Actually, not being of that trade, are quarries and mines at all the same sort of thing? Are there mines at quarries? It's all to do with removing valuables from the earth, right? Has anyone survived long enough to wander through the deathclaw quarry?
To be honest, if there's a safe full of precious treasures there, not even if it's a Boone upgrade to make him into a witty talkative charming man and also a range of whips and strapons and a selection of fully modded assault carbines, I still aint going to deatclaw quarry for it. It can [censored] stay there.
Quarries are usually above-ground, and generally they are pursuing whatever makes up the earth at that point. It's something like a marble quarry: just cutting out chunks of a material from a huge amount.
Mines are usually looking for a resource within the earth, rather than the earth itself. We don't mine limestone, we don't have gold quarries.
Most of the mines in Fallout are underground. Maybe strip mining never caught on in the Fallout universe, or maybe they're just so boring the developers never put them in.
Besides, I think the loading screen message everyone is talking about here is just an example, showing how treacherous prospecting can be and how picked over most of the wasteland is. It could also be a metaphor as to how prospectors "mine" the wasteland for treasures of the old world.
My 2 cents.