I'm wondering what people have against the use of "unobtanium", opinion seems to be split between hating it and finding it funny. The way I saw it, it was a nod to people that know the term from the various sci-fi usage and the usage in fiction discussion, as an element with whatever properties you need it to have for the example. It explained everything you needed to know about it, it's incredibly valuable, they don't mention any material properties, so they won't come up in the movie, and for all we know, it isn't even really called unobtanium, it could just be what the '80s vintage coked-up executive IN SPACE called it.