An oolitic agate is a distinctive chalcedony specimen featuring small, spherical ooids formed by concentric layers of silica around a nucleus. It occurs in sedimentary environments, showing a textured, bead-like surface that often reveals complex patterning when polished for lapidary use.
Is this oolitic 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 oolitic agate with a known reference. Oolitic 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. Oolitic Agate leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Oolitic Agate typically shows a waxy luster.
- 4Match the color rangeCompare against the expected color range: white, gray, brown, tan, red.
- 5Look at form & habitCrystal system: trigonal. Typical habit: botryoidal.
Often confused with
Oolitic Agate vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside oolitic agate
Minerals reported to co-occur with oolitic 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
- 2.65 g/cm³
- Streak
- White
- Luster
- Waxy
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Botryoidal
- Cleavage
- None
- Rarity
- Common
- Uses
- Lapidary, Collector, Decorative
- Host rock
- Sedimentary
Where rockhounds find oolitic agate
2 mapped spotsClassic worldwide localities
- Wyoming
- Utah
- Montana
- Nevada
Field-hunting tip
Look in sedimentary country, the host setting where oolitic agate typically forms. If you start seeing calcite, dolomite, quartz 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 Iowa, Oregon. Start trip planning there.
Common questions
How do you identify oolitic agate?+
Where is oolitic agate found?+
Can I find oolitic agate in the United States?+
What rocks look like oolitic agate?+
What minerals are found with oolitic agate?+
What kind of rock does oolitic agate form in?+
What is oolitic agate used for?+
Find oolitic agate on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
