No metal is completely immune to rust, but some are much more resistant than others. Gold is considered the most rust-resistant metal. It's highly unreactive and doesn't readily oxidize in air or water.

Here's why:

* Chemical Inertness: Gold is very low on the reactivity series of metals, meaning it doesn't easily react with other substances.

* Noble Metal: Gold is considered a "noble metal" due to its resistance to corrosion.

However, even gold can corrode under specific conditions, like exposure to strong acids or very high temperatures.

Let me know if you'd like to learn more about rust and its prevention!