Please do post an obverse pic. As Druu said, it is possibly a silver proof from a mint set not intended for circulation. The "S" mintmark will help clarify and also the weight if you can get that. You say it's light but a silver proof weighs more than a normal clad proof/business strike.
The clad proof/business strike should be 5.67g. The silver proof should be 6.3g.

The clad proof/business strike should be 5.67g. The silver proof should be 6.3g.
In Memory of Crazyb0 12-26-1951 to 7-27-2020
In Memory of Tootallious 3-31-1964 to 4-15-2020
In Memory of T-BOP 10-12-1949 to 1-19-2024
In Memory of Tootallious 3-31-1964 to 4-15-2020
In Memory of T-BOP 10-12-1949 to 1-19-2024






















