This coin is a 1990 Jefferson Nickel, which was minted at the San Francisco Mint, identifiable by its "S" mint mark. As a proof coin, it was specially struck to provide a highly polished and reflective finish, ideal for collectors. The coin is composed of a Copper-Nickel alloy and has a weight of 5 grams, a diameter of 21.21 mm, and a nominal value of five cents. The 1990 minting of the Jefferson Nickel features the iconic profile of Thomas Jefferson on the obverse, while the reverse showcases Monticello, Jefferson's renowned estate. With a total mintage of 3,299,559 proof coins, this particular piece is a notable entry within the Jefferson Nickel series. This coin is classified under the "Coins" subtype and carries the denomination of 5¢, which is used in everyday transactions as a nickel, commonly referred to as a half dime during earlier periods of American currency. The coin's pristine proof finish and limited mintage make it a valued item for collectors and numismatists alike.