“Given the metallic composition used for the 2009 uncirculated one-cent coins, the same used for the original 1909 Lincoln Cents, the alloy readily tarnishes. The United States Mint has used anti-tarnish treatments to minimize this impact on the appearance of the uncirculated coins. However the alloy used for the one-cent coins in this years’ uncirculated coin set is expected to tarnish more over time than the previous years’ plated zinc one-cent coins”.

2009 Satin Finish Lincoln Cent is composed of 95% copper alloy, 3% zinc and 2% tin. This metal composition was last used on Lincoln cents from 1909 - 1942