[dead]

The US government has been pretty good about cleaning up the UXO it knows about, which means what's left is the UXO it doesn't know about. You'll find it near most of the current and former testing ranges, particularly Yuma Proving Ground where there's trails leading right from the adjacent BLM land into areas with potential UXO. The only real barriers are a few signs and the law.

I see quarries everywhere, and they’re kind of required near any city or road project around Australia. Never considered them as a mine though… more like a ‘general resource site’?

Wouldn't that also filter out every open cut surface mine that strips overburden and directly extracts near surface coal, copper deposits, iron ore, etc.

Not every mine is a "classic" underground mine with tunnels, etc.

See (for example) the W.Australian SuperPit gold mine which consolidated every shaft mine in a particular region into a single open pit that goes deeper than any pre existing underground mine in that area.