Nodules are rounded, irregular masses or concretions formed by the mineral precipitation around a central nucleus within sedimentary rocks. Collectors often prize them for the surprises found inside, such as quartz or chalcedony-lined geodes, fossilized material, or unique crystalline structures. They are commonly weathered out of softer host rocks like chalk beds or shale layers.
Is this nodules?
2-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Match the color rangeCompare against the expected color range: gray, brown, black, white.
- 2Look at form & habitTypical habit: nodular.
Often found alongside nodules
Minerals reported to co-occur with nodules. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Crystal habit
- Nodular
- Rarity
- Common
- Uses
- Collector, Lapidary
- Host rock
- Sedimentary Strata Such as Limestone, Chalk, Or Shale
- Typical price
- $5-50 depending on contents and size
Where rockhounds find nodules
8 mapped spotsClassic worldwide localities
- United Kingdom
- United States
- France
- Germany
- Poland
Field-hunting tip
Look in sedimentary strata such as limestone, chalk, or shale country — that is the host setting where nodules typically forms. If you start seeing chalcedony, calcite, pyrite in float, you are in the right ground. Field specimens usually show a nodular habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Arizona, Nevada, Washington — start trip planning there.
Common questions
Where is nodules found?+
Can I find nodules in the United States?+
How much is nodules worth?+
What minerals are found with nodules?+
What kind of rock does nodules form in?+
What is nodules used for?+
Find nodules on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
