Iridium

Iridium is a refined metal with no corresponding ore form, but it still carries the metal ore tag. Like other high-end construction metals, it raises a building’s overheat temperature by 500°C, making it a strong choice for machinery that must survive extreme heat. In many cases it serves as a superior substitute for steel, since steel only raises overheat temperature by 200°C and also has a slightly lower melting point.

Its standout trait is that it can push certain buildings above 600°C overheat thresholds, which is especially important for setups such as phase oil refining and crude oil cracking. Compared with niobium or thermium, Iridium is available earlier in the game, although it cannot currently be mass-produced through industrial processes.

Iridium also has one of the best thermal performance profiles in the game. It has the third-highest solid thermal conductivity, lower only than thermium and aluminum, so it is well suited to builds that need efficient heat transfer. This makes it useful in high-temperature industrial systems, heat exchangers, and other setups where rapid conduction matters.

It is also one of the best materials for radiation-related construction. Iridium has the highest radiation absorption factor in the game at 0.88, and when used for tiles it provides up to 70.4% radiation resistance. For that reason, it is especially effective for building radiation shielding structures. Because materials with high radiation resistance often also have comparatively lower melting points, Iridium can be an ideal choice for reactor protective walls.

As a building material, Iridium also grants a +20% Decor bonus, the same value provided by several other high-end decorative materials. This makes it useful not only for functional industrial construction, but also for rooms where decor matters.

Iridium can also be used as food for Plug Slugs and their variants:

• Standard Plug Slugs consume Iridium at a rate of 60 kg/cycle and excrete it at 3 kg/cycle.
• Other variants consume Iridium at 30 kg/cycle and excrete it at 1.5 kg/cycle.

Overall, Iridium is a premium late-game material with an unusual combination of heat tolerance, strong thermal conductivity, radiation shielding potential, and decor value. Its main drawback is scarcity, since it is not something that can be mass-produced easily, so it is best reserved for critical infrastructure rather than routine construction.