Boulder Mountains: Pyrolusite Rockhounding in Garfield County, Utah

Updated June 2026

Boulder Mountains is a mapped rockhounding spot in Garfield County, Utah. Reported finds include pyrolusite. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Garfield County
State: Utah
Nearest road: Tantalus Flat Road
Coordinates: 38.09970, -111.33069

Geology at Boulder Mountains

This spot sits on Alluvium and colluvium, mapped as unconsolidated alluvium and colluvium that formed within roughly the last 3 million years. Loose deposits like these are float-collecting ground: erosion keeps moving durable rocks and minerals into gravel bars, cutbanks, and washes.

Mapped unit: Alluvium and colluvium
Age: 3 Ma to present (Quaternary)
Rock types: unconsolidated alluvium and colluvium
Elevation: 8,540 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 Boulder Mountains

Best months: March to October. Typical highs run 80°F in midsummer and 30°F in midwinter, with winter lows near 10°F. At about 8,540 ft, snow can block access from late fall well into spring, so check conditions outside of summer.

Climate normals: NOAA 1991-2020 monthlies, CAPITOL REEF NP 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 Utah — Rockhounding overview
Utah Geological Survey — collecting guidelines
SITLA — surface use rules
Community submissions reviewed against published agency rules

Found at Boulder Mountains

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

Pyrolusite Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Boulder Mountains.

Boulder Mountains FAQ

Where is Boulder Mountains?+

Boulder Mountains is in Garfield County, Utah, at 38.09970, -111.33069. Nearest road: Tantalus Flat Road.

What rocks and minerals can you find at Boulder Mountains?+

Boulder Mountains is reported to produce Pyrolusite.

Is collecting allowed at Boulder Mountains?+

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 Boulder Mountains?+

A rock hammer, sturdy gloves, safety glasses, and a collecting bag cover the basics here. Add a spray bottle: wet rock shows color and pattern that dry rock hides.

When is the best time to visit Boulder Mountains?+

The most comfortable months at Boulder Mountains are March to October. At about 8,540 ft, snow can block access from late fall well into spring, so check conditions outside of summer.

How do I get to Boulder Mountains?+

Open the directions link to navigate to 38.09970, -111.33069 in Google Maps. The nearest road is Tantalus Flat Road.

More rockhounding in Utah

See all 246 Utah spots →

Open Boulder Mountains on the map

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