It was first released by the United States Mint on November 24, 1986. It is struck only in the one-troy ounce size, which has a nominal face value of one dollar and is guaranteed to contain one troy ounce of 99. 9% pure silver. It is authorized by Title II of Public Law 99-61 (Liberty Coin Act, approved July 9, 1985) and codified as 31 U. S. C. § 5112(e)-(h). Its content, weight, and purity are certified by the United States Mint. In addition to the bullion version, the United States Mint has produced a proof version and an uncirculated version for coin collectors. The Silver Eagle has been produced at three mints: the Philadelphia Mint, the San Francisco Mint, and the West Point Mint. The American Silver Eagle bullion coin may be used to fund Individual Retirement Account investments.