Gold

Gold (Au), element 79.

Shares many properties with copper and silver.

Highly conductive and ductile. Can form atom-thin wires. Critical for corrosion-resistant electronics, especially in humid environmnents.

Also useful for shielding spacesuits and spacecraft against heat.

Rare—tends to sink to the core of planets during formation. If you cannot access the core of the planet, search for surface deposits formed by bacterial accumulation.