Thebes: Agate & Jasper Rockhounding in Alexander County, Illinois

Updated June 2026

Thebes is a mapped rockhounding spot in Alexander County, Illinois. Reported finds include agate, jasper. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Alexander County
State: Illinois
Nearest road: Old Route 3
Postcode: 62990
Coordinates: 37.23933, -89.44224

Geology at Thebes

This spot sits on ground mapped as dolostone and limestone that formed roughly 445 to 420 million years ago. Chert and agate nodules typically form inside carbonate rock like this and weather out as tough, waxy lumps in soils and creek beds.

Age: 445–420 Ma (Llandovery to Pridoli)
Rock types: dolostone and limestone
Elevation: 330 ft

Geologic mapping via Macrostrat and the underlying state geological survey maps (CC BY 4.0). Bedrock at the surface can vary within a mapped unit.

Best time to visit Thebes

Best months: February to December. Typical highs run 89°F in midsummer and 43°F in midwinter, with winter lows near 26°F.

Climate normals: NOAA 1991-2020 monthlies, CAPE GIRARDEAU MUNI AP station (8 mi away).

Land & collecting status

Generally open to casual rockhounding

Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig.

Public-land rules vary by agency, season, and field office. The RockHoundR app pulls live BLM, USFS, NPS, and tribal overlays so you can see exactly which agency manages the ground at this spot.

Sources & verification

Spot details combine the public RockHoundR location dataset, normalized mineral labels, agency land-status checks in the app, and community submissions. Coordinates are approximate until verified in the field.

Sources: RockHoundR public spot dataset, app land overlays, and local agency review before each trip.

Found at Thebes

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

Nearby rockhounding spots

Other rockhounding spots within driving distance of Thebes.

Across the state line from Thebes

Thebes is close enough to the Illinois border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

Thebes FAQ

Where is Thebes?+

Thebes is in Alexander County, Illinois, at 37.23933, -89.44224. Nearest road: Old Route 3.

What rocks and minerals can you find at Thebes?+

Thebes is reported to produce Agate, Jasper.

Is collecting allowed at Thebes?+

Generally open to casual rockhounding. Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Thebes?+

Most agate and jasper is surface float: bring a spray bottle, a pick or small shovel, and a sturdy bag. Wet stones show their banding and translucence.

When is the best time to visit Thebes?+

The most comfortable months at Thebes are February to December.

How do I get to Thebes?+

Open the directions link to navigate to 37.23933, -89.44224 in Google Maps. The nearest road is Old Route 3.

More rockhounding in Illinois

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Open Thebes on the map

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