Judging quality
The fire moves under the surface as the stone is rotated, unlike surface-reflective imitations. Freeform, bumpy cabochon shapes are normal because the cutter follows the botryoidal layers.
Chalcedony
Fire Agate
Chalcedony containing microscopically thin layers of iron oxide that create iridescent fire — reds, greens and golds — trapped inside the stone. Cutting it is a specialist skill: the cutter must chase the fire layer without going through it.
Care
Hard and stable. Water only; no abrasives, which would cut the thin fire layer.
History & lore
Found only in a limited zone of the Sonoran and Chihuahuan deserts, formed in hot springs about 25 million years ago.
Cultural history, recorded as tradition rather than as medical or scientific claim.
Common questions about Fire Agate
- What is Fire Agate?
- Chalcedony containing microscopically thin layers of iron oxide that create iridescent fire — reds, greens and golds — trapped inside the stone. Cutting it is a specialist skill: the cutter must chase the fire layer without going through it.
- How hard is Fire Agate and what is it made of?
- Fire Agate is a Chalcedony-family mineral with the composition SiO2 with iron oxide films. It crystallizes in the trigonal system and rates 6.5-7 on the Mohs hardness scale. It occurs in brown, red, iridescent, emerald green.
- Where does Fire Agate come from?
- Notable localities for Fire Agate include Arizona, USA, Mexico (Chihuahua, Aguascalientes).
- How do you tell good Fire Agate from filler?
- The fire moves under the surface as the stone is rotated, unlike surface-reflective imitations. Freeform, bumpy cabochon shapes are normal because the cutter follows the botryoidal layers.
- How do you care for Fire Agate?
- Hard and stable. Water only; no abrasives, which would cut the thin fire layer.
See it in person
Photographs only go so far
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.