When it comes to collecting Jefferson nickels, the 1964-D holds an interesting place in American numismatic history. As the last year before the U.S. Mint transitioned from silver to copper-nickel clad coins for dimes and quarters, 1964 was a significant transitional period for American coinage. 
 
This coin has one the most valuable 1964-D nickel errors called a "repunched mint mark", where the “D” was stamped twice, slightly offset. The picture above display a doubled or “shadow” D mint mark.