Below are the best books we could find on Crystals.

Crystals are fossilized minerals that are used as complementary tools for mental, emotional, physical, and spiritual healing purposes. Crystals are present in various healing traditions, and can be seen as sources of energy, amplifiers or dampeners of cosmic or spiritual energies, or as sacred elements of rituals. Crystals can be used in physical arrangements, worn on the body, or used as infusions for tinctures.