Oglala: Agate & Chalcedony Rockhounding in Oglala Lakota County, South Dakota

Plan your visit

Permission required before collecting

County

Oglala Lakota County

State

South Dakota

Coordinates

43.29633, -102.91047

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

Land & collecting status

Permission required before collecting

Requires landowner or agency permission before any collecting. Do not enter without explicit authorization.

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 Oglala

Comfortable months (45 to 90°F highs)

Best months: March to November. Typical highs run 88°F in midsummer and 37°F in midwinter, with winter lows near 14°F.

Climate normals: NOAA 1991-2020 monthlies, OGLALA 1S station (12 mi away).

Geology at Oglala

This spot sits on White River Group, mapped as claystone, siltstone, and sandstone that formed roughly 56 to 23 million years ago. Tough silica like agate, jasper, and chert typically weathers out of beds like these and collects as float in drainages and on deflation surfaces.

Mapped unit

White River Group

Age

56–23 Ma (Eocene to Oligocene)

Rock types

claystone, siltstone, and sandstone

Elevation

3,070 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.

• BLM Montana-Dakotas rockhounding rules
• Buffalo Gap National Grassland
• South Dakota Geological Survey
• Community submissions reviewed against published agency rules