Fire Obsidian - High Grade Lapidary Slab – Glass Buttes OR – Iridescent For Sale

Fire Obsidian Rough Slab — Glass Buttes, Oregon
This is a natural, unpolished fire obsidian slab sourced from the Glass Buttes region of central Oregon — the only known location in the world where true fire obsidian is found. The piece weighs 91 grams and measures approximately 86 mm x 92 mm and from 6 mm to 10 mm in thickness.
Fire obsidian gets its color play from an exceptionally thin film of nano-scale magnetite crystals on and just beneath the surface. These crystals cause optical interference that produces vivid, shifting color — similar in mechanism to labradorescence, but unique to this material. This piece has multiple bands of irridescent magnetite. The bands of magnetite are very bright with intricate patterns and a lot of color shift. All of the colors in the spectrum are visible in this slab's iridescent bands. The bands run through the half of the slab with some hidden from view.
The obsidian itself has no noticeable inclusions or cristobalites making this a truly high grade slab.
Photos are wet, taken in direct sunlight — this is the standard way to preview fire obsidian rough, as wetting the surface mimics the optical effect of a polished face and gives the most accurate preview of what's inside. The dry piece will appear darker and more muted until worked.
This piece is unpolished and unshaped. It is sold as-is, as a natural slab, and is well-suited for:
Lapidary cabochon work
Freeform or sculptural cutting
Collector display as rough
Study specimen
Fire obsidian is notoriously challenging to cut and polish due to its glassy fracture — but the results for skilled lapidaries are exceptional.
Shipped securely wrapped and padded.