Spillman Creek: Geode Digging in Hancock County, Illinois

Updated June 2026

Spillman Creek is a mapped rockhounding spot in Hancock County, Illinois. Reported finds include geode, pyrite, chalcedony, sphalerite, quartz. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Hancock County
State: Illinois
Nearest road: North County Road 1540
Postcode: 62358
Coordinates: 40.61633, -91.20302

Geology at Spillman Creek

This spot sits on St. Louis Limestone, mapped as limestone that formed roughly 345 to 330 million years ago. Limestone country like this is classic geode ground: cavities in the carbonate rock can line themselves with quartz or calcite crystals.

Mapped unit: St. Louis Limestone
Age: 345–330 Ma (Mississippian)
Rock types: limestone
Elevation: 590 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 Spillman Creek

Best months: March to November. Typical highs run 85°F in midsummer and 33°F in midwinter, with winter lows near 17°F.

Climate normals: NOAA 1991-2020 monthlies, FT MADISON station (7 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 Spillman Creek

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 Spillman Creek.

Across the state line from Spillman Creek

Spillman Creek 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.

Spillman Creek FAQ

Where is Spillman Creek?+

Spillman Creek is in Hancock County, Illinois, at 40.61633, -91.20302. Nearest road: North County Road 1540.

What rocks and minerals can you find at Spillman Creek?+

Spillman Creek is reported to produce Geode, Pyrite, Chalcedony, Sphalerite, Quartz.

Is collecting allowed at Spillman Creek?+

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 Spillman Creek?+

Bring a crack hammer, a chisel, safety glasses, and a bucket. Candidates are rounder and lighter than solid rock; a soil pipe cutter opens them cleaner than a flat smash.

When is the best time to visit Spillman Creek?+

The most comfortable months at Spillman Creek are March to November.

How do I get to Spillman Creek?+

Open the directions link to navigate to 40.61633, -91.20302 in Google Maps. The nearest road is North County Road 1540.

More rockhounding in Illinois

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Open Spillman Creek on the map

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