Obsidian is formed when volcanic lava comes into contact with water; this forces it to cool so quickly that it doesn't have time to crystallize resulting in a stone with a shiny, glassy texture.
Black Obsidian is an extremely powerful and fast acting stone, and should be used with caution for Crystal Healing. It can bring negative emotions and unpleasant truths rushing to the surface, which have to be confronted before peace can return. Many people find Obsidian's effects overwhelming and prefer to use a gentler stone. Black Obsidian is a very protective stone. It is said to form a shield against negativity and to absorb negative energies from the environment. Because of this it should be cleansed regularly in running water.
Place Black Obsidian on the Base Chakra for grounding. In healing Obsidian is believed to reduce the pain of arthritis, to help joint problems and to ease cramp. It is also said to aid digestion.
Color: dark green to dark brown and black, also can show sheens of gold or green, yellow, blue and/or purple coloration. Sometimes with white inclusions.
Transparency: Obsidian is translucent in any stone of appreciable size.
Crystal System: Does not apply because obsidian is amorphous.
Habits: Compact nodules or as massive layers between other volcanic rocks.
Hardness: 5 - 5.5
Specific Gravity: 2.6
Best Field Indicators: Color, fracture, flow bubbles, softness, association with other volcanic rocks and lack of crystal faces.