cilën

Cilën is a fictional mineral featured in science fiction and fantasy settings. In many worldbuilding contexts, cilën is valued for its natural glow, stability under radiation, and potential use in lightweight, high-performance technologies.

Etymology and naming conventions vary by author, but the name cilën is commonly drawn from constructed languages and is often linked to meanings related to light, glow, or crystal. The term is used consistently within a given work to refer to the same substance and may have cultural associations unique to that setting.

Physical properties attributed to cilën also differ across portrayals, but it is typically described as forming prismatic crystals that range from pale blue to green. It often exhibits faint photo-luminescence, emitting light after exposure to ultraviolet or other energy. In many depictions, cilën has a hardness around 6.5 on the Mohs scale, a density near 3.3 g/cm³, and a refractive index around 1.58, with strong dispersion and imperfect cleavage along two directions.

Occurrence and formation are explained through various fictional geologies. Cilën is said to occur in hydrothermal veins within crystalline host rocks such as basalt or granitic formations. Extraction usually requires careful handling to preserve its luminescent core, and processing may involve thermal or chemical treatment to stabilize its glow for use in devices or jewelry.

Applications and role in culture vary by work. Common uses include jewelry and decorative installations, light sources for distant lanterns, and, in some plots, energy storage or sensing components. Cilën often holds economic and symbolic importance in mountain or mining cultures, sometimes functioning as a trade good or ceremonial material.

See also: list of fictional minerals, glowstone, gemstone-based technologies.