NGC 1977-D Eisenhower dollar transitional off-metal, struck on a 40% silver planchet. The 40% silver planchet was intended for a San Francisco Mint silver Ike dollar, but some were accidentally shipped to Denver and struck. Because the planchet is from the prior year, it is a transitional off-metal.
Only a very few are known (around a dozen examples), and it is a rarity in the Ike dollar series. This is an affordable example, as it has a scratch obverse behind Ike's head.
Mintstate examples often sell for around $20,0000, making this an affordable example.
AU details obverse scratched (the scratch is behind Ike's head.) Overall a decent coin, and someone doubtless made the scratch in order to test the metal and see if it was silver.