Iris Agate is a rare variety of chalcedony characterized by extremely fine, parallel banding that causes the diffraction of light into prismatic colors when sliced thin and backlit. Collectors look for high translucency and distinct, sharp color separation when viewing a light source through the polished slab. It is most famously sourced from specific localities in the Pacific Northwest of the United States.
Is this iris 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 iris agate with a known reference. Iris 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. Iris Agate leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Iris Agate typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, brown, rainbow-iridescent.
- 5Look at form & habitCrystal system: trigonal. Typical habit: banded, microcrystalline, massive.
Often confused with
Iris Agate vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside iris agate
Minerals reported to co-occur with iris 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
- 2.6-2.65 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Banded, Microcrystalline, Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Lapidary
- Host rock
- Volcanic Vesicles and Rhyolite Cavities
- Typical price
- $20-200 per specimen depending on slice quality and spectral intensity
Where rockhounds find iris agate
1 mapped spotsClassic worldwide localities
- Oregon (USA)
- Montana (USA)
- Mexico
- Indonesia
Field-hunting tip
Look in volcanic vesicles and rhyolite cavities country — that is the host setting where iris agate typically forms. If you start seeing quartz, calcite, zeolites in float, you are in the right ground. Field specimens usually show a banded, microcrystalline, massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Idaho — start trip planning there.
Common questions
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Find iris agate on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
