Fort Washakie: Moss Agate & Chalcedony Rockhounding in Fremont County, Wyoming

Plan your visit

Permission required before collecting

County

Fremont County

State

Wyoming

Coordinates

43.13182, -108.97879

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 Fort Washakie

Comfortable months (45 to 90°F highs)

Best months: March to October. Typical highs run 84°F in midsummer and 35°F in midwinter, with winter lows near 7°F.

Climate normals: NOAA 1991-2020 monthlies, DIVERSION DAM station (7 mi away), adjusted for elevation.

Geology at Fort Washakie

This spot sits on Alluvium and Colluvium, mapped as clay, silt, and sand that formed within roughly the last 3 million years. Gravels like these concentrate whatever survives the river: agate, jasper, and other tough silica typically show up as rounded, waxy stones.

Mapped unit

Alluvium and Colluvium

Age

3 Ma to present (Pleistocene to Holocene)

Rock types

clay, silt, and sand

Elevation

5,860 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.

State guidance last verified: April 1, 2026

• BLM Wyoming
• Wyoming State Geological Survey
• Fossil Butte National Monument
• Community submissions reviewed against published agency rules