It would be cool if we took inspiration from alchemy for some of the higher-concept magics that come from metal. For instance, gold having healing properties, silver stimulating metamorphosis or mental power, or mercury affecting velocity. Things like that.

Platinum could be basically the infinity-plus-one to the infinity-minus-one that is titanium. Platinum would be the metal of divinity, of perfection crafted from base metal. Mostly taking inspiration from Platinum Angel/Emperion here, but I feel like it's fitting.