What is an Obsidian Stone?

What is an Obsidian Stone?

Made from molten lava that cooled extremely fast and couldn't form into glass. Obsidian is a type of volcanic glass found throughout the world. Obsidian crystals are used throughout the world as a type of psychic cleansing. "The concept of darkness, and just like our ever-spinning planet and it phases of night and day, the human soul contains elements of light and dark." -Energy Muse

What is the Difference between Obsidian Stone and Lava Rock?