[adamsmith143]

>The only heavy element that we actually "use up" to any significant degree is uranium

Helium would like a word with you.

[philipkglass]

The only heavy element. Helium is the second lightest of all elements. I didn't think that the post I responded to meant helium because it said heavy elements (plural) and it referred to the far future, after mastering fusion as an energy source.