From 1932 to 1964, the Washington Quarters was struck in a composition of 90% silver and 10% copper. These quarters have a standard weight of 6.25 grams and diameter of 24.3 mm with a reeded edge. During this time period, the mint mark for quarters struck at the Denver and San Francisco Mint facilities appears on the reverse of the coin beneath the olive branches.

In 1965, a new composition was introduced which consisted of an inner core of pure copper with an outer layer of 75% copper and 25% nickel. The overall composition was 91.67% copper and 8.33% nickel. These pieces weigh 5.67 grams and have the same 24.3 mm diameter. These specifications remained in use for circulation strikes through the end of the series. During this period, the mint mark appears on the obverse, to the right of the ribbon in Washington’s hair. Starting in 1980, the Philadelphia Mint began to include the “P” mint mark.
Certain modern numismatic issues have carried different specifications. In 1976, silver clad coins were issued in three-coin proof or uncirculated Bicentennial Sets. These coins had an inner core of 20.9% silver and 79.1% copper, with an outer layer of 80% silver and 20% copper, yielding a net composition of 40% silver and 60% copper. From 1992 to 1998, silver proof coins were issued within the annual Silver Proof Set. These coins were struck to the standards of the original 90% silver coins of the series.
Silver Washington Quarters
Dates: 1932-1964
Composition: 90% silver, 10% copper
Weight: 6.25 grams
Diameter: 24.3 mm
Clad Washington Quarters
Dates: 1965-1998
Composition: 91.67% copper, 8.33% nickel
Weight: 5.67 grams
Diameter: 24.3 mm
Silver Clad Washington Quarters
Dates: 1976
Composition: 40% silver, 60% copper
Weight: 5.75 grams
Diameter: 24.3 mm
Modern Silver Proof Washington Quarters
Dates: 1992-1998
Composition: 90% silver, 10% copper
Weight: 6.25 grams
Diameter: 24.3 mm