Hellyel

Hellyel is a fictional mineral term used in speculative geology and worldbuilding. It is not recognized by the International Mineralogical Association and has no confirmed occurrence in Earth’s geology.

Etymology and naming are attributed to the fictional Helly Range, described in various narratives as the site of its first discovery. The name is sometimes explained as a portmanteau of a fictional explorer and the suffix -el.

In these stories, hellyel crystallizes in a hexagonal system with prismatic crystals. The mineral is depicted as pale blue to greenish, transparent to translucent, with Mohs hardness around 6.5 and a density near 3.2 g/cm3. Optical properties are imagined as a refractive index near 1.62–1.66.

Formation and occurrence are described as taking place in metasomatic environments within carbonated rocks under high-grade metamorphism, often together with quartz, tourmaline, beryl, and kyanite.

Uses in the fiction include gemstone applications and potential energy storage through luminescent centers activated by UV light. In reality, hellyel is not a real mineral and has no standing in mineralogical records.