RocksdayFire Agate
Fire Agate is a mineral (SiO₂) with a Mohs hardness of 6.5–7 and a vitreous to waxy luster, usually brown, orange, red or green.
Brown chalcedony layered with thin films of iron oxide that flash red, green and gold when the stone is tilted.
How to identify fire agate
- Brown or orange body color with patches of iridescence.
- Waxy, and hard enough to scratch glass.
- The color sits in curved layers, not in round opal dots.
Often confused with
OpalPrecious opal's color is in a pale or dark body as pinpoints, and opal is much softer.
Compare side by side
Where it's found
- Slaughter Mountain, Arizona
- Deer Creek, Arizona
- Aguascalientes, Mexico
- Chihuahua, Mexico
Uses
Cabochons.
Rock tumbling
Can be tumbled with care. The color layer is thin — aggressive grit can cut through it.
Did you know?
The flash comes from iron oxide films only a few wavelengths of light thick, not from opal's stack of silica spheres.
Fire Agate FAQ
What is fire agate?
Fire Agate is a mineral (SiO₂) with a Mohs hardness of 6.5–7 and a vitreous to waxy luster, usually brown, orange, red or green. Brown chalcedony layered with thin films of iron oxide that flash red, green and gold when the stone is tilted.
How do you identify fire agate?
Brown or orange body color with patches of iridescence. Waxy, and hard enough to scratch glass. The color sits in curved layers, not in round opal dots.
How hard is fire agate?
Fire Agate has a Mohs hardness of 6.5–7. Fire Agate scratches glass, and a steel knife can't scratch it.
Where is fire agate found?
Notable localities include Slaughter Mountain, Arizona; Deer Creek, Arizona; Aguascalientes, Mexico; and Chihuahua, Mexico.
What is fire agate used for?
Cabochons.
Can you tumble fire agate?
Yes, with care. The color layer is thin — aggressive grit can cut through it.
What is fire agate often confused with?
Fire Agate is most often confused with Opal and Agate. Precious opal's color is in a pale or dark body as pinpoints, and opal is much softer. Ordinary agate is banded but doesn't flash rainbow colors.
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