The Green River Formation around Kemmerer in southwest Wyoming preserves a 50-million-year-old lake bed packed with fossil fish, plants and insects. Collecting is not allowed on the public land of Fossil Butte National Monument, but several family-run private quarries nearby let visitors split the limestone and keep common fish.
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| Where | Private quarries near Kemmerer: American Fossil, Fossil Lake Safari, Tynsky’s, Ulrich’s and others |
|---|---|
| Cost | Half-day or full-day fee; tools usually provided |
| What you keep | Common fish such as Knightia and Diplomystus; rare finds usually stay with the quarry |
| Season | Late spring to early fall; book ahead in July and August |
| Rock | Green River Formation lake beds, about 50 million years old |
| Not allowed | Collecting in Fossil Butte National Monument |
Private quarries
- American Fossil
- Fossil Lake Safari
- In Stone Fossils
- Nature’s Treasures Fossil Fish Adventures
- Tynsky’s Fossil Fish
- Ulrich’s Fossil Gallery
Quarries charge by the half day or day and usually provide tools. Visitors keep common fish such as Knightia and Diplomystus; rare finds such as stingrays, birds, turtles or large predatory fish usually belong to the quarry. Ask about the policy when you book.
Fossil Butte National Monument
Fossil Butte National Monument protects the same formation. You cannot collect there, but its visitor center has some of the finest specimens and a research quarry program in summer where visitors help scientists but do not keep finds.
When to go
The quarries operate roughly from late spring to early fall, depending on weather; most are closed in winter. Book ahead in July and August.
Tips
Split the layers gently along their natural partings with a thin blade. Fish show up as dark brown outlines. Wrap finds in newspaper, and let the quarry staff stabilize fragile pieces.
Questions
Where can you dig fossil fish in Wyoming?
At private quarries near Kemmerer, such as American Fossil, Fossil Lake Safari, In Stone Fossils, Tynsky’s and Ulrich’s, which charge a fee and let you keep common fish.
Can you collect fossils at Fossil Butte National Monument?
No. Collecting is prohibited in the national monument.
When are the Kemmerer fossil quarries open?
Roughly late spring to early fall, depending on weather. Most close in winter.
Back to the Wyoming rockhounding guide · Rules by land type