Copper
Copper is a mineral of energy and mental agility. In legend, copper is said to be the metal of the God Hermes, who facilitates that mental agility, and quick wit.
Copper is an excellent conductor of energy, from electricity to the subtle energies emanating from higher planes, etc. Thus, copper is said to enhance and transmit thoughts, even over long distances.
Physically, copper is used to bringing in additional energies for all types of healing, treatment of arthritis, relieving pain of broken bones, sexual instability, and low energy.