Illuvie

Illuvie is a fictional mineral used in speculative geology and science fiction. It is described as a translucent, opalescent material with strong iridescence and a variable refractive index. In-universe etymology often links the name to illuvio, a term evoking layered deposition.

Formation and composition: In many depictions, illuvie forms from rapid deposition of silicate-rich vapors in low-gravity, irradiated environments such as nebular dust or regolith on small moons. Its lattice is said to contain metallic inclusions that produce color shifts under different light. Reported hardness is around 6 on the Mohs scale; density is typically given as about 3.0–3.5 g/cm3, though values vary by author.

Occurrence and extraction: Illuvie is placed in basaltic seams, glassy ejecta, or crystalline-rich layers. Extraction requires careful cooling and vibration control to prevent cracking. Some stories describe instability under strong radiation, requiring shielding during mining.

Uses and significance: In fiction, illuvie is valued for luminescence and optical properties and is sometimes proposed for energy storage or actuation. It is depicted as a rare, desirable resource whose availability can influence trade and geopolitics in speculative worlds.