Sioux County: Fossil Hunting in Sioux County, Nebraska

Updated June 2026

Sioux County is a mapped rockhounding spot in Sioux County, Nebraska. Reported finds include chalcedony, celestite, fossils, agatized wood, opalized wood. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Sioux County
State: Nebraska
Nearest road: Glen Road
Coordinates: 42.58867, -103.59525

Geology at Sioux County

This spot sits on Arikaree Group, mapped as sand and volcanic that formed roughly 28 to 5 million years ago. Fossils are uncommon in volcanic rock itself; look to any interbedded sediments and ash beds, where plant material and bone are typically preserved.

Mapped unit: Arikaree Group
Age: 28–5 Ma (Late Oligocene to Miocene)
Rock types: sand and volcanic
Elevation: 4,200 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 Sioux County

Best months: March to November. Typical highs run 88°F in midsummer and 39°F in midwinter, with winter lows near 11°F.

Climate normals: NOAA 1991-2020 monthlies, FT ROBINSON station (9 mi away), adjusted for elevation.

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 Sioux County

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 Sioux County.

Across the state line from Sioux County

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

Sioux County FAQ

Where is Sioux County?+

Sioux County is in Sioux County, Nebraska, at 42.58867, -103.59525. Nearest road: Glen Road.

What rocks and minerals can you find at Sioux County?+

Sioux County is reported to produce Chalcedony, Celestite, Fossils, Agatized Wood, Opalized Wood.

Is collecting allowed at Sioux County?+

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 Sioux County?+

A rock hammer, a cold chisel, safety glasses, and newspaper or foam for wrapping finds cover most fossil ground. A trowel and a sieve help in soft exposures.

When is the best time to visit Sioux County?+

The most comfortable months at Sioux County are March to November.

How do I get to Sioux County?+

Open the directions link to navigate to 42.58867, -103.59525 in Google Maps. The nearest road is Glen Road.

More rockhounding in Nebraska

See all 32 Nebraska spots →

Open Sioux County on the map

Use the RockHoundR app for live land overlays, weather, geology, directions, and saved finds.