Gold is also used in very small quantities in the medical world, for example in the treatment of certain diseases. Gold is also used in aviation and as a pigment for windows. The coating of gold reflects the sun's rays, so buildings with such windows need less cooling in the summer. For astronauts, the gold coating in the window of the helmet provides protection from the force of the sun.
Gold is used in aerospace
But also for special heat-resistant windows
Source: Geology