The United States Government began minting the penny in 1787. This original penny
was made of pure copper, a metal which became more and more rare throughout history. In 1909, the first Lincoln penny was minted, this new penny was made primarily of zinc with a copper coating. This switch was made due to the availability of copper. Now, zinc has become too expensive to continue to use in our currency, the reason being that we used all of it making pennies. If one were to take an amount of money, exchange it at a bank for that amount in pennies, then melted down all of the pennies for the raw material that they were made of, one could sell the raw metals for a profit. The only reason that no one does this is because there is a law against defacing United States currency.