The coin described is a 1966 Jefferson Nickel, a U.S. five-cent piece produced during a time when millions of these coins were minted. This particular nickel is notable for its lack of a mint mark, suggesting that its place of production is unknown, but it likely originated from one of the U.S. Mint facilities that did not mark its coins with a mint letter during that period. The Jefferson Nickel is characterized by its diameter of approximately 21.2 millimeters and a weight of 5 grams, consistent with its specifications as a nickel made primarily of copper-nickel alloy. It features Thomas Jefferson’s profile on the obverse and Monticello, his Virginia home, on the reverse. With a total mintage of around 156 million coins, this 1966 Jefferson Nickel is common among collectors and typically carries a modest value in circulated condition. However, its precise valuation can fluctuate based on its grade, which could range from good to uncirculated. Because the coin's dimensions and properties are well-defined, it is suited for both numismatic study and everyday transactions. In summary, this is a classic piece of American currency from the mid-20th century, representing both the historical value of the Jefferson series and the practical functionality of the nickel denomination in everyday commerce.