Mílth

Mílth is a term used in speculative fiction to denote a rare mineral or crystalline substance with distinctive properties. In many settings it refers to a solid material mined from specific geological formations, while in others it functions as a conceptual energy source or magical medium.

Physically, milth is described as a translucent, often iridescent crystal that emits light and stores energy. Descriptions vary, but common traits include high energy density, resistance to ordinary corrosion, and a tendency to fracture along regular facets that glow when energized.

Geologically, milth is placed in vein deposits within volcanically active regions or near tectonic boundaries. Mining is portrayed as hazardous because milth can release sudden surges of energy, trigger microquakes, or react violently to temperature changes.

In fiction, milth serves multiple roles: it powers devices and weapons, fuels runic or alchemical processes, and sometimes acts as a plot catalyst when a purer or rarer grade is encountered. Its scarcity and handling requirements shape economies and conflicts around its extraction and use.

Etymology and usage vary by world. The name milth is often linked to roots meaning light or energy in constructed languages, and it has been adopted by authors and game designers to convey rarity and potency. Across works, the concept of milth can be adapted to function as a physical material, a source of magical power, or a symbolic emblem of technology and mystique.