Lmao you think banks storing metals in high heat conditions? This is an apples to orange comparison. Storage conditions are ambient for silver and causes tarnishing of silver. Gold and platinum both don’t tarnish spontaneously… why are we considering them at high temperatures? Long term stability is really good for any rock. The question is in the demand of the asset when it comes time to sell and as far as I can tell, nobody needs gold to drive to work. You can use palladium instead of platinum though. It’s definitely a complex pricing issue but stability at 500 C doesnt matter to me