
Based on the provided information, United States quarters minted for general circulation in 1964 or earlier are composed of 90% silver and 10% copper. These silver quarters encompass several different designs, including the Barber Quarter (minted from 1892 to 1916), the Standing Liberty Quarter (1916 to 1930), and the Washington Quarter (1932 to 1964).
Due to the rising price of silver, the U.S. Mint removed the precious metal from its circulating coinage after 1964. Consequently, quarters minted from 1965 to the present for everyday use are made of a copper-nickel clad composition and do not contain silver.
However, an exception exists for modern collectible coins. Since 1992, the U.S. Mint has produced special silver proof quarters specifically for collectors. These non-circulating coins are also made with 90% silver, but they are not intended for general transactions.


