Chemistry and astrology were related in alchemy. There were seven planetary metals that were ruled by corresponding celestial bodies. Often the symbols for the planets and the metals were the same.
- gold or aurum was dominated by Sol, the sun
- silver or argentum was dominated by Luna, the moon
- copper or cuprum was dominated by Venus
- iron or ferrum was dominated by Mars
- tin or stannum was dominated by Jupiter
- mercury (quicksilver) or hydrargyrum was dominated by Mercury
- lead or plumbum was dominated by Saturn
Uranus, Neptune, and Pluto had not been discovered at the time of the alchemists. Modern alchemists sometimes consider the symbols for these planets to represent the metals uranium, neptunium and plutonium.