Selailun

Selailun is a fictional mineral described in speculative fiction and worldbuilding narratives. In common in-universe depictions, selailun is a layered, luminescent mineral that responds to infrared light with a visible glow and shows potential for energy storage and advanced optics. The term does not refer to a real substance outside its fictional context, and its characteristics vary across different works.

Etymology of the name combines elements from in-world languages, typically intended to evoke images of a moon-borne stone or a mineral associated with the sea, depending on the author. The name is usually treated as a proper noun with no universal etymology across different stories.

In-universe properties and formation describe selailun as a silicate-rich mineral doped with rare earth elements. Reported physical characteristics often place it in the mid-to-high hardness range and give it a moderate density, with a distinctive bioluminescent glow that intensifies under certain lighting. Its formation is commonly linked to hydrothermal activity or subduction-zone geology, where mineral-rich fluids crystallize within crystalline veins and caverns.

Occurrence and discovery in fiction place selailun in remote planetary settings or mythic geographies. It is frequently mined from deep veins in volcanic or tectonically active regions, sometimes requiring specialized mining and safety protocols due to its glow and potential fragility.

Applications in fictional contexts include energy storage, luminescent signage, and components for optical or quantum devices. The glow of selailun is sometimes portrayed as stable over long periods, making it attractive for navigation aids and medical imaging within narrative universes. Its portrayal can reflect broader themes about resource scarcity, technological dependence, and environmental stewardship in speculative worlds. See also: fictional minerals, luminescent minerals.