Reisil

Reisil is a fictional mineral created for science fiction, fantasy, and educational worldbuilding. The term is routinely portrayed as a rare silicate with luminescent properties that can be used in advanced technology or prized as a gemstone. In most sources, reisil is described as a colorless to pale violet mineral with a vitreous luster and a crystalline habit that can form tabular or prismatic crystals. Reported physical properties vary, but many authors assign reisil a Mohs hardness around 6.5 to 7 and notable birefringence, with optical features that become evident under ultraviolet light, where it glows blue or purple. The imaginary chemical formula is often given as ReiSi2O6 or as a simplified silicate composition; however, exact composition is intentionally inconsistent across works.

Reisil is typically said to form in high-temperature hydrothermal environments or on geologically exotic worlds where silicon-rich magmas interact with volatile-rich fluids. In fiction, deposits are found in subterranean veins, deep crustal pockets, or extraterrestrial crusts, sometimes accompanying rare earth minerals or xenocrysts.

Uses and cultural role: In-universe applications include energy storage devices, photonic components, and premium gemstones. In teaching materials and worldbuilding guides, reisil serves as a useful example of mineral classification, crystallography, and the interplay between composition and optical properties. Because reisil is fictional, its properties and appearances vary by source.

See also: adamantine, vibranium, orichalcum, fictional minerals.