I've come to a realization on my world building, but first: some context. In my world there are no beings above the laws of magic. Gods are simply beings naturally skilled in manipulating entropy. In particular, dragons are predominantly worshipped as gods in the region I mostly work on. My spin on mithril is a metal treated and forged with the help of the gods themselves. Superheated with dragonfire, imbued with magic by dragon lightning (D&D style dragon breath). Turns out, there's already a metal that melts at super high temperatures, needs super high voltages to treat, is super light doesn't oxidize in room temp... I could go on and on. Aluminium. Aluminium is a near perfect fit for mithril in my world. Sure I can just put on a few magic properties whenever I need, but aluminium as the base metal pre-magic-imbue is much better than steel for my use.