The fictional mineral sought by humans on Pandora in James Cameron’s Avatar is unobtanium. In the film, the resource is valuable enough to motivate a large-scale mining operation on the moon.
The term “unobtanium” is a playful engineering expression for a material with ideal or impossible properties. Avatar turns that informal word into the name of a valuable fictional substance with extraordinary commercial importance.
The mining project brings human military and corporate interests into conflict with the Na’vi, whose homeland and sacred places are threatened by extraction. This resource conflict is one of the film’s central story engines.
Unobtanium is not a real chemical element, mineral species, or established material. It is also distinct from the Marvel substances adamantium and vibranium, and from dilithium in Star Trek; those belong to separate fictional universes.