Fromberg: Coal & Pyrite Rockhounding in Carbon County, Montana

Updated June 2026

Fromberg is a mapped rockhounding spot in Carbon County, Montana. Reported finds include coal, pyrite. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Carbon County
State: Montana
Coordinates: 45.39299, -108.93163

Geology at Fromberg

This spot sits on Eagle Formation, mapped as sandstone and sandstone mudstone that formed roughly 86 to 72 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: Eagle Formation
Age: 86–72 Ma (Late Cretaceous)
Rock types: sandstone and sandstone mudstone
Elevation: 3,740 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 Fromberg

Best months: March to November. Typical highs run 87°F in midsummer and 35°F in midwinter, with winter lows near 12°F.

Climate normals: NOAA 1991-2020 monthlies, BRIDGER 2 N station (5 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 Fromberg

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 Fromberg.

Across the state line from Fromberg

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

Fromberg FAQ

Where is Fromberg?+

Fromberg is in Carbon County, Montana, at 45.39299, -108.93163.

What rocks and minerals can you find at Fromberg?+

Fromberg is reported to produce Coal, Pyrite.

Is collecting allowed at Fromberg?+

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 Fromberg?+

A rock hammer, gloves, and safety glasses cover old mining-district ground. Stay out of shafts and adits; the best specimens typically come from dump piles.

When is the best time to visit Fromberg?+

The most comfortable months at Fromberg are March to November.

How do I get to Fromberg?+

Open the directions link to navigate to 45.39299, -108.93163 in Google Maps. Some spots are remote, so check road conditions before driving out.

More rockhounding in Montana

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Open Fromberg on the map

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