Quarters minted before 1965 in the United States contain 90% silver. A quarter from 1964 weighs 6.25 grams. Therefore, such a coin contains 0.90 * 6.25 grams = 5.625 grams of pure silver.
The silver content of these coins is a significant factor contributing to their value, often exceeding their face value. This difference is driven by the intrinsic value of silver as a precious metal and its fluctuations in the global market. Numismatic value, based on factors like condition and mint marks, can further enhance their worth. Pre-1965 quarters represent a tangible link to a period in U.S. monetary history when circulating coinage contained a substantial amount of silver, a practice discontinued due to rising silver prices.