Might seem a little crazy now but in potential TEOTWAWKI long-term environment, copper would come in handy for small transactions. A silver dime might have significant value, too much for some transactions.
In the U.S pennies have been basically zinc for decades, time consuming to search through. But nickels are still made of copper, nickel, and manganese.
They actually switched our nickles earlier in 1983, but pennies were still copper till in mid 90's. I do also tuck away the early nickles, but not to the same extent.