A nodule is a rounded, irregular mass or concretion formed by mineral precipitation around a central nucleus within sedimentary rock. Collectors prize it for what may be inside: a quartz or chalcedony-lined geode, fossilized material, or an unusual crystalline structure. It commonly weathers out of softer host rock such as chalk beds or shale.
Is this nodule?
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 nodule
Minerals reported to co-occur with nodule. 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
Where rockhounds find nodule
10 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, the host setting where nodule 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, Utah. Start trip planning there.
Common questions
Where is nodule found?+
Can I find nodule in the United States?+
What minerals are found with nodule?+
What kind of rock does nodule form in?+
What is nodule used for?+
Find nodule on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
