Agate Fossil Beds: Agate & Jasper Rockhounding in Sioux County, Nebraska

Plan your visit

Generally open to casual rockhounding

County

Sioux County

State

Nebraska

Nearest road

River Road

Coordinates

42.43663, -103.73587

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.

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 Agate Fossil Beds

Comfortable months (45 to 90°F highs)

Best months: March to November. Typical highs run 86°F in midsummer and 38°F in midwinter, with winter lows near 9°F.

Climate normals: NOAA 1991-2020 monthlies, HARRISON 20 SSE station (1 mi away).

Geology at Agate Fossil Beds

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

4,480 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.

• Nebraska National Forests and Grasslands
• Conservation and Survey Division, University of Nebraska
• Nebraska Game and Parks rules
• Community submissions reviewed against published agency rules