Item from Project Hail Mary by Andy Weir
An Eridian super-material made of pure xenon — the strongest substance either civilization has ever produced, until the cure for extinction learned to eat through it.
Xenonite is Eridian engineering made physical. A pure-xenon compound that is supremely strong, hard, and heat-resistant — it withstands the 29-atmosphere pressure of Erid's environment, survives interstellar radiation, and forms the structural backbone of everything Rocky builds. The Blip-A is primarily xenonite. The connecting tunnel to the Hail Mary is xenonite. Rocky's repairs and modifications are xenonite. The material becomes a critical plot point when engineered Taumoeba-82.5 demonstrates the ability to pass through xenonite barriers — something the natural strain cannot do. This means the nitrogen-resistant Taumoeba that Grace and Rocky bred to save both civilizations could also consume Rocky's fuel supply and dissolve his ship's hull. The cure becomes a threat, and the strongest material in the story becomes a vulnerability.
A dark, dense material with the look of metal but the composition of a noble gas compound. Impossibly hard and heat-resistant. Forms the hull of the Blip-A and the connecting tunnel between the two ships. The surface is smooth and featureless — engineered at a molecular level that human materials science can't replicate.
Also known as: Xenonite