Brandon Sanderson has been my favorite fantasy writer for some time. He's known for making magic systems that follow strict rules, which makes his world's interesting. Wizard's just can't fling fireballs whenever they want.
Anyway, his most famous series is the Mistborn series in which people swallow and burn a specific set of metals use a very specific set of powers. Burning pewter allows you to have enhanced strength. Burning tin allows you to have enhanced perception.
Two powers allow you to affect emotion. Burning Zinc allows you to enhance emotions. Burning Brass soothes emotions. Aluminum blocks these powers so the new book has aluminum-lined helmets. Seriously. I'm not making this up.