Fire agate is a stunning variety of chalcedony characterized by an iridescent, multi-layered internal play-of-color caused by thin inclusions of iron oxide minerals like goethite. It typically forms in botryoidal or stalactitic habits within volcanic cavities and requires careful lapidary work to reveal the hidden 'fire' layers.
Is this fire agate?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch fire agate with a known reference. Fire Agate sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Fire Agate leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Fire Agate typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: red, brown, orange, gold, green.
- 5Look at form & habitCrystal system: trigonal. Typical habit: botryoidal.
Often confused with
Fire Agate vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads waxy on Fire Agate and vitreous on Opal.
How to tell apart: Streak differs — Fire Agate leaves white, Iron Ore leaves reddish-brown to black; luster reads waxy on Fire Agate and metallic to submetallic on Iron Ore.
Often found alongside fire agate
Minerals reported to co-occur with fire agate. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SiO₂
- Mohs hardness
- 6.5-7
- Density
- 2.58-2.64 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Botryoidal
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Gemstone, Lapidary, Collector
- Host rock
- Hydrothermal Veins in Volcanic Rock
- Typical price
- $20-200 per gram for gem rough, $100-2000+ for finished cabochons
Where rockhounds find fire agate
4 mapped spotsClassic worldwide localities
- Arizona, USA
- Sonora, Mexico
- Aguascalientes, Mexico
- San Luis Potosí, Mexico
Field-hunting tip
Look in hydrothermal veins in volcanic rock country — that is the host setting where fire agate typically forms. If you start seeing chalcedony, quartz, goethite in float, you are in the right ground. Field specimens usually show a botryoidal habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Arizona, California — start trip planning there.
Common questions
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Find fire agate on the map
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