We use coins on a daily basis. We talk about their values, and collectors like us discuss their designs in great detail. However, in the absence of some precious metals in the coin, we rarely investigate what metals make up the coin and why they are used. I thought I could.
Can we use any metal?
In fact, no. We must not forget that coins are a physical and practical manifestation of money. We manage, maintain and exchange them very regularly. So, coins must have some basic features
Must be safe to touch coins.
We can’t get radioactive coins or material that could be toxic to humans.
Coins must be durable.
We would like the coins to last 30 years longer. The metal used must be sufficiently hard and not break down due to constant human processing or weather conditions. Fast-rusting coins are of no use to us. Thus, the metal must have high abrasion resistance and anti-corrosion properties.
Coins should be easy to produce.
We should have tens of millions (or more) of coins in circulation. We need to use efficient processes to produce this figure. We use stamping and pressing, so the metal must be soft enough to use molds to do this.
The value of the metal must be less than the face value of the coin.
If we made coins using gold, they would disappear as much as they were minted, and the country would go bankrupt!
As conditions change over time, it is not always as clear as you might think. Before 1992, British coins were an alloy known as 97% copper, 2.5% Zinc and 0.5% tin, Bronze. Twenty years later, that meant 1.5 pennies of copper per penny.
Therefore, the range of suitable metals is limited and in most cases one or more metal alloys are used.
Coin metals have changed over the years
To avoid the penny problem described above, since 1992, the British penny has been 94% steel and only 6% copper-plated steel.
There was a similar problem in America. Coins were made of copper (except during the war years, when copper was declining), but these days it is zinc-plated.
Silver has been a popular material for coinage since ancient times. In Britain, until 1921, silver coins (such as shillings, fluorine, semi-crowns) were 92.5% pure silver (pure silver, the rest was generally copper). It was 50% silver, and until 1947 there was no real silver in “silver” coins.
Cupronickel (75% copper, 25% nickel) has become a popular choice to replace silver. Cupronickel is as shiny as silver and is very resistant to corrosion in seawater. However, until 2011, the price of copper was enough to drive low-denomination silver coins (5p, 10p) to use nickel-plated steel (94% steel, 6% nickel).
The 5 pound (which replaced the 25p crown in 1990) £ 50 coin is still Cupronickel (75% copper, 25% nickel). For some reason, 20 coins are called Cupronickel, but in different proportions they contain 84% copper and 16% nickel.
Because the coins lasted longer than banknotes, the One-Pound note was replaced by a one-pound circular coin, introduced in 1984. To give a golden color, the alloy was 70% copper, 24.5% zinc and 5.5% nickel.
The two coins have been around for some time, but not in the UK. In 1692 there was a tin with a copper stopper, but for most purposes it was a first of 2 pounds.
Two Pound (2 pound) coins are bimetallic coins introduced in 1998 (although the former dates back to 1997). The outer ring is Nickel-Brass (76% Copper, 20% Zinc, 4% Nickel) and the inner ring is Cupronickel (75% copper, 25% nickel).
Having different materials for the outer and inner circle shows that the outer circle can be harder than the inner circle and will protect the coin. Counterfeit money is a perpetual problem, making it difficult to reproduce.
Unfortunately, coins are easier to make than banknotes. By 2014, it was estimated that 3 percent of round pounds were counterfeit, and Royal Mint rebuilt one pound in the form of a 12-sided two-metal coin with many internal security features.
A new one-pound coin was introduced in 2017. The outer ring is gold-nickel-brass (76% Copper, 20% Zinc and 4% Nickel) and the inner ring is a silver-nickel-plated alloy. Royal Mint hit 300 million of them!
Precious Metal ingots and proven coins
The UK’s gold coins are mainly Gold Sovereign and Gold Britannia and their families.
Years ago, Sovereign was a working coin that was often minted and added to make a very soft metallic copper coin harder and more resistant to abrasion than gold. The sovereign gold is 22 carats; it is traditionally 11/12 gold, 91.67% gold as 1/12 copper.
These days, bullion coins are only lightly processed and the proven versions are almost untouched, so the UK went with this trend and the gold Britannia was minted at 999.9 gold (99.99%).
Silver Britannia is 999 silver. Royal Mint also uses Platinum for some coins at the 0.9995 standard.
Some silver coins are covered with gold. It is called an alloy of gold and silver Electrum.