Mercury

Iridium Metal: On top of it being the rarest it is also the least corruptible of all metals, the densest, one of the most expensive and extremely hard to boot. With a list of ‘mosts’ like that why don’t we see A-listers flaunting their Ir bling? Well, because there’s one more quality added to that list of mosts: it’s fiendishly difficult to work with.