Stone library / Glass, Organic & Extraterrestrial / Natural GlassObsidianEverything you need to know about obsidian: what it is, where it comes from, how to spot treated stones, and how to wear and care for it.Illustrative Obsidian image. Appearance alone cannot confirm the exact material, treatment, origin, or value of a specific piece.What is obsidian?Obsidian is a mineral variety with chemical formula SiO₂ (amorphous — volcanic glass, no crystal structure). It has a Mohs hardness of 5–5.5, density of approximately 2.35–2.6 g/cm³, and refractive index of 1.48–1.51.What gives it its color?Rapid cooling of silica-rich lava prevents crystallization. Iron and other minerals create color variants.Where does it come from?Major sources include Mexico, USA, Iceland, Japan, Italy, Turkey.Treatments and how to spot themGenerally untreated. 'Rainbow obsidian' shows iridescence from microscopic inclusions. 'Snowflake obsidian' has cristobalite spherulites.Important: Visual clues such as inclusions, color patterns, or surface features can provide preliminary observations, but they cannot replace refractive index, specific gravity, microscopic examination, and laboratory testing for a definitive identification. Treat visual clues as starting points, not final answers. Jewelry and care tipsWith hardness 5–5.5, obsidian is suitable for rings, pendants, earrings, and bracelets. Clean with warm soapy water and a soft cloth. Avoid ultrasonic cleaners unless the stone is known to be fracture-free. Store separately from harder gemstones.Cultural beliefs and symbolismObsidian carries cultural meaning across many traditions — these are folkloric and cultural traditions, not scientifically verified properties. Its associations vary by culture, and its use in astrology, chakra, or feng shui contexts should be understood as cultural expression rather than factual claims.What affects its value?Price is determined by color saturation, clarity, cut quality, and size. Before buying: ask the seller to confirm the material identity, treatment status, dimensions, and return policy in writing.Use this guide as a starting pointFor a costly or disputed stone, ask for species, treatment, and origin information in writing. An independent laboratory report is stronger evidence than a marketing phrase.Return to Glass, Organic & ExtraterrestrialPrevious guideNephrite JadeNext guideOpalSources: GIA reference and the GemVerity editorial method. This is an educational guide, not a gemological identification report. Cultural beliefs described above are folkloric traditions, not scientific guarantees.