Obsidian is an excellent grounding stone and provides for a connection from the base of the spine to the heart of the Earth.
It is an excellent protective stone, stabilizing internal and external energies and gently protecting one from that which could bring physical and/or emotional harm.
It provides a shield against negativity, transforming negative vibrations within an environment.
It is quite useful in healing, providing both the healer and subject with clarity with respect to both the cause and the amelioration of the disease.