Thermopolis: Selenite & Travertine Rockhounding in Hot Springs County, Wyoming

Updated June 2026

Thermopolis is a mapped rockhounding spot in Hot Springs County, Wyoming. Reported finds include selenite, travertine. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Hot Springs County
State: Wyoming
Coordinates: 43.68828, -108.21301

Geology at Thermopolis

This spot sits on Cloverly, Morrison, Sundance, and Gypsum Spring Formations, mapped as sandstone, claystone, and shale that formed roughly 175 to 100 million years ago. Sedimentary rock like this erodes unevenly, so the most productive collecting is typically along fresh cuts, badland slopes, and active drainages.

Mapped unit: Cloverly, Morrison, Sundance, and Gypsum Spring Formations
Age: 175–100 Ma (Middle Jurassic to Early Cretaceous)
Rock types: sandstone, claystone, and shale
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.

Best time to visit Thermopolis

Best months: March to June. Typical highs run 91°F in midsummer and 37°F in midwinter, with winter lows near 11°F.

Climate normals: NOAA 1991-2020 monthlies, THERMOPOLIS station (3 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.

State guidance last verified: April 1, 2026

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

Found at Thermopolis

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 Thermopolis.

Thermopolis FAQ

Where is Thermopolis?+

Thermopolis is in Hot Springs County, Wyoming, at 43.68828, -108.21301.

What rocks and minerals can you find at Thermopolis?+

Thermopolis is reported to produce Selenite, Travertine.

Is collecting allowed at Thermopolis?+

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 Thermopolis?+

A rock hammer, sturdy gloves, safety glasses, and a collecting bag cover the basics here. Add a spray bottle: wet rock shows color and pattern that dry rock hides.

When is the best time to visit Thermopolis?+

The most comfortable months at Thermopolis are March to June.

How do I get to Thermopolis?+

Open the directions link to navigate to 43.68828, -108.21301 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Wyoming

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Open Thermopolis on the map

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