Feltrange

Feltrange is a fictional mineral described in speculative geology and science fiction literature. It is presented as a layered silicate mineral with distinctive optical properties, notably a blue to violet luminescence under ultraviolet light. In real-world geology, feltrange is not a recognized mineral and does not occur in any documented natural setting.

The term was introduced in the context of world-building for a hypothetical planetary geology scenario and is associated with the imagined planet Vespera. The name is a portmanteau reflecting a textured appearance and a broad color range described in in-universe field guides. Within those materials, feltrange is often depicted as forming through high-pressure metasomatic processes in ultramafic crustal rocks.

Typical properties attributed to feltrange in fiction include a Mohs hardness around 7, a density near 3.2 g/cm3, and a monoclinic crystal system. It is described as transparent to translucent with a vitreous luster and a conchoidal fracture. In many stories, feltrange crystals occur in veined pockets alongside magnetite, olivine, and amphibole, and display a characteristic pale-streak when powdered.

Uses attributed to feltrange in the narratives range from decorative gemstones to experimental energy-storage components and optical elements, leveraging its luminescent response. However, because feltrange is fictional, practical applications and properties are part of world-building rather than empirical science.

See also: fictional minerals, world-building resources.