järglastes

Järglastes is a term used in speculative fiction to designate a class of iron-rich glassy materials. They are typically described as amorphous solids composed mainly of silica and iron oxides, with dispersed metallic iron inclusions that create a dark, metallic sheen. The structures are non-crystalline, giving them the optical scatter of glass and, in some depictions, magnetic or conductive properties.

Formation and occurrence: In fiction, järglastes form when ferruginous silicate melts are quenched rapidly, locking in a disordered network. They may occur naturally in planetary crustal processes, meteorite impacts, or volcanic vents, or they may be produced synthetically by melting ferruginous glass and cooling it rapidly. The addition of trace elements such as titanium or chromium can alter color and magnetism.

Physical properties: Järglastes typically have a high refractive index and a color spectrum from deep coppery-brown to nearly black. They are hard like glass (Mohs around 5–6) but brittle, and iron inclusions can render them weakly to moderately magnetic. They resist corrosion in some environments but are prone to fracture under thermal shock.

Uses and cultural role: In world-building, järglastes appear in optics, magneto-electronic devices, and armor concepts, as well as in jewelry for their luster and supposed mystic properties. In some stories they serve as ceremonial objects or as a material with energy-storage capabilities.

Etymology: The name combines references to iron and glass in several languages, used by authors to evoke a fused iron-glass material.