Helium

Helium was spotted as an unexplained yellow line at 587.6 nm in the spectrum of the solar corona during the 1868 eclipse, and named after Helios twenty-seven years before William Ramsay finally found it on Earth in 1895, seeping out of the uranium mineral cleveite. That is its terrestrial origin in general: nearly all of it is alpha particles from the decay of uranium and thorium, trapped in the same geological traps that hold natural gas, and it is extracted commercially from gas fields in Texas, Qatar and Algeria. With the weakest interatomic forces of any element it stays liquid down to absolute zero at atmospheric pressure and becomes a superfluid below 2.17 K, climbing the walls of its container. Party balloons are a trivial use of a genuinely finite resource whose real work is cooling MRI magnets.