Ancient coins were designed and made to be used as currency, not as personal ornaments or collectible items. Today, different materials are used for coins intended for circulation than for those intended for collectors.
This is perhaps the most fascinating fact about modern coins, and the most overlooked as we go about our daily affairs, paying for our morning coffee with the quarters we have set aside in the car’s coin tray, or nonchalantly dropping pennies in the small cup next to the cash register. In essence, while the materials used in minting must ensure durability, their value cannot be higher than the face value of each coin once in circulation. There is science behind this minting madness.
There is another reason why the minting industry must employ materials whose market value is lower than the value of the coins being made: as a deterrent for those who would steal, remelt and resell the materials. Yes, this is why copper thieves dismantle pipes from sinks rather than steal pennies. The copper in the pipes is worth more.
Due to the changing value of copper, American pennies have been made with an alloy of zinc and copper since 1982. Prior to this, they were made of various grades of copper only.
Today, coins that are not used for circulation are frequently made with experimental alloys, but they must always be made to sustain repeated handling and to resist corrosion as well. The typical lifespan for a coin is 30 years. It can get handled hundreds of times in a single day, as well as be subject to varying temperatures and changing humidity levels.
Here is another interesting consideration: The lower a coin’s denomination, the greater the challenge in finding materials that will provide durability and ease of minting while not exceeding the coin’s final market value.
To be continued…