Fallon: Montana Agate Rockhounding in Prairie County, Montana

Updated June 2026

Fallon is a mapped rockhounding spot in Prairie County, Montana. Reported finds include montana agate. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Prairie County
State: Montana
Nearest road: River Road
Postcode: 59326
Coordinates: 46.85299, -105.07822

Geology at Fallon

This spot sits on Alluvium, mapped as gravel, sand, and silt that formed within roughly the last 2 million years. Gravels like these concentrate whatever survives the river: agate, jasper, and other tough silica typically show up as rounded, waxy stones.

Mapped unit: Alluvium
Age: 2 Ma to present (Pleistocene to Holocene)
Rock types: gravel, sand, and silt
Elevation: 2,130 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 Fallon

Best months: March to November. Typical highs run 89°F in midsummer and 30°F in midwinter, with winter lows near 7°F.

Climate normals: NOAA 1991-2020 monthlies, MILDRED 7 NNW station (6 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 Fallon

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

Montana Agate Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Fallon.

Across the state line from Fallon

Fallon 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.

MedoraTop pick in North DakotaBillings County, North Dakota · 75 mi awayAgate, Chalcedony, Silicified Wood

Fallon FAQ

Where is Fallon?+

Fallon is in Prairie County, Montana, at 46.85299, -105.07822. Nearest road: River Road.

What rocks and minerals can you find at Fallon?+

Fallon is reported to produce Montana Agate.

Is collecting allowed at Fallon?+

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 Fallon?+

Most agate and jasper is surface float: bring a spray bottle, a pick or small shovel, and a sturdy bag. Wet stones show their banding and translucence.

When is the best time to visit Fallon?+

The most comfortable months at Fallon are March to November.

How do I get to Fallon?+

Open the directions link to navigate to 46.85299, -105.07822 in Google Maps. The nearest road is River Road.

More rockhounding in Montana

See all 87 Montana spots →

Open Fallon on the map

Use the RockHoundR app for live land overlays, weather, geology, directions, and saved finds.