Nothing. You'd receive an extremely low dose of a type of radiation that's easily blocked by skin, that's all.

If you ingest or inhale it, you're buggered. But if you touch it? Nothing would happen. You wouldn't become a mutant, you wouldn't glow in the dark, you wouldn't gain superpowers. You'd touch a lump of dull grey metal. That's all.

Not very exciting, I'm afraid.