Abyssalite

Abyssalite is a naturally occurring solid element found in thick veins throughout the world, especially around hot underground regions. It is one of the game’s most important insulating materials because of its extremely low thermal conductivity, which makes it ideal for separating hot and cold areas, protecting machinery, and preserving biome temperatures during excavation.

Naturally spawning Abyssalite veins are generally at least two tiles thick. This thickness matters: a single tile does not insulate as effectively, because heat on both sides can still be exchanged through the tile. When digging through Abyssalite, especially near Volcanic Biomes, it is important not to thin the seam too much. Checking the Temperature Overlay helps avoid exposing nearby materials to dangerous heat.

Abyssalite has several unusual interactions with heat. Very hot natural Abyssalite can trigger flaking, which causes it to melt into Liquid Tungsten. Because flaking ignores its low thermal conductivity, hot Abyssalite can rapidly transfer enough heat to nearby substances to force state changes. This is especially relevant when Abyssalite borders extremely hot zones such as the Oily Biome or areas around magma. A hot Abyssalite tile can also instantly evaporate nearby liquids, making excavation around it hazardous.

Abyssalite can be used deliberately in industrial setups. One common application is refining Crude Oil into Petroleum early in the game by dripping it onto hot natural Abyssalite tiles, though this can overshoot into Sour Gas if the temperature is high enough. It is also useful in Petroleum Boiler designs, where flaking can help avoid State Change Hysteresis. In addition, Abyssalite is a key input for producing Insulite in the Molecular Forge.

• Molecular Forge recipe: 15 kg Isoresin + 80 kg Abyssalite + 5 Reed Fiber = 100 kg Insulite
• Abyss Bugs can eat Abyssalite.
• Abyssalite’s high-temperature phase change produces Liquid Tungsten, making it a route to tungsten production.
• Hot Abyssalite can be used to melt materials despite its very low thermal conductivity, because flaking bypasses normal insulation behavior.

Flaking itself has strict requirements. For partial melting, the parent must be a solid natural tile, the donor must be a gas, the parent must weigh more than 5 kg, and the donor must remain gaseous after giving off heat. For partial evaporation, the parent must be a liquid, with similar mass and adjacency requirements. In both cases, the parent and donor must end up adjacent after the game recalculates tile positions, and the child is created in 5 kg chunks at exactly 3 °C above the parent’s phase-up temperature.

Abyssalite is notable enough that players often build around it rather than remove it. Its role as a natural insulator, a heat-transfer edge case, and a source of Liquid Tungsten makes it one of the most strategically significant tiles in the game.