Thermium

Thermium is a late-game refined metal used when extreme heat resistance is required. It is produced from Niobium and Tungsten in the Molecular Forge, and it is notable for its very high overheat tolerance, which makes it one of the most important construction materials for high-temperature industrial builds.

Thermium is created from 5 kg Niobium + 95 kg Tungsten = 100 kg Thermium. The reverse conversion is also useful: the Metal Refinery can convert Thermium into Niobium at a 1:1 mass ratio, and the Rock Crusher can break 100 kg Thermium into 50 kg Niobium and 50 kg Sand. Because of this, Thermium can serve as an intermediate way to reclaim Niobium once enough Tungsten has been gathered. Since the refinery conversion returns Niobium directly, even a small amount of Niobium from a Niobium-bearing asteroid can be enough to start a larger Thermium production chain.

Its main gameplay advantage is that it increases the overheat temperature of buildings constructed from it by 900 °C. This makes Thermium especially valuable for machinery that must operate in very hot environments, where ordinary metals would fail long before the surrounding area becomes dangerous. It is often used for endgame infrastructure such as a Thermo Aquatuner running Super Coolant, or for builds like a sour gas boiler where nearby equipment must survive extreme temperatures.

Thermium also has special thermal and phase-change behavior:

• If melted, it becomes Liquid Niobium and Tungsten.
• The melt output is heavily split toward Tungsten: 95% Tungsten and 5% Liquid Niobium by mass.

That unusual composition means Thermium is not just a top-tier building material, but also a way to store and move resources between late-game production steps. Its behavior makes it part of the late-game metal economy rather than a simple one-way crafting material.

In practical use, Thermium is most valuable when the player has already moved past basic colony survival and is building compact, heat-intensive industrial systems. It is generally overkill for ordinary machinery, but indispensable when a build needs to run reliably at temperatures that would destroy steel or other common construction materials.