They’re talking about vanadium dioxide’s transition, but it’s still a poorly worded phrase

Form wiki:

The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer (passivation) somewhat stabilizes the free metal against further oxidation.

That's literally 2nd phrase there, right at beginning. Tell me, does that strike you as something to be discovered only in 2017? Or the guys who made the discover(y)/(ies) already seen VO2?

Also wiki is wrong since Vanadium is as rare as Copper. Does Copper strikes you as something rare?

‘Elemental metal’ means the element not bonded to other elements (ie mostly pure vanadium). There’s no reason an element can’t be common but the pure element be rare.

Also the oxide the wiki article is talking about is V2O5, not VO2 (though VO2 was known beforehand - it’s easy to find articles about it from the 50s).

Maybe he meant that "elemental metal" is redundant?

In other words: can we call "metal" anything not in the periodic table?

Alloys of various elemental metals are also metals, but aren't elemental.

This is the wikipedia: https://en.wikipedia.org/wiki/Vanadium(IV)_oxide

Ford was using Vanadium steel in the chassis of his model T in the early 1900s