Agate is a variety of microcrystalline quartz characterized by its distinct, often concentric banding or inclusion patterns. It is most commonly found filling cavities in volcanic rock, and collectors often hunt for them as rounded nodules known as thunder eggs or geodes.
Is this 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 agate with a known reference. 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. Agate leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Agate typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: white, gray, blue, brown, red, yellow, green, black, multicolored.
- 5Look at form & habitCrystal system: trigonal. Typical habit: banded, botryoidal, nodular, massive.
Often confused with
Agate vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside agate
Minerals reported to co-occur with 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
- 2.6-2.7 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Banded, Botryoidal, Nodular, Massive
- Cleavage
- None
- Fluorescence
- None to Weak Fluorescent
- Rarity
- Common
- Uses
- Lapidary, Decorative, Collector, Jewelry
- Host rock
- Volcanic Cavities, Hydrothermal Veins, Sedimentary Deposits
- Typical price
- $5-50 for small specimens, $100-500+ for large polished slices or rare varieties
Where rockhounds find agate
374 mapped spotsClassic worldwide localities
- Brazil
- USA (Oregon, Montana, Michigan)
- Uruguay
- Germany
- Mexico
- India
U.S. states with agate
Each link opens a state-specific list of mapped rockhounding spots that produce agate.
- Oregon35 spots
- New Mexico33 spots
- Utah24 spots
- Wyoming23 spots
- Washington21 spots
- Texas20 spots
- Nebraska14 spots
- North Carolina13 spots
Field-hunting tip
Look in volcanic cavities, hydrothermal veins, sedimentary deposits country — that is the host setting where agate typically forms. If you start seeing quartz, calcite, zeolites in float, you are in the right ground. Field specimens usually show a banded, botryoidal, nodular, massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Oregon, New Mexico, Utah — start trip planning there.
Common questions
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Find agate on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
