Terry: Petrified Wood & Chalcedony Rockhounding in Prairie County, Montana

Updated June 2026

Terry is a mapped rockhounding spot in Prairie County, Montana. Reported finds include petrified wood, chalcedony, jasper. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Prairie County
State: Montana
Nearest road: Broadview Bench Road
Coordinates: 46.77271, -105.25989

Geology at Terry

This spot sits on Lebo Member of Fort Union Formation, mapped as shale, sandstone, and bentonite that formed roughly 66 to 62 million years ago. Sedimentary beds like these are the typical host for petrified and silicified wood, which weathers out as durable float on slopes and in washes.

Mapped unit: Lebo Member of Fort Union Formation
Age: 66–62 Ma (Paleocene)
Rock types: shale, sandstone, and bentonite
Elevation: 2,370 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 Terry

Best months: March to October. Typical highs run 88°F in midsummer and 28°F in midwinter, with winter lows near 6°F.

Climate normals: NOAA 1991-2020 monthlies, TERRY station (2 mi away).

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 Terry

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 Terry.

Terry FAQ

Where is Terry?+

Terry is in Prairie County, Montana, at 46.77271, -105.25989. Nearest road: Broadview Bench Road.

What rocks and minerals can you find at Terry?+

Terry is reported to produce Petrified Wood, Chalcedony, Jasper.

Is collecting allowed at Terry?+

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 Terry?+

A rock hammer, sturdy gloves, and a padded bag cover petrified wood hunting. Most pieces are surface float, so walking slopes and washes beats digging.

When is the best time to visit Terry?+

The most comfortable months at Terry are March to October.

How do I get to Terry?+

Open the directions link to navigate to 46.77271, -105.25989 in Google Maps. The nearest road is Broadview Bench Road.

More rockhounding in Montana

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