and also in Germany during the notgeld issues after the First World War. That for Grünhain was struck, not printed.
Frequently used for tokens. The Sixth-Form Club at Charterhouse (where I used to teach) uses plastic coin-like tokens for change, and some transport tokens were made in this material. Further examples are Australian Keeling-Cocos tokens of 1913 and 1968.
Australia issues plastic banknotes.
Porcelain tokens are believed to have been used in Ptolemaic Egypt. Porcelain coins were used in Thailand in the early 18th century, and made as Notgeld in Germany.
It has been reported that stamped blocks of salt were at one time used as currency in Gaindhu Province in China at the time of Marco Polo's explorations.
First isolated in 1818 by Berzelius.
Selenium is not really a metal, being more akin to sulphur than the other similar element tellurium. Like sulphur, it exists in a number of allotropic forms, the main ones being red and grey selenium. The grey form is a good conductor of electricity when illuminated, thus its use in light sensitive devices.
A medal has been made of this element to commemorate Berzelius.
Silicon comes in two forms: amorphous silicon which is a brown powder, and crystalline silicon which has a grey metallic appearance.
It is a semi-conducting material, not a metal, and is primarily used in the semiconductor industry.
It is not used for coins in its pure form, but trials have been made with a nickel-silicon alloy (see the section on nickel).
No coins in their characteristic shape have been 'struck' in stone, although very large stones were used as currency on the island of Yap. These items and other non-metallic items used as a medium of exchange in primitive cultures are beyond the scope of this article. If you are interested obtain a copy of 'A Survey of Primitive Money' by A Hingston Quiggin, published by Methuen in 1949 (also reprinted with corrections in 1963).
I have had a report that sulphur was used for Notgeld in Germany. It is a yellow non-metallic solid that comes in a variety of allotropic forms.
Some notgeld and fantasy items have been made out of wood. The famous ones are the 'Wooden nickels' readily available in the USA.
The majority of these metals are either too reactive, too expensive or just too difficult to work to be used in coins and medals, although many are useful as alloying additions in industrial metallurgical applications.
These elements are known as the alkali metals. They are all silvery-white in colour, react vigorously with water, very soft, and react rapidly with air, and are thus totally unsuitable for coins.
Softer than lead but harder than sodium or potassium, lithium is the lightest of all solid elements.
Potassium catches fire when in contact with water.
Rubidium ignites spontaneously when exposed to air.
The first group are known as the alkaline earth metals.
An expensive metal that if burnt creates very toxic compounds. Need I say more!
A reactive and brittle metal, it is stable in dry air but reacts vigorously with water. Having such a coin in your hot sticky hand would have unpleasant consequences!
A ductile white metal, softer and more reactive with water than calcium.
Barium is soft silvery white metal, reacting readily with water.
Strontium and barium are chemically similar to calcium.
First isolated in 1817 by Stromeyer, it seems a medal was made out of this in 1828 in Silesia. The metal burns readily in air.
A liquid at room temperature! Hardly suitable for coins, but would form solid alloys or amalgams (such as used in tooth fillings), and it is possible that amalgams were used for forgeries of silver coins (see the Sherlock Holmes story 'The Adventure of the Engineer's Thumb'). Given the toxic nature of liquid mercury and particularly its vapour, this may have been a foolhardy approach.
A black opaque element harder than carborundum. Well known as a neutron absorber used in alloy form for nuclear reactor control rods.
A soft silvery-white metal which reacts readily with many acids. Apparently it is used in alloys for metallic baseball bats.
Used in ceramic compounds to make high-temperature superconductors.
Very soft silvery white metal. Oxidises rapidly in air. 5 $/g
As mentioned above, this melts all too easily. It is also very expensive.
The semi-conductor that was used for the first transistors.
A highly poisonous element. Three allotropes exist, but the stable form at room temperature is grey and metallic in appearance. It is very brittle. It has been used as an alloying addition in ancient times to make copper more silvery in colour.
Bismuth is a grey-white metal with a pink tinge. It is very brittle.
All elements with a higher Atomic Number than bismuth are radioactive.
All metals in this group have been used for coins or medals.
There are no stable isotopes of this element which is not found in nature. It is a radioactive element, and it seems that there is a quantity in the Irish Sea at present. It is said to be the world's most expensive metal.
