The sixth chakra, Ajna, is in the area of the third eye, which is found in the space between the eyebrows. It encompasses the pituitary gland, eyes, head, and lower part of the brain. An invisible yet powerful third eye, this is your center of intuition. A spiritual chakra, which means “beyond wisdom,” Ajna leads you to an inner knowledge that will guide you if you let it. An open sixth chakra can enable clairvoyance, telepathy, lucid dreaming, expanded imagination, and visualization. (source)
Some crystals that we carry that my help you balance your Third Eye Chakra are Sodalite, Amazonite, and Blue Lace Agate.