Re: Helium aquisition and storage. Area Science History

Finding the right reference book is half the battle for a question like this.

According to Greenwood & Earnshaw's "Chemistry of the Elements," 1st Ed, 
p. 1044, terrestrial helium is the product of radioative decay (helium-4 from 
uranium, thorium and their daughters; helium-3 from the decay of hydrogen-3).

Helium is found in tiny trace quantities throughout the Earth's crust, but tends
to accumulate in natural gas wells. To extract helium economically, the helium 
concentration in the natural gas needs to be above 0.4%. This concentration is 
found in several US wells, and in some in Eastern Europe (mainly Poland).

This information is almost 20 years old, but should still be OK. It's possible 
that some of the gas wells discovered in the past 20 years around the world also 
have economical quantities of helium, but my reference doesn't show it.

                                            Dan Berger