Two things:
1. The working prototype of Lumeloid was tested and proven to work. So it isn't "unobtainium." A major oil company offered him $9 million (IIRC) for the US Patent which he turned down for fear they will sit on the invention and not develop it to aid mankind. Would they do that for unobtainium? (Do a Google search using Lumeloid, Dr Alvin Marks, you'll find it).
2. Of course I know the US isn't on the equator and neither are the majority of Americans at the exact latitude computed in the table I responded to. And your point is???
Ping me if he ever begins shipping product!
--Boot Hill