A hard white metal, used as an alloying addition for the hardening of platinum and the improved corrosion resistance of titanium, and as a catalyst. 30 $/g
A hard silvery white metal, used as for ruthenium, but also to plate silver, preventing tarnishing. 32 $/g
An extremely hard bluish-white brittle metal which is very difficult to fabricate. 100 $/g
An extremely hard yellowish-white brittle metal which is very difficult to fabricate. 16 $/g
These are all scarce platinum group metals. In addition they are far more difficult to work than either platinum or palladium, the more common elements of the group, making production of coins or medals in these metals extremely difficult, if not impossible. Rhodium and iridium can be cold worked to a limited extent after hot-working, whereas ruthenium presents greater difficulties and osmium is virtually unworkable. Osmium and iridium are used in alloy form for hard-wearing fountain pen nibs.
One or two trial pieces have been struck in rhodium, but is much more often used as a tarnish resistant coating for silver. A fantasy piece struck by the firm John Pinches in iridium is known.
A whole collection of very similar metals known as the Rare Earths. A mixture of these called Misch Metal is used for lighter flints. I am grateful to the web site http://periodic.lanl.gov/58.shtml for information on the lanthanides (substitute the atomic number for the 58 as required).
For lanthanum see above.
This is the most common of the rare earths. An iron-grey metal which oxidises readily at room temperature. 0.125 $/g
The others are:
Praseodymium (Pr), At.No. 59, density 6.77 kg/litre, M.Pt 931°C
Soft silvery metal which goes green in air. 2.5 $/g
Neodymium (Nd), At.No. 60, density 7 kg/litre, M.Pt 1021°C
Used in magnetic alloys. Rapidly tarnishes in air. 1 $/g
Promethium (Pm), At.No. 61, M.Pt 1042°C
Radioactive, with no stable isotope. Longest halflife - 7.7 years.
Samarium (Sm), At.No. 62, density 7.49 kg/litre, M.Pt 1074°C
Used in magnetic alloys. 5 $/g
Europium (Eu), At.No. 63, density 5.25 kg/litre, M.Pt 822°C
A very reactive silvery-white metal about as hard as lead. 7.5 $/g
I believe that europium oxide is the material used in TV's for the red phosphor on the screen.
Gadolinium (Gd), At.No. 64, density 7.86 kg/litre, M.Pt 1313°C
Ferromagnetic silvery white metal. Tarnishes in moist air forming a loose oxide film. 0.48 $/g
Terbium (Tb), At.No. 65, density 8.25 kg/litre, M.Pt 1356°C
Soft silver-grey metal. Fairly stable in air. 30 $/g
Dysprosium (Dy), At.No. 66, density 8.55 kg/litre, M.Pt 1413°C
Very soft (can be cut with a knife). 0.2 $/g
Holmium (Ho), At.No. 67, density 8.79 kg/litre, M.Pt 1474°C
Soft and malleable. Rapidly oxidises in moist air. 10 $/g
Erbium (Er), At.No. 68, density 9.15 kg/litre, M.Pt 1529°C
Soft and malleable. Fairly stable in air. 0.65 $/g
Thulium (Tm), At.No. 69, density 9.31 kg/litre, M.Pt 1545°C
Scarcest of the lanthanides. Bright and silvery metal. Reacts slowly with water. 11 $/g
Ytterbium (Yb), At.No. 70, density 6.96 kg/litre, M.Pt 824°C
Soft, malleable and quite ductile. Reacts slowly with water. 3 $/g
Lutetium (Lu), At.No. 71, density 9.85 kg/litre, M.Pt 1652°C
Soft, malleable and quite ductile. Reacts slowly with water. 6 $/g
There is an American firm that produces tokens (they erroneously call them 'coins', about the size of a US cent) out of many pure metallic elements, including several rare-earths.
Some of the above prices are becoming out-of-date as new techniques in their extraction are developed. Stanford Materials on http://www.stanfordmaterials.com/product.html give recent prices for many of these elements.
Actinium is a beta emitter, but with its decay products it is used as a very strong alpha emitter.
Uranium and thorium are both weakly radioactive, with such long half-lives that they are found in reasonable quantities in nature. The remaining actinides are all radio-active. The activity of uranium is so low that it could be handled with minor precautions, but it would be unwise to make coins out of it! A medal was made out of uranium in Germany in 1956.
I am sure that I have omitted some metals and alloys that have been used to make coins. I would welcome any feedback to produce a more exhaustive list.
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Copyright Tony Clayton 1998-2015
v54 5th June 2015