Red-Gold Kryptonite
Red-Gold Kryptonite is formed when Gold and Red Kryptonite fuse together into an alloy.
When exposed to it, Superman gets temporary amnesia but his super-powers are unaffected.
In July 1965, Superman encounters a Red-Gold meteorite that had sunk into the Atlantic Ocean while he was rescuing two atlantic cable repair divers that had gotten tangled with a whale. He got struck by the whale near the meteorite and lost consciousness. When he comes to, he has no memory of his identity and everybody thinks he is dead because a diver sighted the golden portion of the meteorite and thought he had lost his powers. Later, while walking back to the Daily Planet, a truck hits him onto high tension cables and he gets his memory back. (S 178, Jul 1965: "When Superman Lost His Memory!")