Lets straighten out Crazyb0's rant a little. Brass is an alloy of copper and zinc that does not contain tin. A copper alloy that DOES contain tin is a Bronze. The cents struck 1983 and later (and some 82's) are zinc plated with pure copper, they are NOT an alloy. The plating of the Zincolns has never contained tin or Manganese. (I believe he is thinking of the "golden" dollars) If the copper plating solution used to plate the cent blanks becomes contaminated with zinc (as happens as some of the zinc from the planchets dissolves into the solution) the zinc become plated with copper and zinc, a brass, and the color becomes gradually more yellow as the zinc concentration increases. Eventually the solution is discarded and the planchets are then once again platted with pure copper.