Mazonia-Braidwood State Fish & Wildlife Area (Mazon Creek Fossil Beds)
Braidwood, Illinois
siderite concretionsfern and seed-plant fossilstully monster fossilspyritemarine invertebrate fossils
State-designated locality · Free with permit
Mazonia-Braidwood State Fish & Wildlife Area (Mazon Creek Fossil Beds)
Mazon Creek is one of the world's great fossil deposits — soft-bodied Pennsylvanian plants and animals sealed inside ironstone concretions, including the Tully monster, Illinois' state fossil. Illinois DNR opens the old strip-mine spoil at Mazonia-Braidwood to collectors from March through September under a day permit you carry with you. The trick is patience: gather closed nodules and let a winter of freeze-thaw cycles in a bucket of water split them for you, because cracking them fresh usually destroys the fossil inside.
The card catalog
| What you can find | siderite concretions, fern and seed-plant fossils, tully monster fossils, pyrite, marine invertebrate fossils |
|---|---|
| Access | State-designated locality — Free with permit |
| Fees | No fee is stated. An IDNR day permit is required to collect fossils and may be obtained from the park office or the IDNR website. Excavations and collecting for commercial purposes are both prohibited, and a form for reporting what you found is available. |
| Season & hours | Fossil collecting is restricted to March 1 through September 30. The area is closed to fossil hunting October through February. |
| Kids | Family-friendly — Kids can pick nodules off spoil piles easily and the hunting needs no tools — which suits the rules, since excavating is prohibited. The hazards are real: this is reclaimed strip mine with uneven ground and deep water-filled pits, so keep children close and stay off the pit edges. |
| Official source | Illinois DNR |
| Last checked | Checked against its source August 16, 2026 |
Hours, fees, and access rules change. Verify with the operator or land agency before you go.
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Before you go
What does Mazonia-Braidwood State Fish & Wildlife Area (Mazon Creek Fossil Beds) cost?
No fee is stated. An IDNR day permit is required to collect fossils and may be obtained from the park office or the IDNR website. Excavations and collecting for commercial purposes are both prohibited, and a form for reporting what you found is available. Hours, fees, and access rules change. Verify with the operator or land agency before you go.
When is Mazonia-Braidwood State Fish & Wildlife Area (Mazon Creek Fossil Beds) open?
Fossil collecting is restricted to March 1 through September 30. The area is closed to fossil hunting October through February. Hours, fees, and access rules change. Verify with the operator or land agency before you go.
Is Mazonia-Braidwood State Fish & Wildlife Area (Mazon Creek Fossil Beds) good for kids?
Yes — Mazonia-Braidwood State Fish & Wildlife Area (Mazon Creek Fossil Beds) works for families. Kids can pick nodules off spoil piles easily and the hunting needs no tools — which suits the rules, since excavating is prohibited. The hazards are real: this is reclaimed strip mine with uneven ground and deep water-filled pits, so keep children close and stay off the pit edges.