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.
Is this gastrolith?
3-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Read the lusterHold the specimen under a strong light. Gastrolith typically shows a variable luster.
- 2Match the color rangeCompare against the expected color range: variable, brown, gray, black, red, tan.
- 3Look at form & habitTypical habit: rounded, polished surface.
All properties
- Luster
- Variable
- Transparency
- Opaque
- Crystal habit
- Rounded, Polished Surface
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Scientific Research, Paleontological Study
- Host rock
- Sedimentary Deposits
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
Look in sedimentary deposits country, the host setting where gastrolith typically forms. If you start seeing dinosaur bones, fossilized teeth in float, you are in the right ground. Field specimens usually show a rounded, polished surface habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wyoming. Start trip planning there.
Common questions
How do you identify gastrolith?+
Where is gastrolith found?+
Can I find gastrolith in the United States?+
What minerals are found with gastrolith?+
What kind of rock does gastrolith form in?+
What is gastrolith used for?+
Find gastrolith on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
