Obsidian is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is rich in the lighter elements such as silicon, oxygen, aluminum, sodium, and potassium. Obsidian is hard, brittle, and amorphous with sharp edges when fractured. Hence, it was used to manufacture cutting and piercing tools. Black Obsidian is regarded as a powerful spiritual cleanser and a shield against negative energies.