[alderz]

Metals get rust by an oxidation process.

[SV_BubbleTime]

I’m not Latin expert, but I think iron, or ferus metals are the only ones that “rust”. Raw aluminum starts oxidizing the moment air hits it, anodizing is specially oxidizing aluminum then dying it, and of course this is more true for metals like potassium that dull while you are looking at them, but I’ve never heard anyone say these metals “rust”, they oxidize.

[ithkuil]

The word "rust" has Germanic origins, with the meaning red/reddish.

Latin rubigo (rust) also derives from the word for the color red.

They may have a common ancestor (I don't know)

[SV_BubbleTime]

Good one, I just assumed Latin. You’re probably closer with Germanic.

Still, reddish, we’re likely back to ferrous metals.