lahustum

Lahustum is a fictional mineral coined for use in speculative geology and science fiction worldbuilding. In this fictional corpus, lahustum is a dark olive-brown to black silicate mineral that often displays a metallic to submetallic luster and forms as relatively coarse grains within metamorphosed ultramafic rocks.

It is described as crystallizing from high-temperature hydrothermal fluids during granulite facies metamorphism, usually in association with garnet, orthopyroxene, and corundum; trace hafnium and rare earth elements are sometimes noted.

Physical properties commonly attributed to lahustum in the literature include a Mohs hardness of about 6 to 6.5, a monoclinic crystal system, imperfect cleavage, and a color range from olive-brown to black with a pale brown streak; luster ranges from metallic to submetallic.

Etymology and discovery: The name honors the fictional explorer Lahust of the Valle region. First described in the fictional Exilon-3 Geology Initiative literature in 2142, the type locality is the Lahust Massif on Exilon-3.

Uses and significance: Given its fictional status and rarity, lahustum has no real-world industrial applications. In narrative contexts, it is sometimes imagined as a high-temperature ceramic constituent or as a pigment, and it is used as a proxy indicator for specific metamorphic conditions.