Gold as a symbol of light

In Parshat Truma (Shmot 25:31) we read about the Menora:

You shall make a menora out of pure gold. The menorah must be made by hammering its form out of a solid piece of gold. Its base, its shaft, its cups, its knobs, and its flowers shall be of the same piece of gold.

The three types of metal that were used in the mishkan were gold (zahav), silver (kesef) and copper (nechoshet). Gold is of course the most precious.