The United States Mint stopped using silver to produce quarters at the end of 1964. Any U.S. quarters produced by the Mint for general circulation dated 1965 or later are copper-nickel clad coins. Quarters dated 1964 and earlier contain 90 percent silver.
In the early 1960s, the supply of silver for U.S. coinage was running low. As Congress and the Kennedy Administration debated the role of silver in manufacturing coins, the price of silver jumped 10 percent and continued to rise an additional 30 percent by 1962. Congress passed legislation to remove all silver from United States coinage by the end of 1964.
Depending on the current price of silver on the commodities market, the 90 percent silver coins minted prior to 1965 may be worth more than their face value. For example, if silver is selling for $20 per ounce, 90 percent silver quarters are worth about fourteen times their face value.
When still producing silver coins, the United States government insured that each coin had an amount of silver proportionate to its denomination. This meant a quarter dollar had approximately 25 percent of the silver content of a silver dollar, and a dime had approximately 10 percent of the silver dollar's content.