Cave-In Rock: Barite & Calcite Rockhounding in Hardin County, Illinois

Plan your visit

Generally open to casual rockhounding

County

Hardin County

State

Illinois

Nearest road

Hastie Mine Road

Postcode

62919

Coordinates

37.50321, -88.20518

Coordinates are approximate. Confirm the exact ground in the RockHoundR app, where land overlays show which agency manages the area.

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.

Access note: Collecting is prohibited inside Cave-In-Rock State Park itself. The productive mine dumps sit on private inholdings and require written landowner permission, while parts of the surrounding Shawnee National Forest allow non-disturbing surface collection of hand-sized rocks and minerals for personal use. Ohio River gravel and public road cuts near town can yield weathered fluorite float. Verify land ownership before collecting. Hardin County.

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.

Best time to visit Cave-In Rock

Comfortable months (45 to 90°F highs)

Best months: February to December. Typical highs run 86°F in midsummer and 41°F in midwinter, with winter lows near 22°F.

Climate normals: NOAA 1991-2020 monthlies, ELIZABETHTOWN station (7 mi away).

Geology at Cave-In Rock

This spot sits on Ste. Genevieve Limestone, mapped as limestone that formed roughly 345 to 330 million years ago. Carbonate rock like this dissolves and weathers readily, so fresh road cuts, quarries, and creek exposures are typically the most productive ground.

Mapped unit

Ste. Genevieve Limestone

Age

345–330 Ma (Mississippian)

Rock types

limestone

Elevation

460 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.

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.

• Illinois State Geological Survey
• Illinois DNR site rules
• Shawnee National Forest
• Community submissions reviewed against published agency rules