A gastrolith is a stone swallowed by an animal, such as a dinosaur or a modern bird, to grind food in the gizzard and aid digestion. Look for the distinctive high-polish surface created by gastric churning; specimens are often found in association with articulated dinosaur skeletons.
Luster
Variable
Transparency
Opaque
Is this gastrolith?
4-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Name the organismDecide what left the fossil before worrying about the rock. Organism: Stones swallowed by animals such as sauropod dinosaurs.
- 2Check the preservationPreservation: Swallowed rock, often highly polished. That controls the weight, the hardness and how the piece takes a polish.
- 3Read the lusterHold the specimen under a strong light. Luster: variable.
- 4Match the color rangeCompare against the expected color range: variable, brown, gray, black, red, tan.
All properties
- Luster
- Variable
- Transparency
- Opaque
- Rarity
- Uncommon
- Uses
- Collector, Scientific research, Paleontological study
- Host rock
- sedimentary deposits
- Organism
- Stones swallowed by animals such as sauropod dinosaurs
- Preservation
- Swallowed rock, often highly polished
Where rockhounds find gastrolith
4 mapped spotsClassic worldwide localities
- Morrison Formation, USA
- Glen Rose Formation, USA
- Winton Formation, Australia
- Gobi Desert, Mongolia
Field-hunting tip
Where it forms: sedimentary deposits. If you start seeing dinosaur bones, fossilized teeth in float, you are in the right ground. In the U.S., the densest reported localities are in Wyoming. Start trip planning there.
Common questions
How do you identify gastrolith?+
Organism: Stones swallowed by animals such as sauropod dinosaurs. Preservation: Swallowed rock, often highly polished. Luster: variable. Common colors include variable, brown, gray, black.
Where is gastrolith found?+
Notable localities include Morrison Formation, USA; Glen Rose Formation, USA; Winton Formation, Australia; Gobi Desert, Mongolia.
Can I find gastrolith in the United States?+
RockHoundR maps 4 gastrolith rockhounding spots across 1 U.S. states. The top states are Wyoming.
What minerals are found with gastrolith?+
Gastrolith commonly co-occurs with dinosaur bones, fossilized teeth. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does gastrolith form in?+
Where it forms: sedimentary deposits. Working float back to the host body is the standard way to chase a fresh occurrence.
What is gastrolith used for?+
Gastrolith is used in collector, scientific research, paleontological study.
Find gastrolith on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
