Crowley Quarry: Flint Rockhounding in Mercer County, North Dakota

Updated June 2026

Crowley Quarry is a mapped rockhounding spot in Mercer County, North Dakota. Reported finds include flint. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Mercer County
State: North Dakota
Nearest road: County Road 26
Postcode: 58523
Coordinates: 47.33477, -101.80767

Geology at Crowley Quarry

This spot sits on Sentinel Butte Formation, mapped as siltstone, claystone, and sandstone that formed roughly 66 to 56 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: Sentinel Butte Formation
Age: 66–56 Ma (Paleocene)
Rock types: siltstone, claystone, and sandstone
Elevation: 1,970 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 Crowley Quarry

Best months: April to October. Typical highs run 85°F in midsummer and 23°F in midwinter, with winter lows near 2°F.

Climate normals: NOAA 1991-2020 monthlies, BEULAH 1 W 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.

Sources: RockHoundR public spot dataset, app land overlays, and local agency review before each trip.

Found at Crowley Quarry

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

Flint Encyclopedia →

Nearby rockhounding spots

Other rockhounding spots within driving distance of Crowley Quarry.

Crowley Quarry FAQ

Where is Crowley Quarry?+

Crowley Quarry is in Mercer County, North Dakota, at 47.33477, -101.80767. Nearest road: County Road 26.

What rocks and minerals can you find at Crowley Quarry?+

Crowley Quarry is reported to produce Flint.

Is collecting allowed at Crowley Quarry?+

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 Crowley Quarry?+

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 Crowley Quarry?+

The most comfortable months at Crowley Quarry are April to October.

How do I get to Crowley Quarry?+

Open the directions link to navigate to 47.33477, -101.80767 in Google Maps. The nearest road is County Road 26.

More rockhounding in North Dakota

See all 20 North Dakota spots →

Open Crowley Quarry on the map

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