Element Z
From superman.nu: Supermanica
Element Z
Element Z is a mysterious chemical substance which was "believed existed elsewhere in the Universe." It emanates a twinkling multi-colored brilliance in the dark, and feels warms to the touch.
Lex Luthor finds a piece of it on the prison yard and discovers a serum that cures cancer instantly. Superman retrieves a meteor swarm containing Element Z and delivers it to the United Nations. (S No. 149, Nov 1961: "Lex Luthor, Hero! Part 1")