Horseshoe Hills: Fossil Hunting in Gallatin County, Montana

Updated June 2026

Horseshoe Hills is a mapped rockhounding spot in Gallatin County, Montana. Reported finds include shale, trilobite fossils. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Gallatin County
State: Montana
Coordinates: 46.02226, -111.27120

Geology at Horseshoe Hills

This spot sits on Three Forks through Maywood Formation: Three Forks, Jefferson, and Maywood Formations or Palliser and Alexo Formations, and Fairholme Group in northwestern Montana near Canadian border, mapped as limestone, dolostone, and shale that formed roughly 370 to 345 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: Three Forks through Maywood Formation: Three Forks, Jefferson, and Maywood Formations or Palliser and Alexo Formations, and Fairholme Group in northwestern Montana near Canadian border
Age: 370–345 Ma (Late Devonian to Mississippian)
Rock types: limestone, dolostone, and shale
Elevation: 6,520 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 Horseshoe Hills

Best months: April to October. Typical highs run 76°F in midsummer and 25°F in midwinter, with winter lows near 7°F.

Climate normals: NOAA 1991-2020 monthlies, TRIDENT station (11 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 Montana — Recreational mineral collecting
Montana Bureau of Mines and Geology
Gem Mountain Sapphire Mine (fee-dig operator)
Community submissions reviewed against published agency rules

Found at Horseshoe Hills

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 Horseshoe Hills.

Horseshoe Hills FAQ

Where is Horseshoe Hills?+

Horseshoe Hills is in Gallatin County, Montana, at 46.02226, -111.27120.

What rocks and minerals can you find at Horseshoe Hills?+

Horseshoe Hills is reported to produce Shale, Trilobite Fossils.

Is collecting allowed at Horseshoe Hills?+

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 Horseshoe Hills?+

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 Horseshoe Hills?+

The most comfortable months at Horseshoe Hills are April to October.

How do I get to Horseshoe Hills?+

Open the directions link to navigate to 46.02226, -111.27120 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Montana

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Open Horseshoe Hills on the map

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