Black Obsidian is a smooth, glass-like stone with a shiny, reflective surface. It has a Mohs hardness scale rating of 5.5. Obsidian, is not technically a crystal. It is, however, an igneous stone. Igneous stones and crystals are formed from cooled volcanic lava, either from active volcanos or from lava in the center of the earth's crust.
Sometimes, volcanic lava cools quickly, which does not allow crystals to form. When this happens, a smooth, volcanic glass-like rock is formed. This type of rock is called a mineraloid. Black Obsidian is a mineraloid with a rich, deep color and smooth surface that is somewhat mirror-like..
Black Obsidian is a very protective stone, and is excellent for removing negativity. It is also excellent protection against psychic attacks. In particular obsidian protects the gentle from abuse, and is used to cut attachment cords to release one. It is a very grounding stone, and very healing. Obsidian is also an excellent manifestation stone. Physically it is said to benefit the stomach, intestines, muscle tissue, and can rid one of bacterial or viral infections. It sharpens and focuses internal and external vision, and helps get in touch with buried issues before they explode. Note that healing crystal meanings are spiritual supports to healing and are not prescriptions or healthcare information. Obsidian is related primarily to the root chakra, though differing colors may relate to different chakras as well.