Theralis

Theralis is a fictional mineral frequently referenced in science fiction and tabletop role-playing settings. It is described as a rare, heat-resistant silicate with exceptional thermal stability and a reversible phase transition that stores and releases heat, making it valuable for high-temperature engineering and thermal management.

In common in-universe lore, Theralis was first described in 2142 by researchers from the Solarium Institute during a survey of ultramafic rocks on the outer moon Ixion. The mineral is typically found as coarse nodules embedded in host rocks and is often exposed by micrometeoroid weathering.

Theralis crystallizes in a dense, tetragonal to orthorhombic lattice and is composed primarily of iron, magnesium, aluminum, silicon, and oxygen. It has a high melting point and density, low thermal expansion, and exhibits a reversible phase transition near high temperatures. During heating, the transition absorbs heat; during cooling, it releases heat, effectively functioning as a thermal battery.

Geologically, Theralis forms in high-grade metamorphic or alkaline ultramafic environments where intense pressure and temperature drive phase separation. It is commonly associated with serpentines, olivine-rich rocks, and rare-earth-bearing minerals.

Applications within its fictional universe include heat shields for hypersonic craft, thermal energy storage units in power systems, and components of compact reactors. Processing requires advanced smelting and controlled crystallization, and commercial deposits are described as scarce and geographically clustered, leading to restricted trade.

Ethical and strategic considerations accompany Theralis in fiction, with export controls and research partnerships shaping its availability. The mineral appears in several works of science fiction, where its properties are used to explore themes of energy security and technological dependence.