Black Obsidian is a volcanic rock with a high silica content.

Hardness: 5 to 5.5
Chakra: Root
Elements: Earth, Fire 
Zodiacs: Scorpio, Sagittarius
Affirmation: "I release negative energy within and around me."

Black Obsidian is a very powerful protection stone that brings great mental strength. Forms a shield around one's aura, protecting one from negative energy and influences. Aids the release of addictive behaviors and dissolves emotional blockages.