Details about copper-nickel in coinage are available at www.copperalliance.org.uk/applications/coinage.
Useful Properties for Coinage
The success of copper-nickel in good-quality coinage is due to several useful properties:
- Corrosion resistance: Copper-nickel alloy coins do not tarnish.
- Electrical conductivity: Copper-nickel coins have specific electronic signatures that help prevent fraud in vending and coin-handling machines.
- Antimicrobial properties: Copper-nickel coins are much more sanitary than coins that do not contain copper. This is because copper surfaces kill dangerous bacteria, viruses and fungi quickly and with a high degree of efficacy.
- Durability: Copper-nickel coins can survive at least 30 years in circulation. This is one reason why copper-nickel was chosen for the 1- and 2-euro denominations.
- Malleability: Clear images and distinct edging can be struck on copper-nickel coins.
- Allergy risk: Billions of people handle copper-nickel coins with no allergic reaction at all. The risk of contact dermatitis with copper-nickel is very small.
- Ease of stamping: Large volumes of coins can be struck with minimal maintenance.
- Recyclability: Copper-nickel coins are 100% recyclable. Brand new copper-nickel coins can be minted from recycled metals.
It’s the combination of all of these properties that enables copper-nickel to be a unique and valuable coinage material today.
Usage From Ancient Times to the Present
Greco-Bactrian kings circulated the first copper-nickel coins around 235 B.C.E. Since that time, many civilizations minted durable, corrosion-resistant coins made from copper-nickel.
The 1 euro coin is composed of a silver-colored inner section (75% Cu, 25% Ni clad on nickel core) and a copper-colored outer section (75% Cu, 20% Zn, 5% Ni). The 2 euro has a reversed look and somewhat different composition: a copper-colored inner section (75% Cu, 20% Zn, 5% Ni clad on nickel core) and a silver-colored outer section (75% Cu, 25% Ni).
Copper-nickel was first used in the U.S. for three cent coins back in 1865. Five cent copper-nickel coins were minted the following year. Today, the alloy remains popular in U.S. coinage: the Jefferson nickel is 75% copper and 25% nickel; quarters and dimes minted since 1964 and half dollars minted since 1971 are clad with copper-nickel.
In the U.K., silver-colored coins minted between 1947 and 2012 were made from copper-nickel. In January 2013, the Royal Mint began a programme to recover cupronickel five pence and ten pence coins from circulation. The 20p (16% Ni) and 50p (25% Ni) coins are still made with copper-nickel.