Black tourmaline crystal is a mineral that is usually black or dark in color and is known as the "Stone of Protection." Black tourmaline is known for its ability to protect against negative energies and electromagnetic radiation. It is believed to create a protective shield around the body and to neutralize negative energies and psychic attacks. It is also said to help release stress and tension and promote inner peace. Black tourmaline is associated with the root chakra and is believed to help ground and stabilize the body and mind. It is often used in meditation and healing practices to cleanse and purify the energy field. It can also be placed near electronic devices or worn as jewelry to protect against harmful electromagnetic fields.