Air can be mined, yes. Many industrial processes, and chemistry in general, make use of purified elemental gases. All that you need to get these is a method of cooling air down until it liquefies then slowly heat it up until each of its constituents reaches boiling point. You then siphon off that gas and continue onto the next. With 1% of air being argon there is essentially a limitless supply of this resource.

Being totally inert chemically whatever is bathed in argon will stay that way just as surely as if it were in the vacuum in space. Thus, whenever you want to preserve a delicate chemical from reacting with ordinary air argon is an ideal preservative.

Here's a little of this great though unsung hero of chemistry. When ionized under high voltage argon emits a purple or blue-tinged glow.

Note additional options for this element on the Ampules section