Obsidian is not considered an actual mineral but instead volcanic lava that has cooled into black volcanic glass. It's primarily made of silica that may also include (albeit uncommon) quartz inclusions. Found throughout the world where there is volcanic activity, Obsidian gains its characteristic solid black color largely due to the iron and magnesium found within it. It is said that Obsidian is a powerful protective "stone" that absorbs negative energy and lends it's wearer to be more compassionate and absolved of mental stress and tension.