Obsidian Gemstone Beads

Frequently asked questions

• Is obsidian a crystal or glass?

  Obsidian is volcanic glass — amorphous silica with no crystal structure. It forms when felsic lava cools so rapidly that crystals never have time to grow, leaving a dense, glossy, glass-like material. This is why obsidian polishes to a mirror-like luster and breaks with the characteristic curved (conchoidal) fracture that made it a prehistoric tool material. Mineralogically it sits in its own category — not a mineral by strict definition, but a naturally-occurring volcanic product.
• Where does obsidian come from?

  Obsidian forms at volcanic deposits worldwide wherever silica-rich (felsic) lava cools too fast for crystallization. Mexico — particularly the Pachuca and Jalisco regions — is the dominant commercial source for the bead trade. Other significant deposits include the western United States (Oregon, California, Idaho, Arizona), Iceland, Italy, Armenia, Russia, Japan, and Indonesia. Origin should be disclosed where the supplier has disclosed it — ask before buying if a strand doesn't specify.
• What's the difference between obsidian and onyx?

  They look similar polished but are different materials. Onyx is microcrystalline quartz (chalcedony family) at Mohs 6.5–7 — a banded variety of quartz, often dyed jet-black for the bead trade. Obsidian is amorphous volcanic glass at Mohs 5–5.5 — softer, more brittle, and showing conchoidal fracture rather than the granular break of onyx. In a finished piece, obsidian carries a slightly more reflective glassy luster; onyx reads as a denser opaque black.
• What are the sub-varieties of obsidian?

  The named sub-varieties come from what happened inside the cooling glass. Black obsidian is the base form. Snowflake obsidian has white-to-gray cristobalite spherulites from slow devitrification. Mahogany obsidian has reddish-brown iron oxide banding. Rainbow obsidian shows iridescent color bands from light interference off nanoscale magnetite layers. Gold sheen and silver sheen obsidian show a metallic-looking shimmer from light reflecting off aligned gas bubbles or mineral inclusions. Each sub-variety is its own sub-collection in Dakota's catalog.
• How durable is obsidian for daily wear?

  Obsidian is Mohs 5–5.5 — softer than quartz-family stones (agate, jasper, chalcedony) and softer than most beads it shares a strand with. It is also brittle and fractures conchoidally, so sharp impact can chip an edge or split a bead. For finished pieces, obsidian works well in earrings, pendants, and necklaces where impact is rare; in rings or heavy-wear bracelets it benefits from careful design and protective placement. Standard cleaning is soft cloth with mild soap — avoid ultrasonics and steam.