Obsidian is a natural volcanic glass formed after eruptions from lava flow that cools too quickly to crystallise. For this reason it is a mineraloid, and not technically a true crystal as it has no repeating crystal structure. The use of Obsidian dates back to the Stone Age, and it has been used for thousands of years in weaponry and rituals. The Mesoamericans and the Mayans polished it into mirrors for use in contacting spirits and as portals to other realms. There have more recently been bright blue and green transparent 'obsidians' seen on the market - these are in fact just manmade coloured glass. Genuine varieties of Obsidian include Black Obsidian, Mahogany Obsidian, Snowflake Obsidian, Rainbow Obsidian, Gold and Silver Sheen Obsidian, and more rarely Velvet Obsidian and Fire Obsidian. Specific mines have also been known to produce special colours of Obsidian, such as the Pink Lady Mine in northern California.

Each variety of Obsidian has their own unique metaphysical properties. Black Obsidian serves as a powerful source of insight and protection, guarding against negative influences and facilitating a deeper understanding of the self. Gold Sheen Obsidian takes on a cleansing role, purifying the aura and promoting spiritual clarity. Rainbow Obsidian brings forth hope and renewed energy, infusing life with optimism and rejuvenation. Mahogany Obsidian's grounding nature establishes a strong connection to the Earth, fostering stability and balance. Snowflake Obsidian serves as a tempering force, helping to quell anger and resentment, ultimately promoting emotional healing and harmony.