Heleide

Heleide is a fictional material that appears in speculative fiction, science fantasy, and some tabletop role-playing game settings. Described variously as a crystalline or glassy substance, it is known for unusual interactions with light and energy.

Etymology and origins: The term heleide is a coinage used by writers; there is no single canonical origin. In different works it may be explained as derived from invented languages or as a portmanteau of 'heli-' and '-ide' to evoke light and mineral chemistry.

Properties: In most depictions, heleide is lightweight yet strong, with a high refractive index and exceptional thermal stability. It can store, guide, or release energy, and may exhibit luminescence or non-linear optical effects. Variants include heleide glass, heleide crystals, and alloyed forms with metals or ceramics.

Applications: In-universe applications range from energy storage cells and power conduits to armor, sensors, and optical components. In some stories, heleide is mined in isolated regions or synthesized in advanced facilities; its scarcity drives trade and conflict.

In fiction: Heleide is used as a plot device to enable advanced technologies or as a symbol of pristine alien science. Real-world science does not recognize heleide as a real material; it remains a fictional concept.