Hyattville: Fossil Hunting in Big Horn County, Wyoming

Updated June 2026

Hyattville is a mapped rockhounding spot in Big Horn County, Wyoming. Reported finds include gypsum, dinosaur bones, gastroliths, fossils. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Big Horn County
State: Wyoming
Nearest road: Rea Grove Lane
Coordinates: 44.24413, -107.52598

Geology at Hyattville

This spot sits on Sundance and Gypsum Spring Formations, mapped as sandstone, shale, and dolostone that formed roughly 175 to 145 million years ago. Limestone like this typically forms in ancient seas, so marine fossils such as brachiopods, corals, and crinoids tend to weather out of fresh exposures.

Mapped unit: Sundance and Gypsum Spring Formations
Age: 175–145 Ma (Middle Jurassic to Late Jurassic)
Rock types: sandstone, shale, and dolostone
Elevation: 5,050 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 Hyattville

Best months: March to November. Typical highs run 87°F in midsummer and 36°F in midwinter, with winter lows near 14°F.

Climate normals: NOAA 1991-2020 monthlies, TENSLEEP 4NE station (14 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 Hyattville

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 Hyattville.

Across the state line from Hyattville

Hyattville is close enough to the Wyoming border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

Hyattville FAQ

Where is Hyattville?+

Hyattville is in Big Horn County, Wyoming, at 44.24413, -107.52598. Nearest road: Rea Grove Lane.

What rocks and minerals can you find at Hyattville?+

Hyattville is reported to produce Gypsum, Dinosaur Bones, Gastroliths, Fossils.

Is collecting allowed at Hyattville?+

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 Hyattville?+

A rock hammer, a cold chisel, safety glasses, and newspaper or foam for wrapping finds cover most fossil ground. A trowel and a sieve help in soft exposures.

When is the best time to visit Hyattville?+

The most comfortable months at Hyattville are March to November.

How do I get to Hyattville?+

Open the directions link to navigate to 44.24413, -107.52598 in Google Maps. The nearest road is Rea Grove Lane.

More rockhounding in Wyoming

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Open Hyattville on the map

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