sileille

Sileille is a fictional gemstone featured in fantasy and speculative fiction settings. Described as a rare silicate mineral, it is prized for its iridescent play of color and a subtle, inner glow that many depictions attribute to trace elements within its crystal lattice. In most stories, sileille is associated with high craftsmanship, ceremonial use, and sometimes magical or technological applications.

Etymology and origins of the term sileille are fictional; the word is a neologism created for narrative purposes and does not have a widely recognized real-world etymology. It is typically treated as a proper noun referring to a single mineral species within its fictional universe.

Physical properties in fictional treatments often include transparency to translucence, with a pearly to glassy luster. Reported hardness is commonly placed in the mid-to-high range on the Mohs scale (about 6–7), making it durable enough for jewelry yet workable for artisan cuts. Colors range from deep blues and violets to greens, and some portrayals show chatoyancy, color-shifting effects under different lighting, or faint fluorescence under ultraviolet light.

Occurrence and mining are described as localized to specific geological zones in the fictional world, such as hydrothermally altered veins or metamorphic rock pockets. Crystals are depicted as brittle, requiring careful extraction and precise cutting. Processing yields polished stones used in jewelry, regalia, or as components in imagined energy storage or enchantment systems.

Sileille’s cultural role varies by work but commonly centers on prestige, symbolic power, and the material basis for both trade networks and conflicts within its fictional ecosystem.

See also: Fictional minerals, List of gemstones in fiction.