As a healing stone, Black Obsidian is used for protection and has grounding properties. It reduces fantasies and helps clear subconscious blocks. It absorbs and disperses negativity and is a powerful healer for those attuned to it.
Obsidian is quickly cooled volcanic lava. It is a natural glass that is hard and brittle which is why it fractures with sharp edges. In the past it was used for piercing and cutting tools.