What was the lightest weight coin ever minted by the US Mint?

In 1851, the US Mint issued a silver three-cent coin. It was composed of 75% silver and 25% copper, had a six-pointed star on one side, a Roman numeral III on the other, and — weighing in at four-fifths of a gram — was the lightest coin ever produced by the US Mint. The silver three cent piece was discontinued by the Coinage Act of 1873; at that time, a three cent nickel coin was issued, made up of copper and nickel and slightly larger than the silver version. Since it was the exact size of the dime, the coin never became popular and it was taken out of circulation in 1889. The Coinage Act of 1792 established the US Mint in Philadelphia, on April 2, 1792. The act also specified that the national currency would be based on a decimal system, with the dollar as its main unit, and specified the measurements, weights and composition of the coins, including directives for the emblems that would appear on each side.