Exinite
Exinite is a hypothetical element that appears in science fiction literature, notably in Arthur C. Clarke's novel "Islands in the Sky." It is depicted as a rare and highly valuable mineral, often described as having properties that make it useful for advanced technology. In the context of the story, exinite is mined from asteroids and is a key component in the construction of spacecraft and other sophisticated devices. Its fictional nature means that its properties and uses are defined entirely by the author's imagination, with no basis in actual scientific understanding of elements.
The concept of exinite serves a narrative purpose, providing a plot device that drives the characters' motivations