Obsidian is a light, shiny black stone created when a volcanic flow is cooled very quickly, into what geologists call, "volcanic glass". Pure black obsidian is called "Apache Tears" and when it features a colored sheen, such as these beads, it is called "Rainbow Obsidian". Obsidian has long been fashioned into knives and arrowheads, but Obsidian also polishes to a shiny mirror surface. This mirror surface has been attributed to many spiritual uses by ancient civilizations. Used by the Aztecs in creating images of the God Tezcatlipoca, (which means "shining mirror"). To them the stone was sacred, called "iztli" or "teotetl" meaning "divine stone." Because of its mirror-like polish, this stone is often associated with divining the future in its clear, glassy surface. All Obsidian is considered extremely protective. Obsidian is most commonly thought to be a gemstone that reflects back to us (mirrors) our own flaws, in no uncertain terms, for Obsidian energy is not thought to be subtle energy. It is said to induce visions and dreams that reveal to us our own part in the difficult areas of our lives.