Obsidian is volcanic glass formed when lava cools too quickly to crystallize, used since the Paleolithic for both tools and amulets. Spiritually, it is considered a powerful 'mirror stone' — reflecting negative energy back to its source rather than absorbing it. This article covers obsidian's use in Aztec divination (Tezcatlipoca's smoking mirror), its modern crystal-healing applications for grounding, shadow work, and psychic protection, and how to care for and recharge an obsidian bracelet through moonlight, smoke cleansing, or burying briefly in earth.