The American Silver Eagle is the official silver bullion coin of the United States. It was first released by the United States Mint on November 24, 1986. It is struck only in the 1 troy oz denomination 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 the United States Congress and its weight and content is certified by the United States Mint. The American Silver Eagle bullion coin may be used to fund Individual Retirement Account investments. The United States Mint also produces a proof version for coin collectors. The Silver Eagle has been produced at three mints. One is the Philadelphia mint, and some of those issued there carry a "P" mintmark. In the early years of the series, the San Francisco mint issued proofs and these bear an "S". More recent proofs are from the mint at West Point, New York. The latter have a "W" on the reverse, as illustrated here.