During the modern era, regular proof coin production has taken place at the San Francisco Mint. Accordingly, these coins should carry the “S” mint mark. On four separate instances, proof Roosevelt Dimes have been struck at the San Francisco Mint without the required mint mark (Buy on eBay).
The first situation occurred in 1968. At this time, the Philadelphia Mint was responsible for making the proof dies, which would be shipped to San Francisco to be used in production. At least one die was sent lacking the mint mark. Only a small number of dimes were struck with the die and released before the mistake was discovered. The issue is rare with only 12 to 14 examples known across all grades.
Two years later in 1970, a similar situation occurred and more proof Roosevelt Dimes were struck without a mint mark. This time production from an entire die pair was produced and released before discovery, resulting in an approximate mintage of 2,200 pieces.
The 1975 “No S” Proof Roosevelt Dime is the rarest occurrence for this error type. An extremely small number of proof coins missing the mint mark were released. The coins are so rare that they were not discovered until 1978 when two examples surfaced. These coins are now considered one of the major rarities of the 20th century with an estimated 2 to 5 pieces known.
One final time in 1983, proof dimes were minted without the “S” mint mark and released within the annual proof sets. The approximate mintage for the “No S” proof dimes for this year was 3,000 to 3,500 coins based on estimated die life at the time of mintage.
- Designer: John R. Sinnock
- Composition: 91.67% Coper, 8.33% Nickel
- Weight: 2.27 grams
- Diameter: 17.9 mm
- Edge: Reeded