Hlustum

Hlustum is a fictional mineral species commonly described in speculative geology and science fiction. In these contexts, hlustum is depicted as a green to blue-green silicate-oxide mineral that forms in hydrothermal environments.

In terms of properties, hlustum is often described as crystallizing in the monoclinic system with prismatic habit. Reported hardness ranges around 5–6 on the Mohs scale, and the mineral is said to have a vitreous luster. Its color spans green to blue-green, with a pale green streak and transparency that can be translucent to transparent under the right conditions. Descriptions vary by author, but the material is typically portrayed as relatively nontoxic and stable under moderate surface conditions.

Chemical composition is presented as variable, usually involving calcium, sodium, magnesium, and iron balanced with silicon, oxygen and hydroxide. Trace rare earth elements may be mentioned in some narratives, though exact formulations are not standardized across sources in fiction.

Occurrence and locality are likewise fictional. The type locality is often placed in the Khaldor Massif within the Aurelia region, with hlustum forming in pegmatitic veins and in zones of contact metamorphism. It is frequently described as co-occurring with quartz, albite and chlorite, and sometimes as exhibiting luminescent properties when exposed to ultraviolet light.

Etymology notes that the name hlustum derives from a fictional root meaning glow in the Hlustran language, paired with a mineral-suffix. It is important to emphasize that hlustum has no standing in formal mineral nomenclature; there is no IMA approval or real-world occurrence beyond narrative contexts. See also: minerals, pegmatites, mineralogy in fiction.