What is the value of a 1989 quarter that has copper on both sides?

Answer 1

There are two possibilities:

If the coin is thinner than a regular quarter, you have what's called a lamination error that occurred when the outer layers of cupronickel cladding detached from the copper core. Lamination errors among clad quarters retail for $10 to $15.

If the coin is the same thickness and weight as a normal quarter, someone plated it. Unfortunately that makes it an altered coin worth only face value.

Answer 2

That's called a lamination error. Dimes, quarters, and halves are made of what's called a "sandwich" metal consisting of two outer layers of cupronickel (the "bread") bonded to a pure copper core (the "meat"). Sometimes the bond doesn't hold and one of the outer layers comes off. That can happen before or after the coin is struck. Because of the huge number of coins minted and hectares of metal stock that's used, lamination errors are more common than you might think. However your quarter still could have a retail value of around $10 so it's still a nice find.