Fremont County: Agate & Chalcedony Rockhounding in Fremont County, Wyoming

Plan your visit

Generally open to casual rockhounding

County

Fremont County

State

Wyoming

Nearest road

Continental Divide National Scenic Trail

Coordinates

42.53775, -108.94056

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 Fremont County

Comfortable months (45 to 90°F highs)

Best months: April to October. Typical highs run 75°F in midsummer and 26°F in midwinter, with winter lows near 0°F. At about 8,530 ft, snow can block access from late fall well into spring, so check conditions outside of summer.

Climate normals: NOAA 1991-2020 monthlies, SOUTH PASS CITY station (9 mi away), adjusted for elevation.

Geology at Fremont County

This spot sits on ground mapped as Quartz diorite of the Louis Lake Batholith that formed roughly 4030 to 2500 million years ago. Plutonic rock like this weathers slowly into grus and boulders, and the most productive collecting is typically in weathered zones and drainages.

Mapped unit

Quartz diorite of the Louis Lake Batholith

Age

4030–2500 Ma (Archean)

Elevation

8,530 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