Planchet does not look like copper, but if there was nickel struck on a copper planchet of the same size as a copper nickel planchet it would have, for all practical purposes, the same weight. Copper and nickel have very nearly the same density (8.96 g/cm3 vs 8.90 g/cm3) and therefore the same weight for the same volume. The actual change in weight would be in theory .008 grams an amount equal to 4% of the allowed mint tolerance.