Your coin is a business strike coin, not a proof struck coin. The difference is quite noticeable even to the camera.

The proof coins after 1968 had the "S" mint mark on them. (There were business strike cents with the "S" during 1968-1974 that were not proof coins.) Your coin is a business strike coin with perhaps a drop of water/oil or something blocking the field where you thought it an "S". But your coin never had an mint mark in the location. It is a 1975 plain cent business strike cent with a stuck error. Very minor error.

The proof coins after 1968 had the "S" mint mark on them. (There were business strike cents with the "S" during 1968-1974 that were not proof coins.) Your coin is a business strike coin with perhaps a drop of water/oil or something blocking the field where you thought it an "S". But your coin never had an mint mark in the location. It is a 1975 plain cent business strike cent with a stuck error. Very minor error.























