Limum

Limum is a fictional mineral that appears in science fiction and worldbuilding literature. It is typically described as a lithium-rich silicate with metallic luster and unusually high thermal stability, making it a candidate for advanced materials in speculative technologies.

Origin and name: The term limum derives from the fictional Limum Valley, a setting used by several authors, with the mineral subsequently incorporated into various narratives. Descriptions vary by work, but most portray its composition as a lithium-iron-manganese silicate with trace rare earth elements.

Physical properties: In common depictions, limum crystallizes in a monoclinic system, forms prismatic crystals, and ranges in color from blue-gray to black. Reported hardness is around 5.5–6 on the Mohs scale; density approximately 3.3–3.6 g/cm3. It is described as having a faint iridescent sheen and weak paramagnetism due to iron content.

Occurrence and formation: In fiction, limum forms in subduction-zone metamorphic environments or in asteroid- or Martian-type rocks where fluids interact with silicate minerals under high pressures. Some authors place limum in hydrothermally altered basalts or ultramafic rocks.

Uses and significance: In speculative settings, limum is envisioned for high-temperature ceramics, radiation shielding, lightweight structural components, and experimental quantum materials. Its hypothetical properties—thermal stability, hardness, and electronic characteristics—drive its imagined applications.

See also: Mineral; Worldbuilding; List of minerals.