Talc as Rust Protection

[J. Clarke]

So why only in gas wells? There are plenty of places on Earth where there is "a lot of cover" and no helium.

[Andy Dingley]

But where else do we go drilling for it, into a large volume where the lighter gases have already had a chance to stratify.

[George]

Precisely. The geology of helium wells is fairly unique, but the real reason for examining it is the methane.

Then there's the question of radioactive source, which we're unconcerned about, but is required for the phenomenon.